i

Addis Ababa University

Addis Ababa Institute of Technology (AAiT)

School of Chemical and Bio Engineering

Byproducts Utilization from Wheat Milling Industries for

Development of Value Added Products

A Thesis Submitted to the School of Chemical and Bio Engineering of Addis

Ababa Institute of Technology, in Partial Fulfillment of the requirements for the

Degree of Master of Science in Chemical Engineering (Food Engineering Stream)

By: Yemsrach Yishak

Advisor: Dr. Eng. Shimelis Admassu (Associate Professor)

Addis Ababa, Ethiopia

March, 2014

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Addis Ababa University

Addis Ababa Institute of Technology (AAiT)

School Of Chemical and Bio-Engineering

Food Engineering Stream

Byproducts Utilization from Wheat Milling Industries for Development of

Value Added Products

A Thesis Submitted to the School of Graduate Studies of Addis Ababa Institute

of Technology, in Partial Fulfillment of the Requirements for the Degree of

Master of Science in Chemical Engineering (Food Engineering Stream)

By: Yemsrach Yishak

Approved by the Examining Board Signatures

Ato Taye Zewdu (Chair man, Department’s Graduate Committee)

Dr. Eng. Shimelis Admassu (Associate professor)

(Advisor)

Ato Adamu Zegeye

(Internal Examiner)

Dr. Ashagrie Zewdu

(External Examiner)

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Acknowledgments

First and for most of all I would love to thank Almighty God for all the blessings he has

given me; enabling me to accomplish this thesis work, for all the special people surrounded

me. Apart from my effort the success of this thesis depends mainly on the encouragement,

guidelines, assistance and support of many others. I take this opportunity to express my

gratitude, for the people who have been instrument in the successful achievement of this

thesis.

First, I would love to express my deepest appreciation to my thesis advisor Dr. Eng. Shimelis

Admassu starting from choosing the right topic and guided me through. Your advice, hard

work, inspirational conversations, the ability to look, wonder and dare to see beyond the

limits makes you exceptional. Thanks for all the encouragement, guidance and assistance;

and of course love to express my sincere gratitude to Mr. Bekele Mekuria, for assisting me

and fill me with new ideas and clues during my preliminary work.

I genuinely acknowledge Prof. Kibret Mequanint; your efforts were backbones to the whole

thesis work. Thank you for the financial support, willingness, and all the positive feedbacks.

I love to acknowledge Ato Hintsa for continuously trying to work with devotion, without

your effort and miracle job on Supper critical fluid extractor machine my thesis work would

have been totally different.

Most importantly of all, I express my deep sense of gratitude to my most affectionate and

beloved fiancé and family for all the spectra you ran for me. Thanks for being there for me

for each never last seem journey. You taught me to never surrender for battles in my life, and

keep on reminding me that God is already there. I just want to say thank you for your love,

undying encouragement, wisdom, advice, and for being there in every aspect of my life. Meri

my little sister extra thanks to you dear, you really mean something to me. I honestly could

not have done this without your support.

And last but not least, my friends Habtish and Dera I’m grateful from the bottom of my

hypothalamus, thanks for assisting me when I was in need of support; Dr. Ashagre, PHD

students Alexa and Engida in Science Faculty without your guidance all would have been

impossible. Finally, I would love to thank Sirgute and Tigist for all the secretarial works you

help me out.

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Abstract

The main byproducts of wheat milling industries, wheat germ and bran, have been known as

an outstanding sources of protein, dietary fiber, trace minerals, antioxidants, phytochemicals

and allied micronutrients. This research was conducted to evaluate utilization of wheat germ

(WG) and wheat bran (WB) for the development of value added cookies and tea substitute

products; respectively. Supercritical fluid extractor (SFE) was used to extract oil from wheat

germ and the defatted wheat germ flour (DWGF) was used as a supplement for wheat flour at

10%, 15% and 20% blending ratios (BR1, BR2 &BR3) and baking temperatures of 150, 180

and 210 oC (T1, T2 &T3).Wheat bran (WB), the other byproduct of wheat milling industries,

used to made tea substitute by milling, screening, and heating before utilized as final product.

Chemical composition of raw materials, physico-chemical and rheological characteristics of

flours were investigated prior to cookies preparation. Proximate analysis for wheat flour

(WF)(0.83,11.92,0.52,0.45,9.33) and defatted wheat germ flour (DWGF) (4.72,

12.98,1.01,5.17,28.11); for ash, moisture, fat, fiber and protein were resulted respectively; as

a result nutrient dense DWGF used as a substitute for development of cookies . It was found

that protein, fiber, ash and minerals (Ca, K, P, and Mg) contents in the blends increased

significantly (P<0.05) with an increase in DWGF substitution. The effect of BR2 and T2 on

proximate composition resulted with (protein (14.29), fiber (2.84), and ash (1.31)) resulted

better together with sensory quality evaluation. Rheological and functional properties of

flours, physical properties for cookies and organoleptic properties for both products were

analyzed. Total phenolic content (TPC) and antioxidant activity were determined by using

Folin-Ciocalteu and DPPH scavenging activity assays respectively. Extraction procedure

went out using methanol at three different temperatures (40, 60 and 80)0C. Higher total

phenolic content ranged from 1.037 to 3.68mg of gallic acid equivalent (GAE)/gm of dried

extract obtained at 60 0C using methanol. While antioxidant activity with lower half maximal

inhibitory concentration (IC50) (mg/ml) value of (1.4, 1.75, 2.13) scavenging activity for

ascorbic acid, methanol solvent extract of wheat bran and by absolute methanol respectively.

Finally, cookies baked at 180oC using blend ratio 15 % resulted better sensory qualification

and wheat bran extracted using solvent methanol at 60oC showed potential antioxidant

activity and TPC.

Keywords: defatted wheat germ, cookies, antioxidant, folin-Ciocalteu assay, DPPH

scavenging capacity assay

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Table of contents

Chapter Title Page

Title page

Acknowledgements

Abstract

Table of contents

List of tables

List of figures

List of abbreviations

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ii

iii

iv

v

viii

ix

1 Introduction

1

1.1 Background 1

1.2 Statement of the problem 3

1.3 Objectives 4

1.4 Limitation of the study 4

1.5 Significance of the study 5

2 Literature Review

6

2.1 Overview on cereals 6

2.1.1 Wheat consumption and production in Ethiopia 7

2.1.2 Uses and varities of wheat 8

2.1.3 Morphology and composition of wheat 11

2.2 Effect of milling process 12

2.3 Phytochemicals and antioxidants 14

2.4 Raw materials for developed products 17

2.4.1 Wheat bran 17

2.4.2 Wheat germ 19

2.5 Process description 21

2.5.1 Process description for wheat flow 21

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2.5.2 Process description for biscuit production 25

2.6 Sensory quality attributes 31

2.7 Concluding Remarks 32

3 Materials and Methods 34

3.1 Raw material collection, transportation, preparation and storage 34

3.2 Frame work of the research experiment 35

3.3 Methods of processing 36

3.3.1 Preparation of defatted wheat germ flour 36

3.3.2 Blend formulation and cookies production 37

3.4 Methods of analysis 39

3.4.1 Analysis of proximate composition of flours and cookies 39

3.4.2Determination of rheology property of flours 44

3.4.3 Determination of functional properties of flours 44

3.4.4 Determination of physical properties of cookies 44

3.5 Analysis of antioxidant activity and total phenolics 45

3.5.1 Sample extraction 45

3.5.2 Determination of total phenolic content 45

3.5.3 Determination of free radical scavenging activity 46

3.6 Sensory quality evaluation 48

3.7 Experimental design and statistical data analysis 48

4 Result and Discussion 49

4.1 Proximate chemical composition of flours and cookies 49

4.2 Effect of Blend ratio and baking temperature on

Proximate composition of cookies 50

4.2.1 Effect of blend ratio and baking temperature on

moisture content 50

4.2.2 Effect of blend ratio and baking temperature on crude

protein 51

4.2.3 Effect of blend ratio and baking temperature on

crude fiber 52

4.2.4 Effect of blend ratio and baking temperature on ash 52

4.3 Rheological property of flours 53

4.3.1 Water absorption 53

4.3.2 Dough development time 55

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4.3.3 Dough stability 56

4.3.4 Farinograph quality number (FQN) 56

4.4 Functional properties of flours 56

4.4.1 Bulk density 56

4.4.2 Water absorption capacity 57

4.4.3 Oil absorption capacity 57

4.5 Physical properties of cookies 58

4.5.1 Effect of blend ratio and baking temperature on weight of cookies 58

4.5.2 Effect of blend ratio and baking temperature on diameter of cookies 59

4.5.3 Effect of blend ratio and baking temperature on cookies height 59

4.5.4 Effect of blend proportion and temperature on spread ratio 59

4.6 Total phenolic content and antioxidant activity of bran 60

4.6.1 Total phenolic content of wheat bran 60

4.6.2 Antioxidant content of wheat bran 61

4.7 Sensory quality evaluation of products 62

5 Process Technology 64

5.1 Production process for cookies and tea substitute 64

5.2 Suggested cookies manufacturing plant 65

6 Conclusion and Recommendation 67

6.1 Conclusion 67

6.2 Recommendation 68

References 69

Appendices 76

Appendix I Score card for the sensory quality evaluation using nine point hedonic scales

for cookies

76

Appendix II Score card for the sensory quality evaluation using nine point hedonic

scales for tea substitute

77

Appendix III Data obtained for bran extraction and tests 78

Appendix IV Pictorial representations for actual frame work 80

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List of tables

Table Title Page

2.1 Wheat composition and the milling process effect on nutrient composition 12

2.2 Fatty acid composition of wheat germ oil 19

3.1 percentage composition of composite flour for cookies 36

4.1 Proximate composition and mineral of flours 47

4.2 Effect of blend ratio & baking temperature on proximate composition 51

4.3 Mineral composition of biscuit at different blend proportion 53

4.4 Functional properties of flours 58

4.5 Physical Properties of cookies 58

4.6 Effect of blend ratio and temperature on diameter of cookie 59

4.12 Effect of blend ratio and temperature on cookie height 59

4.13 Effect of blend proportion and temperature on spread ratio 60

5.1 Legend for suggested cookies manufacturing plant 66

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List of figures

Figure Title Page

2.1 Production of key crops from 2010-2013 5

2.2 Schematic diagram of wheat 11

2.3 Free radicals and disease 16

2.4 Process steps in wheat milling 23

2.4 Schematic representation of idealized phase diagram 25

2.5 Parameters in Pharinograph representation 28

2.6 Wheat production trend in Ethiopia 31

3.1 Wheat grain and its byproducts (from Hora Complex PLC.) 33

3.2 Frame work of the research experiment 34

3.3 Oil obtained from defatted wheat germ flour (DWGF) using supercritical fluid

extractor (SFE) before and after separation via separatory funnel 35

3.4 Simplified diagram for Preparation of DWGF 36

3.5 Blended flours, defatted wheat germ flour and control flour 37

3.6 Extraction method for antioxidant activities and phenolics analysis 45

4.1 Farinograph values of control flour/ WF 54

4.2 Farinograph value for BR1 54

4.3 Farinograph measurement for BR2 55

4.4 Farinograph value for BR3 55

4.6 Free radical scavenging methanolic extract of wheat bran and control 62

4.7 Sensory quality evaluation for products 62

5.1 Flow chart diagram for deloped products 64

5.2 Equipment layouts for cookies production 65

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List of Abbreviations

AACC American Association of Cereal Chemists

AOAC Association of Analytical Chemist

BR1 Blend ratio 10% substitute of wheat flour

BR2 Blend ratio 15% substitute of wheat flour

BR3 Blend ratio 20% substitute of wheat flour

DPPH 2,2-diphenyl,1-picrylhydrazyl

DWGF defatted wheat germ flour

EGTE Ethiopia Grain Trade Enterprise

EHNRI Ethiopian Health and Nutrition Research Institute

Eq. Equation

FAO Food and Agricultural Organization

FQN Farinograph quality number

FU Farinograph Unit

IC 50 Half maximal inhibitory concentration

IFIC International food information council foundation

Mmt million metric tones

OAC Oil absorption capacity

ODC Ozone depleting chemicals

SD Standard deviation

TPC total phenolic content

t/ha Ton per hectare

VOC Volatile organic compounds

WAC Water absorption capacities

WF Wheat flour

WHO World Health Organization

1

CHAPTER ONE

Introduction

1.1 Background

Cereal crops are staple foods that provide essential nutrients to numerous populations of the

world. Cereals are dominant in the food sector because they are a versatile and reliable source

of food. They are easy to store and may be used to produce a myriad of food products.

Cereals processing thus forms a large and important part o f the food production chain. It also

plays a lesser, but no less important role in the non-food sector. It is for these reasons that

ways of improving cereal processing technology and practice need to be addressed on a

continual basis. Practically every meal produced today contains cereals in some form, while

the range of non-food applications (Galvin, 2001).

Wheat is a farinaceous grass, known botanically as triticum spp., is one of the most consumed

cereal grains worldwide and makes up a substantial part of the human diet. It provides more

nourishment (calories & proteins) for humans than any other single food crops. According to

Statista 2013/2014, the global production volume of wheat amounted approximately 710

million metric tons, which has shown a 7.7% increment from the previous year. It is the

second most important food crop in the developing world after rice. In sub-Saharan Africa,

14 countries produce wheat; Ethiopia and South Africa are the two major producers. Along

with Teff, wheat and maize represent the three most important cereal crops in Ethiopia.

Wheat is one of the various cereal crops largely grown in highlands of Ethiopia. It is

produced largely in the southeast, central and northwest parts of Ethiopia (Karin & Leo,

2013).

Cereal processing industry may be described as any industry that takes a cereal or a cereal

product as its raw material. The wheat-based industry is a multi-billion dollar market; hence

wheat is one of the top three cereals crop in the world. The milling process of wheat produces

large amount of wheat bran and germ as a byproduct. During milling, the endosperm is

broken down into fine particles (white flour) while bran and germ are removed. Wheat is a

significant agricultural and dietary commodity worldwide with known antioxidant properties

concentrated mostly in the bran. Wheat germ, being a byproduct of the flour milling industry,

is reported to be one of the most potential and excellent sources of much-needed vitamins,

minerals, dietary fiber, calories, proteins, and some functional micro-compositions at a

relative low cost (Yiqiang et al., 2001 and Shao & LiYu, 2011).

2

In general from wheat milling industries release a byproduct of (25-40) % and these by-

products utilized for animal feed, bioethanol production, succinic acid production, like a

blend for baked products as nutritional improvement, for cosmetics, meat substitute,

neutraceutical/ pharmaceutical products and for many more others. A value addition, any step

in the production process that improves the product for the customer and results in a higher

net worth of the last product. Using by-products from wheat milling industries for value

addition is accustomed in the developed countries like U.S.A for instance defatted wheat

germ helps meet today’s demands for full flavor grain-based foods that are rich in protein and

fiber (Dotty, 2012).

Oil inside the wheat germ extracted using different mechanisms such as the common method

organic solvent extraction (Hexane, Methanol, Chloroform-methanol, etc) which recovers

about 90% of the oil, by mechanical pressing, which recovers about 50% (Singh and Rice

1979) or by using super critical extraction methods (85%). The extracted wheat germ oil from

the former two mechanisms resulted in having lower free fatty acid and α-tocopherol content;

in other word oil obtained by supper critical extraction can overcome these negative factors;

in fact, the oils are solvent-free and do not need the traditional refining processes, and

extraction yields are similar to those usually need to be refined (Panfali et. al, 2003).

Above all, recent research demonstrates that wheat grain contains significant level of natural

antioxidants, mostly concentrated at the outer part. Wheat is an important agricultural

commodity and a primary food ingredient worldwide and contains considerable beneficial

nutritional components. Wheat and wheat-based food ingredients rich in natural antioxidants

can ideally serve as the basis for development of functional foods designed to improve the

health of millions of consumers (Tomas et. al., 2014).

Tea/ coffee substitutes are non-coffee products, usually without caffeine, that are used to

imitate coffee. This substitutes can be used for younger children, medical, economic and

religious reason, or simply because coffee is not readily available. Coffee and tea substitutes

made from wheat and barley have been produced for a century; however, limited research has

gone into the antioxidant benefits from roasted wheat and coffee beverages. As the benefits

of wheat antioxidants become better known, the wheat and coffee beverage markets may

emerge as well. According to researches by naturopathic clinic caffeine stimulates central and

sympathetic nervous systems, resulting in an elevation of the stress hormones released by

pituitary, adrenal and hypothalamus glands. These hormones can cause short term spikes in

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our blood pressure by raising both systolic and diastolic pressures. Release of stress

hormones causes our body to enter a state similar to a fight or flight response, causing blood

to be redirected from our stomach and digestive system and potentially causing indigestion

(Doty, 2012).

1.2. Statement of the problem

Wheat milling industries process and finally ground wheat kernel in to flour by separating the

wheat grain in to its constituents endosperm, bran and germ. The end product flour mainly

contains endosperm where as bran and germ removed as byproduct from wheat milling

industries. Wheat bran removed from being part of final flour with aim to produce flour with

a white rather than a brown color, and eliminated the fiber. Neither of these objectives is

necessarily desirable from the nutritional point of view. Similarly, for the reason that wheat

germ, if left in flour, has an adverse effect on the functional properties of dough, and reduces

the shelf life of final flour hence it’s rich in polyunsaturated fats (which have a tendency to

oxidize and become rancid on storage). Consequently wheat germ removed during processing

improved the storage qualities of flour and milled as part of mill feed and the final flour/

white flour sold without enrichment process.

Abroad, countries like United States, Far East and others developed countries managed to

utilize their wheat milling industries byproducts beyond meeting the nutritional needs of their

customers. Wheat germ used as a resource for value addition purpose after extracting the oil.

When wheat germ defatted; it becomes ideal ingredient for grain based products; hence it is

high in protein, fiber and is virtually fat free. Processing and finally blending with wheat

flour to get better functional qualities included improved stability, nutritional values and

flavor of processed foods besides making consumer goods of all kinds.

The basic problems in developing countries like ours unlike the developed ones; instead of

maximizing (using available) resources in our hand, lose it as if we couldn’t gain any

importance from it. Hence , the number of wheat milling industries are increasing year after

year, as that of consumption and production of wheat; then utilizing the (25- 40) % of the

total would be nice than waste it.

Wheat milling industries byproducts, wheat germ and bran, were collected to feed animals

therefore underutilized. Hence, aim of this thesis was utilization of byproducts from wheat

milling industries at industrial level (produced cookies from blend of wheat germ after

defatted and a non caffeine tea substitute from wheat bran) help to attempt the shortage of

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wheat by developing composite products and insures food security in the country. By

creating awareness in consumer’s mind; commercialization and promoting healthier products

should be given attention.

1.3 Objectives of the study

General objectives

The general objective of this research was to utilize byproducts from wheat milling industries

for development of value added products.

Specific objectives

The specific objectives of this research were to:

Assess the proximate composition of raw materials: wheat germ flour, defatted wheat germ

flour, wheat flour and identify if defatted wheat germ flour was able to supplement wheat

flour to develop last product cookies.

Evaluate mineral contents of wheat flour and defatted wheat germ flour and the composite

cookies developed.

Evaluate rheological properties of control and blended flours.

Determine the functional property of blended flours and control.

Determine the effect of baking temperature and blend ratios on the proximate composition,

physical as well as organoleptic property of cookies

Evaluate the antioxidant property of wheat bran

1.4 Limitation of the study

Even though the research has reached its aspire, there were some avoidable limitations. The

first one is scarcity of byproducts that are used as raw materials for the development of the

value added products i.e wheat germ and wheat bran separately. Because most industries here

avoid those byproducts together for animal feed; but Hora food complex was willing to open

the accurate pipes in the middle of processing the kernel to wheat flour. The second limit was

means of knowing the amount & which specific amino acids present in the defatted wheat

germ flour however there wasn't means of knowing all the amino acids present inside the

wheat germ protein content from nitrogen was calculated.

1.5 Significance of the study

This research studied the importance of utilization of cheap byproducts (wheat bran and

germ) from wheat milling industries. Hence, the final refined white flour resulted in most of

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the industries in Ethiopia; do not pass through enrichment process unlike the developed

countries. This as a result leaves the society poor in nutrition, and the industries less

profitable; instead of utilizing these byproducts either to maximize resource (by blending

with defatted wheat germ flour) or bran as raw material for tea substitute. Utilizing wheat

germ in baked products will not only explore its functional and neutraceutical role but also

contribute towards value addition in wheat milling sectors so that consumers benefit

nutritionally. This indirectly encourages cosmetic industry sectors to make use of oil from

that of defatted wheat germ instead of importing expensive goods from abroad. Finally a new

idea and practices to develop a non caffeine tea substitute from antioxidant rich wheat bran.

Overall outcome of the research will raise profit, creates awareness and give alternatives for

processors especially contribute its part to achieve food security.

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CHAPTER TWO

Literature Review

2.1. Over view on cereals

A cereal is a grass cultivated for the edible components of its grain, composed of endosperm,

germ and bran. Cereal grains are grown in greater quantities and provides more food energy

worldwide than any other type of crop, they are therefore called staple crops. World cereal

production would fractionally decline from the 2013 peak. According to FAO, 2014

estimated wheat production is 721.12 million metric tons achieving a new record from 715.13

million tons last year represent an increase of 5.98 million tones of wheat production around

the globe.

According to USDA report, Ethiopia is the second largest wheat producing country in Africa

next to South Africa. Hence, among major grain crops grown in the country are teff, wheat,

maize, barley (categorized as primarily cool weather crops) and maize, sorghum, and millet

(categorized as warm weather grain crops). It ranks fourth after teff, maize and sorghum in

area coverage and third in total production. Wheat is mainly grown in the central and south

eastern highlands during the main (Meher) rainy season (June to September) and harvested in

October-November. Arsi, Bale, and parts of Shoa are considered the wheat growing belt. In

Ethiopia there has been a substantial growth in yield and production of cereals since 2010. In

2013/14, the yields are estimated to be 2.2 MT/ha. However, by international standards such

yields are considered to be low (Carlos and Doyle, 2009).

0 25,000,000 50,000,000 75,000,000 100,000,000 125,000,000 150,000,000

Metric tons of production

Teff Barley Wheat Maize Sorghum

Figure2.1 Production of key crops from 2010-2013.

2011/12

2010/11 34,834,826

34,976,894

17,033,465 28,556,817

29,163,336

49,861,254

60,694,130 15,852,869

39,598,973

39,512,942

2012/13 37,652,411 34,347,061 61,583,175 17,816,522 39,598,973

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2.1.1 Wheat Consumption and Production in Ethiopia

In Ethiopia, Wheat ranks fourth in terms of area production and yield among food crops.

Production of wheat increased from 2.2 (000 t) in 2004/2005 (CSA, 1998) to 2.8 (000 t) in

2010/2011 (CSA, 2000) an increase of 31 percent. However, the share of wheat in total cereal

area decreased (-12.4 percent) over the same period, mainly due to a shift in cropping

patterns towards sorghum. Wheat yield in Ethiopia is also lagging behind other major

producers in Africa: average yield was 1.68 t/ ha during the same period, about 32 percent

and 39 percent below Kenyan and South African averages, respectively (FAOSTAT). The

apparent low productivity can be attributed to several factors, including slow progress in

developing wheat cultivars with durable resistance to diseases, and depleted soil fertility

(Demeke, 2013).

Commercial imports of wheat have increased in the last couple of years, which is likely the

result of the government’s efforts to stabilize wheat prices following a significant increase in

domestic food prices. Ethiopia remains one of the largest recipients of food aid in Africa,

receiving around 27% of the global food aid given to sub-Saharan Africa. In May 2012/13,

Ethiopian Grain Trade Enterprise (EGTE) imported 322,415 MT of wheat, primarily from

India, 26 percent of which was from the US and from food aid too (Demeke, 2013).

There are around 216 flour mills in Ethiopia, with a total production capacity of about 4.2

million tons of wheat flour a year. Almost a third of these mills are located in Addis Ababa.

Mills are able to obtain wheat through two channels, namely subsidized wheat from the

EGTE and from domestic production on the open market, whose price is higher than imports.

The state-owned EGTE controls all commercial wheat imports and makes wheat available to

millers at a subsidized price; this accounts for roughly a quarter of the wheat market and the

rest of the market is supplied from domestic production, whose price is not controlled and

whose price is higher than imported wheat (Abu, 2014).

It accounts for about 11% of the national calorie intake. The largest volume of the main

season production of wheat originates from Oromia (55 per cent), Amhara (29 per cent) and

the Southern Nations, Nationalities, and Peoples Region, SNNPR (9 per cent) (CSA, 2010).

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2.1.2 Use s and varities of wheat

Uses of wheat

In Ethiopia, wheat grain is used in the preparation of a range of products such as: the

traditional pancake (“injera”), bread (“dabo”), local beer (“tella”), porridge and several others

local food items (i.e., "dabokolo","genfo", "kinche”). Besides, wheat straw is commonly used

as a roof thatching material, and as a feed for animals. Wheat contributes approximately 200

kcal/day in urban areas and about 310 kcal in rural areas.

Globally, there is no doubt that the number of people who rely on wheat for a substantia l part

of their diet amounts to several billions. According to P. kumar et al journal wheat, as

produced by nature, contains several medicinal virtues and relevant to human being discussed

as follow:

Every part of the whole wheat grain supplies elements needed by the human body. Wheat

bran is used as a supplemental source of dietary fiber for preventing colon diseases (including

cancer), preventing gastric cancer, helps constipation by speeding up the colon and increasing

stool output and bowel frequency. Treating irritable bowel syndrome, reducing the risk of

breast cancer and gallbladder disease, and type 2 diabetes

The germ forms only 3% of the weight of a wheat grain; nonetheless, contains about 25% of

the protein, lecithin, vitamins and minerals. Its oil is highly rich unrefined oil, richest sources

of vitamin E, A and D, has a shelf life nearly 6-8 months. This oil widely used for external

application, as it helps a great deal in getting rid of skin irritation including skin dryness and

cracking, improves the circulation of blood and helps to repair the skin cells destroyed by the

scorching heat of sun, has exceptional nourishing qualities, as a result; increasingly finding

its way in the making of skin care products. Wheat germ oil is known for its antioxidant

properties, a good source of fatty acids that are very vital for the healthy growth of the body

and this explains the reason why it is added to other carrier oils. It keeps away the symptoms

of dermatitis, thereby preventing the skin from being victimized by various kinds of

problems.

Wheat grass therapy can be effectively used for skin diseases and ulcerated wounds as by

retarding bacterial action, it promotes cell activity and normal re-growth. By drinking wheat

grass juice regularly, an unfavorable environment is created for bacterial growth. Poultice of

wheat grass juice can be applied on the infected area, as it is an able sterilizer. Externally,

wheat flour is useful as a dusting powder over inflamed surface as in burns, scalds and

9

various itching and burning eruptions, Whole wheat flour, mixed with vinegar, boiled and

applied outwardly removes freckles.

The young stem of wheat used in the treatment of biliousness and intoxication. The ash is

used to remove skin blemishes. The fruit is antipyretic and sedative. The light grain is

antihydrotic. It is used in the treatment of night sweats and spontaneous sweating. The seed is

said to contain sex hormones and has been used in China to promote female fertility. The

seed sprouts are antibilious, antivinous and constructive. They are used in the treatment of

malaise, sore throat, thirst, abdominal coldness and spasmic pain, constipation and cough.

The plant has anticancer properties also.

The straw has many uses, as a biomass for fuel, for thatching, as mulch in the garden. A fiber

obtained from the stems is used for making paper. The stems are cut into usable pieces and

soaked in clear water for 24 hours. They are then cooked for 2 hours in lye or soda ash and

then beaten in a ball mill for 1½ hours in a ball mill. The fibers make a green-tan paper. The

starch from the seed is used for laundering, sizing textiles, etc.

Antioxidants in wheat bran exist in the forms of vitamins (tocopherols – vitamin E), minerals

(selenium), phenolic acids (ferulic acid, vanillic acid), tocotrienols, phytic acid, phytosterols,

flavonoids, and carotenoids (lutein) (El-Sayed et al., 2008). Coffee and tea contain abundant

levels of antioxidants as do wheat and barley kernels. Coffee and tea also naturally contain

caffeine. Coffee and tea substitutes made from wheat and barley have been produced for a

century; however, limited research has gone into the antioxidant benefits from roasted wheat

and coffee beverages.

Species and varieties of wheat

Today wheat is one of the world’s most important grains, as it covers more of the earth’s

surface than any other grain crop. Wheat is a cereal grain of the genus Triticum within the

grass family Poaceae. Botanically, there are more than 30, 000 wheat varieties, categorized

into six major classes according to planting and harvesting dates as well as hardness, color

and shape of the kernels(Kelly, 2009): Wheat varieties included were (i) Hard or soft, which

relates to the hardness of the kernel. (ii) Red or white, which relates to the presence or

absence of a red pigment in the outer layers of the wheat kernel. (iii) Winter or spring wheat

varieties that are categorized as such depending on when the wheat is planted.

Ethiopian farmers traditionally grow several varietal mixtures (even less productive cultivars

and wild relatives) in the same field that might have advantage to add variety to their diet,

10

reduce the risk of pests and diseases or unusual environmental conditions, and also preserve

cultivars and genetic diversity (Bekele, 1984; Jain, 2000). Ethiopian wheat includes tetraploid

and hexaploid species. Tetraploid wheats are indigenous, whereas hexaploid wheats are

probably a recent introduction (Bechere, 2000). In wheat breeding history Ethiopian

tetraploid wheat landraces were often used as sources of earliness, disease and pest

resistance, nutritional quality, resistance to drought and other stresses, adaptation to low soil

fertility and other characteristics useful in low-input agriculture (Worede, 1997).

Durum wheat is of the species Triticum durum distinctly different from common wheat in

that it produces very hard kernels and has yellow pigments throughout the endosperm rather

than in the outer layers. It is typically used to produce pasta products, while common wheat is

used, for example, in breads, cakes, cookies, and crackers (Korolchuk et. al., 2006). The

species according to Ministry of agriculture and rural development, (2009) can be categorized

as:

Hexaploid species

Common wheat or Bread wheat (T. aestivum) is hexaploid species that is the most widely

cultivated one in the world. Spelt (T. spelta) is another hexaploid species cultivated in limited

quantities. Spelt is sometimes considered a subspecies of the closely related species common

wheat (T. aestivum), in which case its botanical name is considered to be Triticum aestivum

subsp. spelta. Among the different varieties of bread wheat in Ethiopia that have been

currently developed to satisfy the growing production demands are: Tura, Sirbo, Bobicho,

Tossa, Sofumar, Digalu, Senkegna, Dinknesh, Alidoro, Menze, Meraro, Warkaye,

Dereselgne, Dashen, Mitike, Kubsa, Wabe, Galema, Megala, Abola, Tuse, Simba, Katar,

Shina, Wetera, Gasay, Sulla, Meraro, Warkaye, Jiru, Senkegna, Millennium.

Tetraploid Species

Durum (T. durum) – The only tetraploid form of wheat widely used today, and the second

most widely cultivated wheat. It has very narrow adaptation and lower yield potential as

compared to bread wheat includes: Hitosa, Denbi, Werer (Mamouri I), Tate, Flakit, Obsa,

Ejersa, Bakalcha, Kokate, Malefia, Oda, Ilani, Megenagna, Quami, Mettaya, Ude, Selam,

Ginchi, Robe, Laste , Asasa, Arsi-Robe, Mosobo .

Emmer (T. dicoccum) is also tetraploid species originated in the Near East., cultivated in

ancient times but no longer in widespread use worldwide. Indeed, it is one of the first cereals

ever domesticated and was part of the early agriculture of the Fertile Crescent.

11

Diploid Species

Einkorn (T. monococcum) is diploid species with wild and cultivated variants. Domesticated

at the same time as emmer wheat, but never reached the same importance.

Triticale (X-Triticosecale)

This one is a man-made crop developed by crossing wheat (Triticum turgidum or Triticum

aestivum) with Rye (Secale cereale). In Ethiopia triticale is only a recent introduction:

Dilfekar, Logaw Shibo, Minet, Snan.

2.1.3 Morphology and composition of wheat

Wheat grains are generally oval shaped, although different types of wheat have grains that

range from almost spherical to long, narrow and flattened shapes. The grain is usually

between 5 and 9mm in length, weighs between 35 and 50mg and has a crease down one side

where it was originally connected to the wheat flower. The wheat grain contains 2-3% germ,

13-17% bran and 80-85% mealy endosperm (all constituents converted to a dry matter basis)

(Zuzana et al, 2009).

The wheat kernel consists of three fractions, the endosperm, bran, and germ, which are

compositionally and morphologically very different. Thus, products will have different

coarseness, textures, and color depending on the portion of the wheat kernel being used.

Refined wheat flour is formed primarily from the endosperm of the wheat kernel. The

endosperm comprises approximately 82% of the wheat kernel. The function of the endosperm

is to provide energy for the embryonic plant during germination of the wheat kernel. The

endosperm contains approximately starch and 10-14% protein (Korolchuk et al., 2005).

Compared to the bran and germ, the endosperm contains low amounts of fiber, lipid,

vitamins, minerals, protein, pigments and other phytonutrients. This helps give the refined

wheat flour its consistent, fine, starchy texture and off-white color compared to whole-grain

wheat flour. The bran consists of several cell layers and contains a significant amount of

fiber. The bran includes the aleurone layer, which separates the endosperm from the bran

layers. The aleurone layer is rich in proteins, vitamins and phytonutrients. The germ is rich in

lipids, fiber, vitamins, minerals and phytonutrients. Thus, refined wheat flour, which is made

primarily of endosperm is mainly starch and has limited amounts of fiber, proteins, lipids,

vitamins, minerals and other phytonutrients (Korolchuk et al., 2005).

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Figure 2.2 Schematic diagram of wheat (Surget and Barron, 2005).

The bran (outer layers of wheat grain) is made up of several layers, which protect the main

part of the grain. In order to protect the grain and endosperm material, the bran comprises

water-insoluble fiber. Chemical composition of wheat bran fiber is complex; it contains,

essentially, cellulose and pentosans, polymers based on xylose and arabinose, which are

tightly bound to proteins. These substances are typical polymers present in the cell walls of

wheat and layers of cells such as aleurone layer. Proteins and carbohydrates each represent

16% of total dry matter of bran. The mineral content is rather high (7.2%). The two external

layers of the grain (pericarp and seed coat) are made up of dead empty cells. The cells of the

inner bran layer- aleurone layer are filled with living protoplasts. There are large differences

between the levels of certain amino acids in the aleurone layer and those in flour. Glutamine

and proline levels are only about one half, while arginine is treble and alanine, asparagine,

glycine, histidine and lysine are double those in wheat flour (Cornell 2003).

2.2 Effect of milling process

The consumption of white flour and bread have historically been associated with prosperity

and the development of sophisticated roller mills in Austro-Hungary during the second part

of the 19th century allowed the production of higher volumes of whiter flour than it was

possible to produce by traditional milling based on grinding between stones and sieving. The

bleached flour obtained at the end of the product is not rich in nutrient; however the by-

products obtained are excessively prosperous to be left for animal feed (Jones, 2007).

Generally, cereal grains are subjected to different processes to prepare them for human

consumption. These processes significantly affect their chemical composition and

consequently their nutritional value. Flour processing decreases the levels of naturally

13

occurring, non -bioavailable nutrients in flour. Iron and folic acid are among the vitamins and

minerals lost when bran and germ are separated from endosperm (Victor, 2011).

Table 2.1 Wheat composition and the milling process effect on nutrient composition

Items Wheat grain Bran Flour Germ

Dietary fiber (g) 12 42.8 2.7 13.2

Protein (g) 15.4 15.5 10.3 23.1

Amino acids

Tryptophan (mg) 195 282 127 317

Threonine (mg) 433 500 281 968

Isoleucine (mg) 541 486 357 847

Leucine (mg) 1038 928 710 1571

Lysine (mg) 404 600 228 1468

Methionine (mg) 230 234 183 456

Cystine (mg) 404 371 219 458

Phenylalanine (mg) 724 595 520 928

Tyrosine (mg) 441 436 312 704

Valine (mg) 679 726 415 1198

Arginine (mg) 702 1087 417 1867

Histidine (mg) 330 430 230 643

Alanine (mg) 555 765 332 1477

Aspartic acid 808 1130 435 2070

Glutamic acid (mg) 4946 2874 3479 3995

Glycine (mg) 621 898 371 1424

Proline (mg) 1680 882 1198 1231

Serine (mg) 663 684 516 1102

Vitamins

Thiamin (mg) 0.5 0.5 0.1 1.9

Niacin (mg) 5.7 13.6 1.3 6.8

Vitamin B6 (mg) 0.3 1.3 - 1.3

Folate (µg) 43 79 26 281

Therefore, milling removes the fibrous layers of the grain; thus, refined cereals do not have

the same nutritional and health benefits as the grain or by-products. Without the bran and

Source: Gramene (2009)

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germ, approximately 45% of the grain proteins are lost, along with 80% of fiber, 50 -85% of

vitamins, 20-80% of minerals, and up to 99.8% of phytochemicals. In addition, important

losses of amino acids (35-55%) occur during refining. Some fiber, vitamins, and minerals

may be added back into refined cereal products through fortification or enrichment programs,

which compensates for losses due to refining, but it is impossible to restore the

phytochemicals lost during processing (Rosell, 2007).

2.3 Phytochemicals and antioxidants

Phytochemicals

Two hundred and ten thousand phytochemicals present in plants have been isolated and

characterized according to the Dictionary of Natural Products (Hampden Data Services Ltd.,

2008) but a large percentage of phytochemicals remain unknown. ‘Phytochemical’ refers to

every naturally occurring chemical substance present in plants, especially those that are

biologically active (Zielinski and Kozlowska, 2000).

Wheat grains are sources of phytochemicals with potential health benefits. Phytochemicals

together with many other micronutrients are often found in the germ and the bran of wheat.

Though, wheat bran and germ layers removed during milling contain 75% of the phytonutrients

(Slavin, 2003; Jones et al., 2004) in the wheat kernel.

Wheat grain, particularly, its bran fraction contains several classes of phytochemicals. Among

them, phenolic acids, polyphenols (flavonoids and lignans), (both phenolic acids and flavonoids

are major class of phytochemicals containing one or more aromatic ring and one or more

hydroxyl group), carotenoid (another group of phytochemicals contributing to the pigments and

are thought to provide health benefits in decreasing the risk of disease, particularly certain

cancers and eye diseases), tocopherol/tocotrienols (used for treating diabetis, desease of brain and

nervous system, to avoid complication in late pregnancy, to prevent aging etc.), and

phytosterols/phytosterols (a group of phytochemicals known for cholesterol reduction in human

have been characterized and linked to many bioactivities related to human health). Most of these

phytochemicals have shown strong antioxidant activities in both pure and mixed forms also have

been implicated to play a protective role against chronic diseases such as cancer, cardio-vascular

diseases, and diabetes (Liang, 2007).

Antioxidants

Antioxidants are substances that may protect the cells against the effects of free radicals or

compounds that detoxify reactive oxygen species (ROS) and prevent their damage through

15

multi mechanisms. Oxidation reactions can produce free radicals and these radicals are

responsible to vast variety of human diseases including atherosclerosis, arthritis, ischemia

diabetic mellitus, hypertension, aging, and cancer. Synthetic antioxidants have been in use as

food additives for a long time, but reports on their involvement in chronic diseases have

restricted their use in foods. It is established that consumption of antioxidant substances has

been linked to the reduction in the incidence of oxidative-stress related diseases. The use of

currently available synthetic antioxidants like butylated hydroxy anisole (BHA), butylated

hydroxyl toluene (BHT) has been limited due to their toxicity and side effects. They are

suspected of being responsible for liver damage and carcinogenesis in laboratory animals.

Hence strong restrictions have been placed on their application and therefore research for the

determination of the natural oxidants source is important (Tapan et. al., 2013 and Magdy et

al., 2014).

They play many important roles such as free radical scavenger, reducing agent and

antioxidant defense enzyme system activator. Rice and wheat are two very commonly

consumed cereal grain that contain several antioxidative compounds and are shown to be

beneficial for a wide range of medical conditions (Bishwajit et. al., 2013).

Antioxidants terminate ROS attacks and appear to be of primary importance in the prevention

of these diseases and health problems. It has been widely accepted that diet can significantly

alter the overall health and quality of life. Development of functional foods rich in

bioavailable antioxidants may play an important role in this regard. The key for developing

functional foods is to provide a sufficient amount of the bioavailable safe active components,

the functional additives/nutraceuticals, in the finished functional food products (Liangli,

2007).

Antioxidant activity is an important biological property of many phytochemicals that protects

living organisms from oxidative damage thereby preventing various deleterious events and

diseases in plants and animals including human beings. Phenolic compounds possess

antioxidant activity and these are aromatic secondary metabolites of phenylalanine, and, to a

lesser extent, tyrosine that constitute one of the most diverse family of compounds found in

plants. Simple phenols, phenylpropanoids, flavonoids, tannins (proanthocyanidins and

others), and lignins are among numerous categories of plant phenolics. Cereals have been

known to contain phenolic acids, phytoestrogens, and small quantities of flavonoids. The

phenolic acids in cereals are benzoic and cinnamic acid derivatives; the latter being most

16

common. Cereals are also a major source of dietary lignans with potent antioxidant activity

(Liangli, 2007).

Phenolic acids exist as free, esterified and insoluble-bound forms. One of the advantages of

bound phytochemicals is their ability to survive digestion in the upper gut, allowing them to

reach the colon and, therefore, exert health benefits. Flavonoids and phenolic acids are

examples of antioxidants, which are important ingredients of many foods, and keenly sought

in many ‘health foods’. They are thought to help protect against diseases like cancer,

cardiovascular disorders, neurodegenerative diseases and ageing by mopping up potentially

damaging free radicals that are released in the body (Asli et al., 2010).

Postum is a powdered roasted-grain beverage once popular as a coffee substitute. The

caffeine-free beverage was created by Postum Cereal Company founder 1895 and marketed

as a healthful alternative to coffee. The Postum Cereal Company eventually became General

Foods, which was bought by Kraft Foods. Post was a student of John Harvey Kellogg, who

believed that caffeine was unhealthy. The "instant" drink mix version was developed in 1912,

replacing the original brewed beverage Postum is made from wheat bran, wheat, molasses,

and maltodextrin from corn (Pendergrast and Mark, 2010). The tea substitute made in this

research paper only shared the wheat bran part from postum neither used the molasses nor

corn instead wheat bran stimulated by natural non caffeine herb /additives like mint,

Cinnamon, funnel seed used as extra flavor for the drink when steeped in hot cup water.

The main characteristic of an antioxidant is its ability to trap free radicals. Highly reactive

free radicals and oxygen species are present in biological systems from a wide variety of

sources. These free radicals may oxidize nucleic acids, proteins, lipids or DNA and can

initiate degenerative disease (Aruna et al., 2014).

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2.4 Raw materials for developed products

2.4.1Wheat bran

Bran, an outer layer of most cereal grains, is nutrient dense as it contains proteins, omega 3

and omega 6 fatty acids and antioxidants. Cereal bran is an excellent source of dietary fiber;

for addition to food, it offers all the nutritional and neutraceutical benefits. It contributes a

pleasing sweet, nutty flavor when added as a flavor enhancer in baked products and pasta. It

is obtained from screened grains of wheat (Muhannad, 2010).

Wheat bran is a major by-product of the wheat milling industry used in value added products;

the majority of it is used as animal feed and therefore underutilized. Wheat bran is known to

contain many phytochemicals with numerous health benefits. wheat bran extracts have

greater bioactivity than endosperm wheat extracts, suggesting that this major by-product of

Figure 2.3 Free radicals and disease.

Source: Pearson Education Inc. Publishing as Benjamin Cummings (2005).

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the flour milling industry is highly nutritious, and contributes to the known health benefits of

wheat for humans. Wheat extracts have shown high antioxidant activity, binding free radicals

to promote healthy aging, and reduce risk of cardiovascular disease, diabetes and obesity, as

well as some forms of cancer. Wheat bran had the highest level of antioxidant activity which

was found by bioassay guided fractionation to be attributed to the unsaturated fatty acids;

linolenic, linoleic and oleic acids (Kelly, 2009).

Wheat bran contains strong antioxidant activity. It may therefore provide protection against

aging, cardiovascular disease, cancer, diabetes and obesity. The amino acid tryptophan was

the prominent cause of the antioxidant activity observed in durum wheat bran. Wheat bran

has been reported to contain 75% of the phytochemicals present in wheat, but the bioactivity

and chemical identity of these phytochemicals is largely unknown (Kelly Marie, 2009).

The antioxidant activity of wheat is derived mainly from the bran layers, with compounds

found in the endosperm playing a minor role. Many studies have assessed wheat antioxidant

activity with speculation on bioactives. A study of antioxidant activity from six milling

fractions including head shorts, tail shorts, low-quality flour, low-grade flour, bran and

control flour, showed that bran possessed the greatest antioxidant activity compared to all

these samples. This is further supported by Adom et al. (2005), who found antioxidant

activity of a bran/germ fraction, from milled fractions of different wheat varieties, had 13–27

fold increase in antioxidant activity compared to the endosperm in the hydrophilic assay

(Kelly Marie, 2009).

Antioxidants in wheat exist in the forms of vitamins (tocopherols – vitamin E), minerals

(selenium), phenolic acids (ferulic acid, vanillic acid), tocotrienols, phytic acid, phytosterols,

flavonoids, and carotenoids (lutein). About 36 Wheat species have widely differing quantities

of antioxidants. Antioxidant content in modern white wheat varieties has tested to be lower

than antioxidant content in modern red wheat varieties. Coffee and tea contain abundant

levels of antioxidants as do wheat and barley kernels. Coffee and tea also naturally contain

caffeine. Coffee and tea substitutes made from wheat and barley have been produced for a

century; however, limited research has gone into the antioxidant benefits from roasted wheat,

or from it’s by products. As the benefits of wheat and barley antioxidants become better

known, the wheat and coffee beverage markets may emerge as well. (Neil et. al, 2012)

Recovery of antioxidant compounds from plant materials is typically accomplished through

different extraction techniques taking into account their chemistry and uneven distribution in

the plant matrix. For example, soluble phenolics are present in higher concentrations in the

19

outer tissues (epidermal and sub-epidermal layers) of fruits and grains than in the inner

tissues (mesocarp and pulp). Solvent extraction is most frequently used technique for

isolation of plant antioxidant compounds. However, the extract yields and resulting

antioxidant activities of the plant materials are strongly dependent on the nature of extracting

solvent, due to the presence of different antioxidant compounds of varied chemical

characteristics and polarities that may or may not be soluble in a particular solvent. Polar

solvents are frequently employed for the recovery of polyphenols from a plant matrix. The

most suitable of these solvents are (hot or cold) aqueous mixtures containing ethanol,

methanol, acetone, and ethyl acetate (Neil et al., 2012).

2.4.2 Wheat germ

Wheat germ, a part of the wheat kernel removed as by-product of the wheat milling industry,

is considered as a natural source of highly concentrated nutrients (Shao and LiYa, 2011). The

wheat germ is a unique source of concentrated nutrients, highly valued as food supplement.

While the oil is widely appreciated for its pharmaceutica,l nutritional and cosmetic value, the

defatted germ meal is a promising source of high-quality vegetable proteins. The germ is only

a very small part of the kernel, approximately 3 percent in total. Wheat germ is very high

(around 28 percent proteins) (Finely, 1989; Bruce, 1997).

The amount of nutrients that are contained within wheat germ seems endless. It contains

more potassium and iron than any other food source. Also found in great quantities are

riboflavin, calcium, zinc, magnesium and vitamins A, B1 and B3. Vitamins B1

and B3are very

important to maintain energy levels and maintain healthy muscles, organs, hair and skin.

Another important vitamin found in wheat germ is vitamin E; which is a very important

antioxidant. It is helpful in preventing the body's aging process and also to prevent heart

disease, helps to prevent blood clots and is needed to strengthen the body’s immune system.

Wheat germ has been found to be very beneficial in order to keep the body in tip top

condition. It is used by athletes in their diet to improve cardiovascular function and improve

endurance levels (Sabate, 1993; Spiller, 1997). Body builders will also add wheat germ to

their diets in order to bulk up and maintain the nutritional levels they need to perform (Neli et

al., 2007).

Wheat germ also contains some relatively functional phytochemicals such as flavonoids,

sterols, octacosanols, and glutathione. It provides three times as much protein, seven times as

much fat, 15 times as much sugar and six times as much mineral content than wheat flour.

20

Wheat germ protein has been classed effectively with superior animal proteins and is rich in

amino acids, especially the essential amino acids lysine, methionine, and threonine, in which

many cereals are deficient (Shivani and Sudha, 2011). Wheat germ oil is used in products

such as foods, biological insect control agents, pharmaceuticals and cosmetic formulations

(Alessandra et al., 2009). It is a good source of healthy fatty acids that help lower cholesterol,

lower inflammation, and supports a healthy nervous system which can lower anxiety levels

and improve mood (Pinna and Peter, 2009).

Table 2.2 Fatty acid composition of wheat germ oil

Fatty acid %

Palmitic acid 17.4

Stearic acid 0.9

Oleic acid 17.1

Linoleic acid 56.1

Linolenic acid 6.9

Arachidonic acid 0.2

Eicosenoic acid 1.4

Source: Asuman Kan, (2012).

Stabilizing wheat germ by defatting increased the protein content to 38% and also increased

the soluble fiber from 2.07 to 3.01% and insoluble fiber increased from 14.4 to 24.49%

(Bansal and Sudha 2011). Defatted wheat germ is the ideal ingredient for grain based food

products. Natural and nutritious, it enhances the flavor and texture of hundreds of

applications. Wheat germ is processed to retain the natural nutritional and flavor

characteristics of fresh, high quality wheat germ. The functional qualities of each include

improving the stability texture, nutritional value and flavor of processed foods and consumer

goods of all kinds. Each is high in protein and fiber and is virtually fat free. The product is

granular and possesses a toasty mocha- like flavor (Garuda, 2011).

According to IFIC food and health Survey of 2013 defatted wheat germ helps meet today’s

demands for full flavor grain-based foods that are rich in protein and fiber. This

multidimensional ingredient offers 26%+ protein, 15%+ fiber, Low fat, 12-month shelf life

and a multitude of vitamins and minerals. Defatted Wheat Germ improves nutrition, enhances

flavor and enriches the texture for your end product.

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2.5 Process description

2.5.1 Process description for wheat flow

A modern milling operation involves much more than grinding wheat to a powder. Three

general operations are usually involved: cleaning, tempering, and milling. Cleaning removes

unwanted material; tempering softens the grain, making it easier to separate and grind; and

milling involves grinding the wheat and isolating wheat components of a specific size.

i. Cleaning

Wheat unloaded from a truck, into a mill elevator contains a sizable percentage of non wheat

kernel components, termed “dockage.” Dockage consists of other types of seeds,

underdeveloped or unsound wheat kernels, insects, stems, stones, and other debris commonly

found in a wheat field. Before milling, this debris must be removed, and this is accomplished

in the wheat cleaning section of the mill. Although numerous machines exist to clean wheat,

they are all classified based on separation by size, shape, density, and magnetism. Different

mills vary greatly with respect to the order of the operations in a cleaning process. Usually,

one of the first separations removes any ferrous metal in the wheat using magnetic separators.

Removing metal early in the process helps avoid damage to equipment farther downstream.

A milling separator may be next, to remove sticks, stones, stems, and other plant debris.

Lighter, less-dense components in the wheat are removed here via aspiration. Air circulates

upward through the grain as it is fed into the separator, and lighter material is drawn away

from the wheat kernels. The wheat then falls onto a sieve, which allows the wheat to pass

through but retains stones and larger seeds. Another sieve follows which retains the wheat

and allows smaller seeds to pass through.

A disk separator, which separates wheat from other grains of equal density, is also likely to

be included in the cleaning process. This machine separates grains based on shape. Pockets in

rotating disks accept seeds of certain lengths and reject those of other sizes. Generally there is

more than one disk separator. One will accept wheat and another will reject wheat to remove

both larger and smaller grains. Dirt or mold adhering to wheat kernels is largely removed

using a scourer. This machine uses a screen or an abrasive surface to remove any material

adhering to the kernel. Materials such as small stones similar in size to a wheat kernel are

separated based on density in a gravity table or dry stoner. The gravity table is an oscillating

inclined plane. Denser material such as stones moves down the table faster than lighter

22

material. The dry stoner removes the dense material with aspiration sufficient to raise the

grain and allow the stones to drop out.

ii. Tempering:

is the addition of predetermined amounts of water to wheat during specific holding periods. It

toughens the bran, making it easier to separate from the endosperm and germ. It also softens

the endosperm, allowing it to break apart with less force. Tempering involves adjusting the

moisture level of the wheat. For soft wheat, optimal tempering brings the grain to 13.5–

15.0% moisture and takes 6–10 hr. For hard wheat, the final moisture is 15.5–16.5%, and

tempering times are 12–18 hr. Incoming wheat is generally lower in moisture content than

this; hence, water is usually added and the grain is allowed to equilibrate for a period of time.

This time varies considerably based on the hardness of the wheat. Conditioning of wheat

refers to the application of heat in the tempering process to increase the rate of penetration of

moisture into the kernels. Temperatures lower than 50°C are employed during conditioning to

ensure that the functionality of the flour components, especially the gluten, is maintained.

iii. Milling:

At this point, the wheat is ready for milling and starts through the various systems in the

mill. The first machine in almost every mill is the roller mill. Two rolls, one rotating

clockwise and the other counterclockwise, are separated by a small distance called the “gap.”

One of the rolls usually rotates faster than the other one. Consequently, at the nip, due to the

rotation of the rolls the wheat experiences a shearing action as well as a crushing action.

The first roller mills are employed in the break system. This is the part of the milling

operation designed to remove the endosperm from the bran and germ. Rolls in this process

have spiral grooves called “corrugations” cut parallel to the long axis of each roll. Generally

there are about five roller mills or five “breaks” in the system. The germ is removed in the

first two breaks, as is much of the bran. The germ is pliable and tends to flatten when it goes

through the rollers. Bran particles are usually in the form of low-density small flakes. These

properties allow millers to separate the germ and bran fractions from the endosperm fraction.

After each break, a set of sieves and/or purifiers (aspirators) separates the ground material by

size and density.

23

iv. Sieving:

Small particles are channeled into the flour, and large particles are either removed (as is the

case with the germ and bran) or sent to the next break (as occurs for large endosperm pieces).

Once the endosperm is isolated, the large particles that result (called middlings) are reduced

in the reduction system to a particle size distribution consistent with flour. This means they

must be able to pass through a 136-μm opening. The rollers in the reduction system are

smooth and are operated at low differentials, providing a crushing action that yields the fine

particles of flour (although a small amount of shear is still important). A large percentage of

the particles composing the final flour come off the reduction rolls.

Flour from the break and reduction rolls may be combined in many ways to create different

types of flour, but it is usually sifted again in the flour dressing system and passes through

sieves meets the particle size standard for flour. Larger particles are recirculated back to the

appropriate point in the grinding process. The flour may be further treated with chlorine or a

bleaching agent depending on the requirements of the customer. In the mill feed system, the

germ and bran are separated from each other, and adhering endosperm is removed. The

coarse bran from the early breaks is termed “bran” and composes about 11% of the total

products from the mill. The finer branny material from the later steps is called shorts; it

represents about 15% of the total. Germ is generally recovered at the rate of about 2–3.0% of

the total wheat depending on the type of equipment used. These special products or

ingredients for human consumption are usually sold as animal feed in our country. The steps

were shown in Fig 2.4 Process steps in wheat milling.

24

Figure 2.4 Process steps in wheat milling.

Source: School of Biological Sciences, University of Bristol, England (2007)

25

2.5.2 Process description for biscuit production

Defatting process by supercritical fluid extraction

There are several methods for oil extraction that all have their advantages and disadvantages.

Mechanical expression (pressing) and organic solvent extraction are both being used for

commercial extraction of wheat germ oil (WGO). Solvent extraction is by far the most widely

used method to extract oil (Woerfel, 1995).

In recent years supercritical fluid extraction (SFE) has received increased attention as an

important alternative to conventional methods.This is due to regulatory and environmental

pressures on hydrocarbon and ozone-depleting emissions. SCF-based processes have helped

to eliminate the use of hexane and methylene chloride as solvents. With increasing scrutiny

of solvent residues in pharmaceuticals, medical products, and neutraceuticals, and with

stricter regulations on volatile organic compounds (VOC) and ozone depleting compounds

(ODC) emissions, the use of SCFs is rapidly proliferating in all industrial sectors.

Supercritical fluids have adjustable extraction characteristics due to their density, which can

be controlled by changes in pressure or temperature. In addition, other properties such as low

viscosity, high diffusivity and low surface tension enhance the solute mass transfer from

inside a solid matrix. SCFs are advantageously applied to increasing product performance to

levels that cannot be achieved by traditional processing technologies, and such applications

for SCFs offer the potential for both technical and economic success (Sultana, et.al, 2007,

Reverchon et. al., and Lang et.al., 2001).

Supercritical carbon dioxide (SC-CO2), being nontoxic, nonflammable, inexpensive and

easily separable from the extracts, has been the most frequently used extractant in the food

and pharmaceutical industries. Furthermore, the low critical temperature of carbon dioxide

allows extraction of thermolabile compounds without degradation (Alessandra et al., 2009). It

is an efficient extraction method, which is non-explosive and non-toxic, leaving non-solvent

residues. The oils extracted with this method do not need the traditional refining processes. In

addition, SFE is a mild process which can avoid fatty acid oxidation and protein in defatted

wheat germ denaturation. Therefore SFE has received increased attention as a promising

alternative to conventional extraction methods over the last decades (Shao and LiYu, 2011).

A supercritical fluid is the phase of a material at critical temperature and critical pressure of

the material. Critical temperature is the temperature at which a gas cannot become liquid as

26

long as there is no extra pressure; and, critical pressure is the minimum amount of pressure to

liquefy a gas at its critical temperature. Supercritical values for these features take place

between liquids and gases. The formation of a supercritical fluid is the result of a dynamic

equilibrium. When a material is heated to its specific critical temperature in a closed system,

at constant pressure, a dynamic equilibrium is generated. This equilibrium includes the same

number of molecules coming out of liquid phase to gas phase by gaining energy and going in

to liquid phase from gas phase by losing energy. At this particular point, the phase curve

between liquid and gas phases disappears and supercritical material appears (Mustafah and

Andrew, 2013).

There is another characteristic point in the phase diagram; the critical point (CP) is obtained

at critical temperature (Tc) and critical pressure (Pc). After the CP, no matter how much

pressure or temperature is increased, the material cannot transform from gas to liquid or from

liquid to gas phase. This form is the supercritical fluid form. Increasing temperature cannot

result in turning to gas, and increasing pressure cannot result in turning to liquid at this point.

In the phase diagram, the field above Tc and Pc values is defined as the supercritical region.

(Mustafah and Andrew, 2013).

Figure 2.4 Schematic representation of idealized phase diagram.

Source: (http://cnx.org/content/m46150/1.2/)

27

According to thermodynamic research laboratories of university of Illinois’ SCFE is

advantageous:

1. SCFs have solvating powers similar to liquid organic solvents, but with higher

diffusivities, lower viscosity, and lower surface tension.

2. Since the solvating power can be adjusted by changing the pressure or temperature

separation of analytes from solvent is fast and easy.

3. By adding modifiers to a SCF (like methanol to CO2) its polarity can be changed for

having more selective separation power.

4. In industrial processes involving food or pharmaceuticals, one does not have to worry

about solvent residuals as you would if a "typical" organic solvent were used.

5. Candidate SCFs are generally cheap, simple and are safe. Disposal costs are much

less and in industrial processes, the fluids can be simple to recycle

6. SCF technology requires sensitive process control, which is a challenge. In addition,

the phase transitions of the mixture of solutes and solvents have to be measured or

predicted quite accurately. Generally the phase transition in the critical region is

rather complex and difficult to measure and predict. Advantages of Using Carbon

dioxide is the most commonly utilized SCF in SFE machine. It is chemically stable,

has relatively low toxicity, is not flammable, is inexpensive and produces zero surface

tension. Furthermore, it has a mild critical temperature required for extraction of

thermolabile compounds and is separated easily from the sample.

Farinograph analysis

The Farinograph is an apparatus which is commonly used to measure the rheological

properties of dough (Inn, et al., 2007). It measures (as torque) and records the resistance to

mixing of dough as it is formed from flour and water (AACC, 2000). Viscoelastic properties

of wheat dough are the result of the presence of a three dimensional net work of gluten

proteins. The Visco-elastic properties enable dough to retain gas which is essential for

production of baked products with a light texture. Rheological properties such as elasticity,

viscosity and extensibility are important in the prediction of the processing parameters of

dough and quality of end product (Hruskova, 2001). Farinograph results include absorption,

arrival time, stability time, peak time, departure time, and mixing tolerance index.

28

Absorption (%): is the amount of water required to center the farinograph curve on the

500 brabender units (BU) line. This relates to the amount of water needed for a flour to

be optimally processed into end products.

Peak Time (minute) - indicates dough development time, beginning the moment water is

added until the dough reaches maximum consistency. This gives an indication of

optimum mixing time under standardized conditions. It is expressed in minutes.

Arrival Time (minute) - is the time when the top of the curve touches the 500-BU line.

This indicates the rate of flour hydration (the rate at which the water is taken up by the

flour). Arrival time is expressed in minute.

Departure Time (minute) - is the time when the top of the curve leaves the 500-BU line.

This indicates the time when the dough is beginning to break down and is an indication

of dough consistency during processing. Departure time is expressed in minutes.

Stability Time (minute) - is the difference in time between arrival time and departure

time. This indicates the time the dough maintains maximum consistency and is a good

indication of dough strength.

Mixing Tolerance Index (MTI) is the difference in BU value at the top of the curve at

peak time and the value at the top of the curve 5 minutes after the peak. This indicates

the degree of softening during mixing. Mixing tolerance index is expressed in Brabender

units(BU). Weak gluten flour has a lower water absorption and shorter stability time than

strong gluten flour.

29

Preparation of value added cookies

The demand for food and agricultural products is changing in unprecedented ways. The

nature and extent of the changing structure of agri- food demand offer extraordinary

opportunities for diversification and value addition in agriculture, particularly in developing

countries. The prospects for continued growth in demand for value-added food and

agricultural products constitute an incentive for increased attention to agro industries

development within the context of economic growth, food security and poverty-fighting

strategies. Agro- industries, here understood as a component of the manufacturing sector

where value is added to agricultural raw materials through processing and handling

operations are known to be efficient engines of growth and development. With their forward

and backward linkages, agro-industries have high multiplier effects in terms of job creation

and value addition (Carlos and Doyle, 2009).

According to New Brunswick Value-added Food Sector Strategy 2012-2016, any step in the

production process that improves the product for the customer and results in a higher net

worth called value addition. Value-added food sector encompasses companies producing

agriculture and seafood-based products, beverages and other food made from both local and

imported resources. The sector includes live, fresh, frozen, packaged, processed and

preserved food products whose value and profitability has been increased by making them

more appealing and valuable to the buyer.

In Ethiopia, the food-processing sector is by far the largest manufacturing industry and

accounts for 39% of the gross value of production in large and medium size manufacturing in

Figure 2.5 Parameters in Pharinograph representation from manual in Kality Factory (1923).

30

2009/2010 which expected to arouse even more by now. The gross value of production

(GVP) equals 16,220 million Birr (900 million USD), of which small-scale manufacturers

achieve a GVP of 308 million Birr in food processing excluding grain milling, and the grain

millers produce a GVP of 1,113 million Birr. The largest sectors are sugar, bakery, and grain

milling, which together cover about 47% of the total GVP (Soethoudt et. al., 2013).

Increasing awareness of consumers regarding health and nutrition has led to

experimentations for modification and development of bakery products to value added health

foods. This may become a boon for further development of bakery products using low cost,

nutritious ingredients. Among these bakery products cookies/biscuits are popular and well

accepted as snack food. ‘Cookie’ is chemically leavened product, also known as ‘biscuit’

(Uma Ballolli, 2010).

Cookies are textural and flavorful wonders, they are easy to make and usually require no

special equipment. Cookie recipes run the gamut from chic and classic to simple, homespun,

and familiar. Cookies are versatile: They can be huge or miniature, chewy or crisp, filled or

frosted or plain, sweet or savory. They can be round, square or rectangular or take the shape

of animal, vegetable, or mineral. They can be kitschy, chic or both at the same time. Many

welcome variations (John, 2002).

The ingredients of cookies are flour, shortening, eggs, salt, leavening agents, additives,

flavors, liquids, and various other enriching ingredients. Each one of these ingredients has its

own role and function in the preparation of the product (Sumnu and Sahin, 2008). The

importance/ function of ingredients used in cookies making are revealed below:

Fat is added for flavor and controls how chewy or crunchy the cookie is. More fat is a

chewier cookie, less fat is a crunchier cookie. Options for fat are butter, margarine,

shortening, or oil. Since shortening melts at a higher temperature, it is the best choice if one

wants to keep spreading to a minimum. Shortening, butter, and margarine are all fats. But not

all fats are created equal when it comes to baking cookies. Fats are used in cookies to:

tenderize and soften the texture, ad moistness and richness, increase the keeping quality, add

flavor, assist in leavening when used as a creaming agent

Sugar is a sweetener (obviously!) and tenderizer, while controlling how much the cookie

spreads. Using white sugar will result in a crispier cookie, while brown sugar will help

retain moisture, making cookies chewier. Adding sugar increases the spread of a cookie, so

cookies with less sugar will be puffier.

31

Flour is a stabilizer and thickener and controls how much the cookie rises. It holds the cookie

together, providing it with its structure. If too little flour used cookie won’t keep its shape but

if one use too much you’ll end up with a thick tasteless cookie. Also, different types of flour

result in different cookie textures. All-purpose flour is the standard flour used most often.

Dough may have a ratio of 1:6 or higher and might be used for cookies or pastry dough.

Rising agent or leavener most commonly used is either baking soda or baking powder. If

baking soda used, recipe must include another acidic ingredient, like sour cream, lemon juice,

or buttermilk. On the other hand, baking powder has its own built in acid. Baking soda

increases browning and spreading, resulting in a flatter cookie. Baking powder will give a

puffier cookie.

Binding agents are the liquid in the recipe that hold the cookie together. Examples of binding

agents are eggs, milk, honey, and fruit juice. Cookies with more eggs will rise more and

spread less.

Salt, Spices, Flavorings, and Extracts / additives Salt is used to bring out flavor of many

foods, including sweet cookies while Spices, flavorings, and extracts add flavor to the

cookies. Usually these are added in small amounts.

2.6 Sensory quality attributes

Human accepts food on the basis of certain characteristics that he/she defines and perceives

with his/her senses. These attributes are described in terms of sensations and sometimes

referred as qualitative or sensory qualities. They include perception of appearance factors

such as color, size, shape and physical aspects; kinesthetic factors such as texture, viscosity,

consistency, finger feel and mouth feel; and flavor factors or sensations combining odor and

taste. Human judges are used to measure sensory characteristics of food. Sensory analysis is

too commonly often overlooked as a requirement before product launched. Similarly in this

research work sensory data such as appearance, color, smell, taste, texture aroma and mouth

feel are obtained through subjective evaluation by panelists.

Color and other aspects of appearance influence: Color is a quality factor that greatly

influences the appearance of a product. There are five functions that should be

considered in understanding human reactions to color in foods are (perception,

motivation, emotion, learning and thinking). The human eye has remarkably fine

qualitative discrimination for color, but it is not quantitative instrument. Appearance

refers to the size, shape together with defects and color are appearance factors that

32

greatly influence initial consumer impressions for this work the quality of the cookies

and tea –substitute in terms of shape, size, color, form and thickness.

Taste, aroma and flavor: Flavor as attribute of foods and beverages is defined as the

sum of the perceptions resulting from stimulation of the sense ends that are grouped

together at the entrance of the alimentary and respiratory tract. When food is consumed,

the interaction of taste, odor and textural feeling provides overall sensation best defined

as Flavor. Flavor results from compounds that are divided in to two broad classes:

Those responsible for taste and those responsible for odors, the later often designated as

aroma which provides both sensation. In simple term taste is the sensation perceived

when a small portion of cookies/ tea-substitute is taken by mouth in terms of saltiness,

sweetness, bitterness, and sourness caused by soluble substances in the mouth.

Texture as property of foodstuff apprehended both by the eye and muscle senses in the

mouth embracing roughness, smoothness, chew ability, stickiness, and so forth.

Overall acceptability is the sum of all the quality parameters and liking and disliking of

the products sensed by the consumer.

2.7 Concluding remarks

This chapter demonstrates byproducts from wheat milling industries (wheat germ and wheat

bran) could be used as a means of resource for production of cookies and tea substitutes.

According to data found from FAO and CSA, wheat production in Ethiopia is mounting.

Hence wheat production in 1997(<1,000,000 tons) till last year and become 4,039,113 tons in

2013 though the growth of production was not monotonous as can be seen in the figure.

Figure 2.6 Wheat production trend in Ethiopia.

Source: Graph developed on data of CSA and FAO (1997-2013)Moreover; according to

USDA foreign agricultural service report, 2013; in 2012, there were around 216 large flour

0

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

pro

du

cti

on

(to

ns)

33

mills in Ethiopia with a total of 4.2 million tons of milling capacity of flour per year; which is

expected to increase in number by now. The wheat consumption trend in Ethiopia is

gradually increasing in urban areas due to high population growth (about 2.6 percent a year),

migration of people to urban areas, and changes in life styles. Amount of byproducts from

milling industries is about (25-35) %; which can result more than 11 million quintals of

byproducts per year. The above facts show byproducts of wheat milling industries can be

used as means of resource without short supply throughout a year.

Milling industries in developed countries; use a source of enrichment for the final refined

white flour either directly by adding mineral and vitamins to the last product or by using

different wheat byproduct flours as a source of enrichment. This is done because they are

fully aware of wheat flour alone is nutritionally incompetent for daily use. Hence, developing

countries like Ethiopia show more scarcity in wheat and deficient it’s better to use byproducts

for human use rather than as animal feed. In view of the fact that defatted wheat germ flour

can be used as a supplement for the newly developed cookie; due to its high quality nutrition

content in protein, fiber, minerals. Similarly, from the s tudies wheat bran showed higher

amount of antioxidant activity.

A conclusion from studies establishes basic ideas and possibilities, which can be favorable to

support the development of wheat milling industries to use their own byproducts as a

resource. Apart from utilizing byproducts as a resource, minimizing agricultural waste for

production of new products to human better usage is something.

34

CHAPTER THREE

Materials and Methods

3.1. Raw materials collection, transportation and storage

The basic raw material used to make a defatted wheat germ cookies and tea substitute were

wheat grain byproducts directly harvested from Hora’s land production. It was collected from

one of the modern Midroc’s company named Hora Food Complex found in Alemgena. Wheat

bran, white wheat flour refined/ extracted at 76% and wheat germ samples were obtained

separately during production from this company. Each flour samples that were taken

carefully from the appropriate pipes were kept with a zipped, high-quality hygienic food

grade polypropylene plastic bags at room temperature where as the germ and bran kept in ice

box during transportation and stayed in freezer (0–5 oC) till laboratory analysis done. Carbon

dioxide was purchased from Moha Soft Drinks Industry, Gotera.

Analytical grade chemicals and reagents; 2, 2-diphenyl-1-picrylhydrazyl (DPPH), Folin

Ciocalteau reagent were purchased from Sigma-Aldrich Co. (St. Louis, Missouri, U.S.A).

Methanol, filter paper, safety equipments, vitamin C, sodium carbonate was bought from

Wise PLC. Other ingredients such as salt, sugar, aluminum and plastics-bags with seal,

baking powder, egg, butter, vanilla, oil and spices were obtained from well trusted markets

like Shoa and Abadir super market.

A) Wheat grain B) Wheat germ C) Wheat bran

Figure 3.1 Wheat grain and its byproducts (from Hora Complex PLC.).

35

3.2 Frame work of the research experiment

Figure 3.2 Frame work of the research experiment.

Defatted wheat germ

flour

Flours from wheat

milling Industries

Wheat bran Wheat flour Wheat germ

Proximate composition Analysis Extraction using

methanol

Defatting Wheat

germ flour process

by SFE

Farinogram Analysis and

Functional property analysis

(OAC, WAC, BD)

Blending flours

(WF & DWGF)

Determining total

phenolic content by Folin-

Ciocalteau assay and

antioxidant by DPPH

Tea substitute

WF BR1 BR2 BR3

- Mixing

- Kneading

- Cutting

- Baking

- Cooling

- Packing

Cookies

Produced

Sensory

quality

evaluation

Proximate composition

Analysis

Analysis of physical properties

(diameter, height, and weight)

36

3.3 Methods of processing

3.3.1 Preparation of defatted wheat germ flour

Raw wheat germ carefully selected and cleaned to remove contaminants. According to the

method described by Zhu and Zhou, (2005), the enzymes in the raw wheat germ were

inactivated by heating for 30 minutes at 105°C. Wheat germ samples were loaded into the

extraction vessel carbon dioxide from a cylinder was passed through a chiller kept at 2°C and

pumped into the extractor by a high pressure pump.

Raw wheat germ was defatted by using supercritical fluid extractor machine that is found in

AAiT’s Laboratory. According to methods by Alessandra et. al, 2009 and Shao and LiYa,

2011 the machine operated to defat wheat germ at pressure of 300 bar; temperature of 40°C;

CO2 flow rate of 20kg/h. Then the defatted wheat germ flour milled by coffee machine the

flour passed through a 250µm sieve diameter. Finally the flour stored in freezer (0-40C); after

extraction, the oil was collected separators while water and volatile components were

recovered. The extracted oil obtained was together with iced form water separated using

separatory funnel. The oil collected looks like as shown below:

(a) (b)

Figure 3.3 Oil obtained by defatting wheat germ flour (WGF) by supercritical fluid extractor

(SFE) before and after separation by using separatory funnel.

(a) Before separation by separatory funnel (b) after separation by separatory funnel

The extracted oil from the wheat germ is not pure oil form instead (icy form) latter melted in

to water and the oils float above. Separatory funnel is used in order to separate the oil from

the water part as shown in figure.

37

Figure 3.4 Simplified diagram for Preparation of DWGF.

3.3.2 Blend formulation and cookies production

Blend formulation

The basis for blend formulation of blended flour was done by taking into consideration some

important facts about the characteristics of DWGF results obtained after making farinograph

analysis and based on previous studies. The choice of these blend ratios were based on

studies of Muhammad, 2006 and Sahar, 2012 modified by using result obtained from

farinograph. That blends of wheat flour and DFWG flours containing 0%, 10%, 15%, and

20% DFWG flour, on a replacement basis, were taken. After blending, the mixture was

packed in poly propylene plastic bags and stored at room temperature till further analysis is

done.

10%DWGF 15% DWGF 20%DWGF

Raw wheat

germ

SFE operated at T=40 oC &

P= 300 Barr

Oil

Stored at

Freezer

(1-50C)

DWGF

Heating at

T= 1050C

Milling

Sieving

38

100% DWGF Control (100%Wheat flour)

Figure 3.5 Blended flours, defatted wheat germ flour and control flour.

Table 3.1 Percentage composition of blended flour for cookies

Flour blend Wheat flour (%) DWGF (%)

BR-0/control/WF 100 -

BR-1 90 10

BR-2 85 15

BR-3 80 20

Cookies production

Cookies were prepared according to the procedure described by (Taha et al., 2006) with some

modifications on type and amount of spices added. The basic ingredients used were 110 g of

flour blend, 29g shortening, 34 g of sugar, 13 g of beaten whole egg, and 1.1 g of baking

powder, 1.5 g of salt, 1.2 g vanilla, 2 g cinnamon, 1g clove, 0.6 g ginger and 5.3gm water.

First, dry ingredients were weighed and mixed thoroughly in a bowl by hand for 3–5 min.

The shortening, sugar and egg creamed together was added to the mixed dry ingredients and

rubbed in until uniform. The dough was sheeted using Lasagna sheeting machine with a

uniform thickness (5 mm) and cut out using a round cutter of diameter 45mm. The cut out

dough pieces were baked on lightly greased pans at baking temperatures 150, 180 and 210 oC

for 10-12 minutes in a baking oven. The prepared cookies were cooled to room temperature

and packed in polyethylene bags.

39

3.4 Methods of analysis

3.4.1 Analysis of proximate composition

Proximate chemical composition analysis such as moisture content, total ash, crude protein,

crude fat, and crude fiber of raw materials and finished products were carried out according

to AOAC (2000) official methods 925.09, 923.03, 920.87, 450.1 and 962.09 respectively.

Determination of moisture content

Moisture content was determined according to AOAC, (2000) using the official method

(925.09). Empty dishes and their lids (made of porcelain) was dried using drying oven for 1

hour at 100oC and cooled for 30 minute in the desiccators (with granular silica gel). A clean

dried and covered dish was weighed and about 5gm of the sample was transferred to the dish

(W1). The dish then placed in the oven at 100oC for 5hrs and cooled in desiccators and re-

weighed (W2). Then, the moisture content on wet basis estimated by the formula:

Moisture content in percent (%) =

Eq. (3.1)

Where: W1 = weight of fresh sample (g), W2 = weight of dry sample (g)

Determination of total ash

The ash content was determined by using AOAC, (2000) the official method (923.03). About

2.5g of sample was added into each dish. The dishes were placed on a hot plate under a fume-

hood and the temperature was slowly increased until smoking ceases and the samples become

thoroughly charred. The dishes (crucibles) were placed inside the muffle furnace at 550oC for

6 hr, and removed from the muffle and then placed in desiccators for 1hr to cool. Finally

weight of total ash was calculated by difference and expressed as percentage using the

formula:

Total Ash (%) =

Eq. (3.2)

Where: W1 = Weight in grams of the crucible with the sample

W2 = Weight in grams of the crucible plus ash

W = Weight in grams of empty crucible

Determination of crude protein

Crude protein was determined by Kjeldahl method according to (AOAC, 2000) using the

official method (920.87). About 1.0 gm of fresh samples were taken in a Tecator tube and

6ml of acid mixture (5parts of concentrated orthophosphric acid and 100 parts of

40

concentrated sulfuric acid) was added, mixed, thoroughly and 3.5ml of 30% hydrogen

peroxide was added step by step. As soon as the violent reaction had ceased, the tubes were

shaken for a few minutes and placed back into the rack. A 3.00g of the catalyst mixture

(ground 0.5g of selenium metal with 100g of potassium sulfate) was added into each tube,

and allowed to stand for about 10min. before digestion. When the temperature of the digester

reached 370oC, the tubes were lowered into the digester. The digestion was continued until a

clear solution was obtained for about 1h. The tubes in the rack was transferred into the fume

hood for cooling, 15ml of deionized water was added, and shaken to avoid precipitation of

sulfate in the solution.

Then, 250ml conical flask containing 25ml of the boric acid-indictor solution was placed

under the condenser of the distiller with its tips immersed into the solution. The digested and

diluted solution was transferred into the sample compartment of the distiller. The tubes were

rinsed with two portions of about 5ml de- ionized water and the rinses were added into the

solution. A 25ml of 40% sodium hydroxide solution was added into the compartment and

washed with a small amount of water, stopped and the steam switched on. About 100ml

solution of the sample was distilled, and then the receiver was lowered so that the tip of the

condenser is above the surface of the distiller. The distillation was continued until a total

volume of 150ml is collected. The tip was rinsed with a few milliliter of water before the

receiver was removed. Finally, the distillate is titrated with standardized 0.1N sulphuric acid

to a reddish color. The percent total nitrogen and crude protein were calculated us ing

equation (3.3).

Nitrogen (%) =

Eq. (3.3)

Where: N = Normality of standard sulfuric acid (0.1N).

T = Volume in ml of standard sulfuric acid solution used in the titration for the test material.

B = Volume in ml of standard sulfuric acid solution used in the titration for the blank

determination.

W = sample weight on dry matter basis and 14.007 is the molecular weight of nitrogen.

Crude protein content percent per weight = Total Nitrogen * universal conversion factor

N.B: The % of nitrogen is converted to % of protein by using appropriate conversion factor

i.e., (6.25 for biscuits, 6.31 for bran and 5.7 used for flour) according to Jones, (1941).

41

Determination of crude fat

Crude fat was determined based on the Sohxlet extraction method of AOAC (2000) using

official method 920.39. A 250 ml quick fit round bottom flask was washed and dried in an

oven (Gallenkamp, model OV 880, England) at 105°C for 25 minutes and allowed to cool to

room temperature before it was weighed. A clean and dried muslin thimble containing about

5 g of dried sample and covered with fat free cotton at the bottom and top was placed in the

extraction chamber. 2.0g of the samples were weighed into the thimble. This was inserted

into the extraction column with the condenser connected. 200ml of the extracting solvent

(petroleum ether, boiling point 40-60°C) was poured into the round bottom flask and fitted

into the extraction unit. The flask was then heated with the aid of electro-thermal heater at

60°C for 8 hrs.

Losses of solvent due to heating were checked with the aid of the condenser so that it cooled

and refluxed the evaporated solvent. After extraction, the thimble was removed and the

solvent salvaged by distillation. The flask containing the fat and residual solvent was placed

on a water bath to evaporate the solvent followed by a further drying in an oven

(Gallenkamp, model: OV 880, England, 1974) at 105°C for 30 minutes to completely

evaporate the solvent. It was then cooled in desiccators and weighed. The flask containing the

extracted fat was dried on a steam bath at 98ºC to a constant mass. The fat obtained was

expressed as a percentage of the initial weight of the sample using the formula.

Crude fat, % by weight =

Eq. (3.4)

Where: W1 = weight of the extraction flask (g),

W2= weight of extraction flask plus the dried crude fat (g), and

W= weight of samples (g)

Determination of crude fiber

Crude fiber was conducted using the method of AOAC, (2000) official method (962.09).

About 1.6g of fresh sample was placed into a 600ml beaker, 200ml of 1.25% sulfuric acid

was added, and boiled gently exactly for 30 minutes placing a watch glass over the mouth of

the beaker. During boiling, the level of the sample solution was kept constant with hot

distilled water. After 30 minute boiling, 20ml of 28% KOH was added and boiled gently for

further 30 minute, with occasional stirring. The solution was poured from beaker into sintered

glass crucible and then the vacuum pump was turned on. The wall of the beaker was rinsed

42

with hot distilled water several times; washing were transferred to crucible, and filtered. The

residue in the crucible was first washed with hot distilled water and filtered and then it was

washed with 1% H2SO4 and filtered. Secondly the residue was washed with hot distilled

water and filtered; and again washed with 1% NaOH and filtered. Finally the residue was

washed with water- free acetone. The crucible with its content dried for 2 hr in an electric

drying oven at 130 0C and cooled for 30 min in the desiccators (with granular silica gel), and

then weighed. The crucible was transferred to a small muffle furnace and incinerated for 30

min at 5500C. The crucible was cooled in the desiccators and weighed.

) =

Eq. (3.5)

Where: W1 = dried weight of crucible

W2 = Weight of crucible after ashing

W3 = dried weight of sample

M = % moisture of the sample

Determination of total carbohydrates

Total carbohydrates of the samples including crude fiber were determined by subtraction:

(3.6)

Energy calculation (kcal/100gm)

Energy content was obtained by multiplying the mean values of crude protein, crude fat and

total carbohydrate by the Atwater factors of 3.91, 9, 4.12 respectively, taking the sum of the

products and expressing the result in kilocalories per 100 g sample as reported by Edem et

al., (1990) and Onyeike et al., (1995). The formula for calculating energy is shown below.

Eq. (3.7)

Minerals analysis

Calcium and Magnesium

Calcium and Magnesium were determined using AOAC (1998) official method (985.35).

They were quantifying by atomic absorption spectrophotometric method. About 25 ml

composite aliquot was placed in previously cleaned evaporating dish. Then the aliquot was

dried in oven at 1000C for overnight. After completion of drying it was heated on hot plate

until smoking cease. Next the dish was placed in furnace at 5250C to obtain ash of white and

free from carbon for 4 hrs. Then dish was removed from the furnace and cooled. Following

this H2O and 2ml of HNO3 was added, dried on hot plate and the dish was returned to 5250c

43

furnace for 2hrs. After that the ash was dissolved in 5ml 1N HNO 3 and warmed on steam bath

for 3 min to aid in solution. Next add solution to 50ml volumetric flask with 1 N HNO3 and

repeated with 2 additional portion of 1N HNO3. Lanthanum Chloride (LaCl) solution was

added to final dilution of each standard then solution was tested to make 0.1% (W/V) La.

Blanks were prepared to represent all reagents and glassware. Then calibration curve was

prepared (concentration Vs absorbance) to determine each mineral using wave length and

flame specified in the table. Finally determine concentration of each mineral from its

calibration curve, and calculate the values using the following relation:

Eq. (3.8)

Where: W = Weight of the sample (g), V = Volume of the extract (ml), A = Concentration

(µg/ml) of sample solution and B = Concentration (µg/ml) of blank solution

Phosphorous determination

Phosphorous was determined by the colorimetric method using ammonium molybdate

(AOAC, 1984) using the official method (965.17). It was converted to phosphomolybdate,

which was reduced to a blue molybdenum compound. A sample solution was obtained from

mineral analysis. About 1 ml of the clear extract was taken from the sample solution and

diluted to 100ml with deionized water in a 100 ml volumetric flask. A 5ml (duiplicate) of the

sample dilution was added into test tubes. A 0.5 ml of molybdate and a 0.2ml

aminonaphthosulphonic acid was added into the test tube (sample solution) and mixed

thoroughly step by step. A 0.2 ml amino naphtholsulphonic acid was added into the test tube

repeatedly each time until the solution become clear. The solution was allowed to stand for

10min. The absorbance (reading A) of the solution was measured at 660 nm against distilled

water. Simultaneously with sample phosphorous, standard and blank analysis were carried

out. Standard and blank solutions were prepared as above but 5ml of working standard

(reading As) and 5ml of de- ionized water (reading AB) in place of the sample dilution were

used respectively. A standard curve was made from absorbance versus concentration and the

slope was used for calculation. First AB subtracted from all other readings

Eq. (3.9)

Where: A = reading of the sample solution; AB = reading of the blank solution; WF = weight

of fresh sample.

44

Potassium

Potassium was determined using AOAC (1998) official method (969.03) by using flame

absorption photometric. About 4 g sample was added into crucible and char on over flame.

Then it was placed in cold furnace at temperature of 525 oC and ashed for 2 hrs. Then 15 ml

of dilute HNO3 was added to crucible and it was filtered into 100 ml volumetric flask

through acid- washed quantitative paper. Then residue was washed with H2O. Next it was

diluted for direct readout as follows: about 1 ml aliquot was placed in 25 ml volumetric flask

and dilute to volume with H2O. At the same time blank solution was prepared by diluting 2

ml HNO3 to 100 ml with H2O. Finally read the blank, standards, and samples at 767 nm until

results were reproduced; record % T or absorption for each and Convert % absorption to

absorbance (A). At last standard curve was plotted A against concentration. Finally read

unknown concentrations from the curve and determine the values by the following relation:

Eq. (3.10)

Determination of rheology property of flours

A 300g of each blended and control flours were prepared and placed into the corresponding

farinograph mixing bowl. Water from a burette was added to the flour and mixed to form

dough. As the dough was mixed, the farinograph recorded a curve on graph. The amount of

water added (absorption) affects the position of the curve on the graph paper. Less water

increases dough consistency and moves the curve upward. The curve is centered on the 500-

Brabender unit (BU) line ±20 BU by adding the appropriate amount of water and is run until

the curve leaves the 500-BU line.

Functional properties of flour

Water and oil absorption capacity

Water and oil absorption capacity of flour was determined with the method reported by

Anderson et al.,(1969) as cited by Sukhcharn et al., (2008). Five gram flour of each sample

was weighed into a centrifuge tube and 30 ml of distilled water or oil was then added and

mixed thoroughly. This was allowed to stand for 30 min and centrifuged at 3,000 rpm for 15

min. The supernatant was then decanted and the sample weighed again. The amount of water

or oil retained in the sample was recorded as weight gain and was taken as water or oil

absorbed. The results were expressed as weight of water absorbed in grams per gram dry

matter of the sample.

Bulk density

45

The bulk density of the composite flour was analyzed according to the method stated by

Oladele and Aina (2007) in which a mass of 50 g of the sample was put in to a 100 ml

measuring cylinder. The cylinder was tapped continuously until a cons tant volume was

obtained. The bulk density was then calculated as weight of the grounded flour (g) divided by

its volume (ml).

Determination of physical properties of cookies

For the determination of diameter (width), thickness and spread factor, AACC (1995)

methods were followed.

Diameter

To determine the diameter (D), six cookies were placed edge to edge. The total diameter of

the six cookies was measured in cm by using a ruler. The cookies were rotated at an angle of

90 for duplicate reading. This was repeated once more and average diameter was taken in

centimeter.

Thickness

To determine the thickness (height), six cookies were placed on top of one another. The total

height was measured in millimeters with the help of ruler. This process was repeated twice to

get an average value and results were taken in mm.

Spread ratio

Spread ratio was determined by dividing the diameter to height of cookies.

3.5 Analysis of antioxidant activity and total phenolics

3.5.1 Sample extraction

Method used by (David, 2006, Bushra et al., 2009 and Barinderjit et al., 2012) with some

modification used for extraction. Ten grams of grounded fine bran weighed using an

aluminum foil and transferred in to a beaker. 40 ml methanol was added in a beaker. The

beakers were capped, placed in water bath at (40, 60 and 80 0C) for 20 min and were shaken

twice, while it’s inside the water bath. Finally, incubator shaker used to extract effectively.

Then the solvent layer from each test tube was separated by centrifugation at 5000rpm for 14

min. The residue was then extracted with two additional 20 ml portions of solvent as

described above. And the re-dissolved sample by the respective solvents used then passed

through what man No. 4 paper. The combined extracts were put below 50 0C in thermostat

oven. The separated solvent supernatant with the bioactive compounds in it was transferred to

clean, previously weighed and labeled test tube. Beaker cleansed, dried, weighted and made

46

ready. Weight differences were calculated for each samples resulted as shown below. All

samples were placed in refrigerator prior to testing.

Figure 3.6: Extraction method for antioxidant activities and phenolics analysis.

3.5.2 Determination of total phenolic content

Phenolic compounds concentration of methanolic extracts was estimated by using slightly

modified procedure by (Singleton and Rossi, 1965) as illustrated below. After extraction of

the bioactive chemicals, a stock solution of 10mg/ml extract in methanol (10:1) prepared.

10gm measured

using Al foil

added to beaker

40 ml methanol

added

Cupped and placed in

water bath at T= 40, 60 and

80oC for t=20 min.

Vortex the test tube 2X during

incubation

Centrifuged with ω=2000rpm,

t= 15 min.

200

Residue Mixed with

V=20 ml of Methanol,

and Vortexed

Solvent supernatant

transferred in clean,

weighted and labeled test

tube using Watman filter

paper

Centrifuged

evaporator/ oven at

T≤ 50 oC to remove

solvent

Solvent supernatant

Weighted to measure the

yield of sample (mass of

dry extract= by mass

difference)

Prepare stock solution and place

in refrigerator prior to use

Testing for determination TPC and DPPH

Incubator Shaker

Grounded

wheat bran

47

Then 1ml stock solution taken and diluted by 1ml methanol to have 2ml total volume, but the

concentration is diluted by half i.e. 5mg/ml. 1ml of Folin-Ciocalteu and 1ml of 7% of sodium

carborbonate added. The samples were vortexed for 3 min before sodium carbonate added.

Finally, 7ml water added to the sample then vortexed for the last time before absorption read.

Incubated for 90 minutes and spectrophotometer read at an absorbance of 725nm model

(Perkin Elmer Lamda 950 UV/Vis/NIR). First Gallic acid calibration curve standard is

required, so absorption for the gallic acid done in place of extract till R2 ≥0.98 achieved. All

phenolic compounds carried out in triplicate. Total phenolic content was expressed as mg

gallic acid equivalents (GAE)/100g weight. The total content of phenolics in wheat bran

extracts in gallic acid equivalent was calculated by the following formula:

Eq. (3.11)

Where TPC is the total content of phenolic compounds, mg/g fresh material, in GAE; C is the

concentration of gallic acid established from the calibration curve (Absorbance = 0.0134

gallic acid /g – 0.0144, R2 = 0.9918); V the volume of extract (L); m is the weight of extract

the concentration of gallic acid established from the calibration curve.

3.5.3 Determination of free radical scavenging activity

The effect of methanolic extracts on the DPPH radical was estimated according to Kirby and

Schmidt (1997). A 0.004% solution of DPPH radical solution in methanol was prepared and

then 4 ml of this solution was mixed with 1 ml of various concentrations (2– 14 mg/ml) of the

extracts in methanol. Finally, the samples were incubated for 30 min in the dark at room

temperature. Scavenging capacity was read spectrophotometrically model (Perkin Elmer

Lamda 950 UV/Vis/NIR) by monitoring the decrease in absorbance at 517 nm. The

maximum absorption was first verified by scanning freshly prepared DPPH from 200 to 800

nm using the scan mode of the spectrophotometer. Ascorbic acid was used as a standard and

mixture without extract was used as the control. Inhibition of free radical DPPH in percent

(I%) was then calculated:

Eq. (3.12)

Where A0 is the absorbance of the control and A1 is the absorbance of the sample.

3.6 Sensory quality evaluation

The sensory quality evaluation for coded samples (cookies and tea substitutes) done by using

descriptive sensory analysis via ten trained panelists. It was conducted in Addis Ababa

48

institute of Technology (AAiT) and in quiet, daylight, room temperature separated house at

different sessions. Descriptive tests can be qualitative or quantitative and involve detection

and description of both qualitative and quantitative sensory attributes. This has successfully

been used to obtain detailed descriptions of sensory attributes like aroma, flavor, texture and

others attributes of the cookies and tea substitute. Samples were evaluated for a number of

attributes by trained panelists (Lea et al.1998). Factors like health status, allergies,

availability, personality, verbal creativity, concentration, motivation, smoker, sensitivity,

medications were considered when selecting sensory panelists.

For ease of evaluation, the panelists were handed a scored sheets with 9-point hedonic scale

(a balanced bipolar scale around neutral at the center with four positive and four negative

categories on each side). The categories are labeled with phrases representing various degrees

of affect and those labels are arranged successively to suggest a single continuum of likes and

dislikes (Peryam & Pilgrim, 1957). The panelists were instructed to rate the products using a

9 point hedonic scale with 1 = dislike extremely, 5 = neither like nor dislike, 9 = like

extremely was used for attributes according to Amerine et al., (1965); Then coded samples of

cookies and tea substitute were presented to panelists together with water for mouth wash

within each taste interval.

3.7 Experimental design and statistical data analysis

The data obtained from each experiment were analyzed by using JMP statis tical analysis

software version 7.0; using complete randomized design (CRD). Significance was accepted at

0.05 level of probability (p<0.05). Mean separation was performed by “Each Pair Student’s t

test” for multiple comparisons of means. All of experiments were performed in triplicates and

duplicates. For defatted wheat germ enriched biscuits a factor of two; (Temperature and blend

ratio at level of three attained while for the tea substitute extraction Temperature). Data

analysis output of some properties and proximate compositions were listed in result and

discussion. The effect of replacing wheat flour by DWGF on the acceptability of the product

developed was evaluated by comparing them to a control and measuring the least significant

difference (LSD) at 5% according to method described by Mc Clave et al (1991). For wheat

bran sample analysis, average value was taken using Excel, 2007.

49

CHAPTER FOUR

Results and Discussion

4.1 Proximate chemical composition

Proximate chemical composition for raw materials including wheat germ, defatted wheat

germ, wheat flour, wheat bran and cookies were performed.

Proximate chemical composition of raw materials

Proximate analysis is crucial as one part of quality parameter starting from raw material

processing throughout the development process up to final state of product obtained in almost

every food product development, production/ process/. The proximate composition of foods

is used to determine the functional property, amount of nutrition value, and over all

acceptability of the final food product.

Proximate composition analysis was made for flours and cookies, which was made from

different blend ratio of composite flours and baking temperature. It offers vital clues about

the overall composition and nutritional status intended for edibility purpose. The results of

proximate analysis of raw materials WF, WGF, DWGF, and WB flour used for making

cookies and preparation of a tea substitute respectively are presented in tables 4.1, 4.2 and

4.3.

Table 4.1 Proximate composition of flours

Proximate Composition

Flour Types

WF WGF DWGF Bran

Ash (%) 0.84±0.06c 3.90±0.11b 4.72±0.04a 4.8±0.18 a

Moisture (%) 11.92±.0.06c 12.08±0.03b 12.99±0.04a 10.38±0.06d

Crude Fat (%) 0.52±0.03b 9.91±0.03a 1.01±0.04b 3.25±0.13b

Crude Fiber (%) 0.45±0.07c 1.19±0.03b 5.18±0.08a 11.91±0.85a

Crude Protein (%) 9.33±0.26d 18.41±0.04b 28.12±0.32a 14.17±0.28c

Total Carbohydrates (%) 77.39±0.17a 54.51±0.18c 53.17±0.19c 67.43±.1.8b

Samples Minerals (mg/100 gm)

Mg P Ca K

WF

DWGF

35±0.14b

45.95±0.35a

192.35±0.64b

392±0.42a

27±0.42b

46.6±0.92a

171±0.28b

1044.9±0.14a

All a-c values are means of duplicate ± SD on dry weight basis Means followed by different superscript within the same row differ significantly (P < 0.05). Where WF is wheat flour; WGF is wheat germ flour and DWGF is defatted wheat germ flour.

50

From the table 4.1 above, in proximate evaluation of the three types of flours, DWGF has ash

(4.72%), crude fiber (5.18%) and crude protein (28.12%) has a huge difference from WGF

with ash (3.9%), crude fiber (1.19%) and crude protein (18.41%) and WF with ash (0.84%),

crude fiber (0.45%) and crude protein (9.33%). Similarly in Table 4.2 DWGF resulted having

considerable amount of minerals than that of WF; resulting WF has the lowest nutritional

content. Consequently from table 4.1 the total amount of minerals and proximate composition

obtained from DWGF is much higher than that of WF; thus DWGF can be used for

supplementation as substitute of WF for upgrading nutritional content of the flour and its

product.

The data obtained were in agreement with the findings of various investigators Sahar, (2012).

The variation in moisture content value may be caused by due effect of conditioning and

storage conditions. A better yield of protein, ash and fiber in DWGF might be due to wheat

germ by nature is most nutrient rich part of the kernel.

Brans of cereals have been used mainly as source of dietary fiber in cereal foods due to

physiological and metabolical effects. Both insoluble and soluble fibers have many positive

effects on health and can help prevent diseases.

4.2 Effect of blend ratio and baking temperature on proximate

composition of cookies

In developed countries, wheat flour is generally fortified with vitamins B1, B2, niacin, with

minerals: iron, calcium and folate. Vitamins A and D can also be added to flour (Fortification

basics, USAID). But in developing countries like Ethiopia mostly the final refined wheat

flour, is nutritionally deficient wheat flour is consumed without being fortified this might be

due to the cost needed to buy or import the required amount of minerals and vitamins to

enrich the last refined white flour. However it’s possible to utilize the byproduct wheat germ

to upgrade the nutritional content of white wheat flour with least cost as raw material. Effect

of both baking temperature and blend ratio on proximate of baked cookies discussed below.

4.2.1 Effect of blend ratio and baking temperature on moisture content

As it can be observed from table 4.2 the moisture content of the cookies was significantly

affected by blend ratio, baking temperature, and their interaction (p< 0.05). The moisture

content has a unit of g/100g. With rising baking temperature the moisture content of cookies

becomes smaller this makes the biscuits to turn out to be crispier if kept for the average time

required. Similarly, as the amount of blend ratio used for baking the cookies increased down

51

the column the amount of moisture content increased. This is caused by the greater number of

hydroxyl existed inside the fiber structure that allow more water interaction through hydrogen

bonding. Similar findings were obtained by Piergiovanni & Farris (2008) and Manoela et al.,

(2006). Hence an excellence cookie is baked when the cookies resulted crispier than hard to

be chewed besides the amounts of water inside cookies indirectly measure the shelf life.

Table 2: Effect of blend ratio and baking temperature on proximate

% Moisture %protein %fiber %Ash

BWFT1 7.14 ± 0.04c 9.85±0.04

d* 1.84±0.04

c** 0.81±0.06

C***

BWFT2 7.08 ± 0.04d 9.35±0.08

d* 1.79±0.06

d** 0.79±0.09

c***

BWFT3 7.01 ± 0.04b 9.17±0.06

d* 1.71±0.05

d** 0.74±0.04

c***

BR1T1 7.52 ± 0.04b 13.83±0.09

c* 2.23±0.08

b** 1.28±0.03

b***

BR1T2 7.28 ± 0.05c 13.35±0.10

c* 2.17±0.08

c** 1.24±0.06

b***

BR1T3 6.87 ± 0.07b 12.87±0.06

c* 2.08±0.10

c** 1.19±0.11

b***

BR2T1 7.64 ± 0.04a 14.43±0.06

b* 2.93±0.13

a** 1.38±0.05

b***

BR2T2 7.49 ± 0.05b 14.29±0.08

b* 2.84±0.04

b** 1.31±0.06

ab***

BR2T3 6.99 ± 0.06b 14.19±0.04

b 2.77±0.07

b** 1.23±0.07

b***

BR3T1 7.69 ± 0.02a 15.88±0.18

a* 3.05±0.11

a** 1.55±0.06

a***

BR3T2 7.65 ± 0.06a 16.78±0.11

a* 3.10±0.04

a** 1.51±0.09

a***

BR3T3 7.47 ± 0.04a 15.08±0.12

a* 2.97±0.03

a** 1.47±0.07

a***

All a-d values are means of duplicate ± SD on dry weight basis Means followed by different superscript within the same row differ significantly (P < 0.05).

Where BWFT1= biscuit baked from wheat flour at T1 (150 oC), BWFT2= biscuit baked from wheat flour at T2 (180 oC), BWFT3= biscuit baked from wheat flour at T3 (210 oC), BR1T1= biscuit baked from (90% wheat flour and 10 % defatted wheat germ flour) at 150 oC,

BR1T2= biscuit baked from (90% wheat flour and 10 % defatted wheat germ flour) at 180 oC, BR1T3= biscuit baked from (90% wheat flour and 10 % defatted wheat germ flour) at

210 oC,BR2T1= biscuit baked from (85% wheat flour and 15 % defatted wheat germ flour) at 150 oC, BR2T2 =biscuit baked from (85% wheat flour and 15 % defatted wheat germ flour) at 180 oC, BR2T3= biscuit baked from (85% wheat flour and 15 % defatted wheat

germ flour) at 210 oC, BR3T1= biscuit baked from (80% wheat flour and 20 % defatted wheat germ flour) at 150 oC, BR3T2= biscuit baked from (80% wheat flour and 20%

defatted wheat germ flour) at 180 oC, BR3T3= biscuit baked from (80% wheat flour and 20% defatted wheat germ flour) at 210 oC.

4.2.2 Effect of blend ratio and baking temperature on crude protein content

Proteins also bind water on a molecular basis owing to hydrogen bonds within the solubilized

protein itself and therefore proteins also help to increase firmness of a product. Proteins in

defatted wheat germ enhance the flavor in finished products Horizon milling, (2013).

Baking temperature, blend ratio and their interaction affected the protein content of cookies.

The average protein content was declined slightly with increasing in baking temperature

along the row (not significant). This is either due to protein denaturation resulted due to the

effect of high temperature, or Maillard reaction, a reaction by free amino groups of amino

52

acids and sugars. Similar result found by Gulen and Eris (2004) when studied the effect of

heat stress on protein content.

As can be seen from table 4.2 the value of protein raised with every increment of blend ratio

down the column this is because the more amounts of amino acids are presence in each

increment in blend ratio. The amount of water associated to proteins is closely related with its

amino acids profile and increases with the number of charged residues, conformation,

hydrophobicity, pH, temperature, ionic strength and protein concentration Damodaran,

(1997).

4.2.3 Effect of blend ratio and baking temperature on crude fiber

Now a day a number of people in the world boost up consumption of dietary fiber intake by

accepting the fact it’s capable of reducing blood cholesterol levels, occurrence of colon

cancer even best for weight loss hence it is the indigestible part of foods, determined from the

residue remaining after extraction under specified conditions, it feels the belly full without

leaving the individual obsessed. According to (FAO, 2003) daily intake of dietary fiber is

25gm/day. Thus it’s advantageous to use the byproduct DWGF with almost no cost.

From table 4.2 baking temperature of the cookies doesn’t have that much significant effect

(P>0.05) on the crude fiber content of the cookies, however cookies were found significantly

affected by blend ratio (p<0.05). As the blend ratio of the composite flour used increased the

amount of crude fiber content also increased. Therefore supplementation of wheat flour with

defatted wheat germ flour could be one alternative to make our food prosperous nutritionally.

Similar findings were obtained by (Mian et al., 2009).

4.2.4 Effect of blend ratio and baking temperature on ash

Ash is mineral content of foods, determined by combustion of the sample under defined

conditions and weighing of the residue. The ash content of the cookie was found significantly

influenced by the blend ratio (p< 0.05) but not by baking temperature and their interaction.

Increasing in the blend ratio of DWGF in the respective blend ratios similarly increased the

amount of ash in the last product. This could be the result of higher amount of ash content in

defatted wheat germ flour than wheat flour initially. Ash was found not significantly

influenced by baking temperature (p > 0.05) similar finding with Biniyam, (2010).

53

Table 3: Mineral composition of biscuits at different blend proportions

Flours Minerals

Mg P Ca K

WF 25.65±1.34d 179.15±1.20d 39.55±1.06a 130.1±0.85d

BBR1 46.2±0.98c 207.85±0.35c 40.4±0.28a 213.8±0.42c

BBR2 54.5±0.84b 216.7±0.57b 40.6±0.42a 235.0±0.28b

BBR3 61.95±1.34a 232.5±0.84a 41.1±0.28a 278.7±0.84a

All values are means of duplicate ± SD

Means followed by different superscript within the same column differ significantly (P < 0.05).

According to (Fenema, 1996) Mineral elements, unlike vitamins and amino acids, cannot be

destroyed by exposure to heat this could be the reason that baking temperature was not

influence ash and mineral content of the cookie significantly. Therefore amount of minerals

presented in the cookies is significantly affected (P<0.05) by blend ratio, this is basically true

hence the defatted wheat germ flour has got magnificent amount of minerals than that of the

control. Similar findings can be observed by (Mian et al., 2009).

4.3 Rheological property of flours

Rheology is the science that studies the flow and deformations of solids and fluids under the

influence of mechanical forces as a function of time. The rheological measures of a product

in the manufacture stage can be useful in quality control. The microstructure of a product can

also be correlated with its rheological behavior, allowing development of new materials

(Gipsy and Gustavo, 2004).

In the food industry, rheology provides a scientific basis for subjective measurements such as

mouth feel, spread ability and pour ability by using farinograph an instruments used to

investigate the physical properties of dough. Rheological properties such as elasticity,

viscosity and extensibility are important in the prediction of the processing parameters of

dough and quality of end product (Hruskova, 2001).

The measurements completed on the variation of the kneading torque by two different

modalities, using an electronic brabender farinograph and an experimental plant with torques.

Rheological properties of the different types of blends and the control were analyzed. Mixer

temperature was set at 30 oC prior for all tests.

54

Figure 4.1 Farinograph values of control flour/ WF.

Figure 4.2 Farinograph value for BR1.

4.3.1 Water absorption

It is the amount of water required to center the farinograph curve on the 500-Brabender unit

(BU) line. From this water absorption showed tendency of change in the physical

characteristics of the dough found from wheat flour alone and blended with defatted wheat

germ flour with the increase in the proportion of defatted wheat germ flour in the mixture.

55

The increase in absorption was mainly due to the increase in DWGF, which is higher in fiber

content which cause high number of hydroxyl groups existing in the fiber molecules,

responsible to allow more water interaction due hydrogen bonding similar findings with

Abdullatif, (2009). The higher the blend proportion, the higher the water absorption of the

flour, this might be due to the factor that affect flour water absorption are principally the flour

moisture content, its protein level, and the amount of damaged starch.

Figure 4.3 Farinograph result for BR2.

Figure 4.4 Farinograph value for BR3.

56

4.3.2 Dough development time

Among all the samples wheat flour (control) has got the lowest value and the blend with

higher proportion BR3 took highest time to be developed. This showed the addition of more

defatted wheat germ resulted higher amount of time the dough to be developed this again

basically due to increased amount of moisture content inside the water loving hydroxyl group

which are present highly in the fiber part this as a result ended up the final dough

development time to be higher as the more amount of defatted wheat germ blended. This

finding is in agreement with Abdellatif, (2009).

4.3.3 Dough stability

The control needed less dough stability time, whereas the blended ones desired more time of

stability. Though longer stability means easier handling for the baker and less possibility of

over mixing, the dough with an increase in defatted wheat germ flour ratio resulted having

difficulty to achieve stability with in short period of time as that of the control. This is mainly

due to excellent amount of protein content present inside the defatted wheat germ flour. And

this might be due the difference in protein content and quality of flours which is similar

finding with (Holas and Tipples, 1978 and (Sudha et al., 2011).

4.3.4 Farinograph quality number (FQN)

Wheat flour has got the lowest farinograph quality number while the blended ones have got

uppermost farinograph quality number. As the level of the defatted wheat germ flour added

increased the farinograph quality number to signifying that the flour had high water

absorption capacity same finding as (Toufeili et al., 1999). Hence higher farinograph quality

number obtained for higher amount of proportion in the blend.

4.4 Functional properties of flours

Functional properties are those parameters that determine the application and use of food

material for various food products. It is the characteristics of a substance that affect its

behavior and that of products to which it is added. Influence potential applications of a

substance in the food industry, as a particular functional property may be especially useful for

the manufacture and stability of specific types of foods. Include a wide range of

characteristics, such as water absorption capacity, bulk density, and oil absorption capacity.

The wheat flour and blend of DWGF analyzed for their functional properties for the

formulation of value added cookies. The mean values for bulk density, water and oil absorption

capacities were shown in Table 4.9.

57

4.4.1 Bulk density

Bulk density, weight per unit volume of wheat flour and the blended composites flours,

presented in table 4.9. The highest bulk density was obtained by BR3, BR2, BR1 and finally

WF. Having higher bulk density of composite flour exhibit better compactness and possible

mixed effect caused by the interaction of the molecules of the DWGF and WF. The higher

bulk density observed for the composite flour implies that a denser packaging material may

be required for this product. Bulk density gives information on the porosity of a product and

can influence the choice of package and its design (Odedeji and Oyeleke, 2010).

4.4.2 Water absorption capacity

The water absorption capacity is a function of water holding ability of the flour sample. From

the analysis reported in table 4.9. The highest WAC of DWGF could be attributed due the

presence of high protein, crude fiber and higher amounts of hydrophilic constituents in

DWGF. Similar findings were obtained by Adeyemi and Beckley (1986) reported that water

absorption capacities of flours correlate positively with the particle size of flours. Higher

WAC of the composite flour may be attributed to their higher protein contents. Afoakwa,

(1996), reported that proteins are mainly responsible for the bulk of water uptake in flours.

Water absorption capacity is a critical function of protein in various food products like soups,

gravies, doughs and baked products Sosulski et al., (1976).

4.4.3 Oil absorption capacity

Oil absorption capacity (OAC) is another vital functional property of flour hence it’s

excellent in enhancing the mouth feel while preserve the flavor of food products. The

removal of fat from the samples exposes the water binding sites on the side chain groups of

protein units previously blocked in a lipophilic environment thereby leading to an increase in

WAC value as in defatted flours as mentioned earlier. Similar observation has been reported

by Lin et al. (1974). Oil absorption increased in proportion to the protein contents of the

flour. The mechanism of fat binding is not fully understood, but formation of lipid-protein

complexes is markedly responsible for oil retention.

As can be seen from table 4.9 the oil absorption capacity of flours increased from wheat flour

through the blended ratios. The oil absorption of defatted wheat germ flour was higher than

those of wheat flour. This implied DWGF may have more hydrophobic proteins flour; the

more hydrophobic proteins demonstrate superior binding of lipids. Hence the major chemical

58

component affecting oil absorption capacity is protein, which is composed of both

hydrophilic and hydrophobic parts. This on the other hand shows DWGF with the higher

blend ratio improved mouth feel and preserve the flavor of the value added cookies produced

(Aremu et al., 2006).

Table 4: Functional properties of flours

Flours B.D WAC OAC

WF 0.625±.003 0.78±0.042 0.78±.04

BR1 0.65±.028 0.87±.042 0.95±.021

BR2 0.67±.008 1.07±0.049 1.19±.028

BR3 0.68±.014 1.98±0.049 2.14±.042

All values are means of duplicate ± standard deviations Where B.D = bulk density, WAC=water absorption capacity & OAC= oil absorption capacity

4.5 Physical properties of cookies

The physical properties of cookies are one crucial feature that determines the consumer

acceptability. Weights (gm), height (cm), diameter (cm) were measure and spread ratio was

calculated as the diameter to height ratio.

Table 5: Effect of blend ratio and baking temperature on physical properties of cookies

Weight diameter height Spread ratio

BWFT1 5.43±0.01d 4.52±0.07a 0.53±.001a 8.69±0.05a

BWFT2 5.37±.007d 4.40±0.04a 0.52±0.04a 8.63±0.08a

BWFT3 5.30±0.01c 4.39±0.06a 0.51±0.01a 8.61±0.07a

BR1T1 6.44±0.02c 3.88±0.10b 0.522±0.01b 7.46±0.05c

BR1T2 6.29±0.02c 3.850±0.08b 0.51±0.07b 7.54±0.04c

BR1T3 6.29±0.04b 3.840±0.04b 0.50±.004b 7.68±0.06bc

BR2T1 6.74±0.01b 3.76±0.06bc 0.49±.0014c 7.67±0.07b

BR2T2 6.52±0.02b 3.800±0.01b 0.51±0.02c 7.65±0.09c

BR2T3 6.42±0.01b 3.74±0.07bc 0.48±.001c 7.65±0.03c

BR3T1 7.06±0.04a 3.63±0.08c 0.48±.002d 7.72±0.07b

BR3T2 6.87±0.06a 3.610±0.05c 0.47±0.02d 7.85±0.06b

BR3T3 6.8±0.014a 3.610±0.09c 0.46±0.01d 7.84±0.08b

All values are means of duplicate ± standard deviations

Means followed by different superscript within the same column differ significantly (P < 0.05).

4.5.1 Effect of blend ratio and baking temperature on weight of cookies

The method of Zoulias et. al., (2002) used for measuring the physical properties weight,

diameter height and spread ratio of the value added cookies. And averages of the duplicate

59

measures of both blend ratio and baking temperature effect were analyzed. Physical analysis

of cookies used as an essential tool for both consumers and manufacturers, hence spread of

the biscuits should be according to specification. The effect of blend ratio and temperature

showed a significance difference in the weight of cookies. As the blend ratio of the cookie

increased the weight of the cookies also increased this could be majorly as a result of

imbitions of water due to the higher water absorption owing to high protein content in DWGF

or could be higher bulk density of DWGF in each proportion increment that is similar finding

with (Gernah et al., 2014). However, there is an adverse effect of temperature on weight loss

of the cookies this might be due to the up taken of high amount of moisture content in every

raise in temperature.

4.5.2 Effect of blend ratio and baking temperature on diameter of cookies

Effect of blend ratio on diameter has got a significant difference (P<0.05) of cookies. There

was decrement in diameter and height as the blend ratio increased this might be due to an

increment in fiber concentration in every blend formulation. The control cookie made of

wheat flour had wider diameter than supplemented cookie. Cookies made of BR3 were with

the smaller diameter mainly due to the presence of more fiber. A similar decreased in

diameter was also reported by Singh et al., (2008), and by Biniyam, (2009) wheat, quality

protein maize and carrot.

4.5.3 Effect of blend ratio and baking temperature on cookies height

The effects of blend ratio on height of the cookies were similar to that of the diameter.

As the supplementation of defatted wheat germ increased the height of the cookies resulted

decreased. This might be due to the different flour quality of the blended flours (presence of

high fiber) or the absence of ample amount of gluten inside the byproduct defatted wheat

germ flour. When there was a raise in temperature the height of the cookie showed slight

diminish this could be due to reduction by volume of cookies due high amount of moisture up

taken by the raise in temperature.

4.5.4 Effect of blend ratio and temperature on spread ratio

From the table above spread ratio decreased with an increase in blend ratio. Hence it’s an

indication of the viscous property of dough and influenced by the recipe, ingredients,

procedures and conditions used in biscuit production (Dogan, 1998). McWatters (1978)

reported that rapid partitioning of free water to hydrophilic sites during mixing increased

60

dough viscosity, thereby limiting cookie spread; or a decrease in spread factor and thickness

was due to the increase in amount of protein, as addition of soy flour which could attribute to

higher protein content of soy flour as reported by Mridula et. al., (2007). These results were

similar to those reported for cookies prepared from wheat–cowpea (McWatters et al., 2003)

and wheat–soybean (Shrestha & Noomhorm, 2002) flour blends. However, it has been

suggested that spread ratio is affected by the competition of ingredients for the available

water, by flour or any other ingredient, which absorbs water during dough mixing, will

decrease it (Fuhr, 1962).

4.6 Total phenolic content and antioxidant activity of bran

4.6.1Total phenolic content of wheat bran

In preliminary determination of total phenolic content of wheat bran, standard curve for the

gallic acid obtained by Excel, 2007 from table found in appendix III. Total phenolic content

(TPC) was expressed as milligrams of gallic acid equivalent per gram (mg/g) of dry extract

samples. Gallic acid, the major phenolic acid found in wheat, was used as a standard. Total

phenolic content of wheat bran using different temperature range differed (1.037, 2.15, 3.58

and 3.68) mg of GAE /g for temperatures 40, 80, and 60 oC using absolute and solvent

methanol for extraction. These results are in agreement with that observed by Vaher et al.

(2010) who found that the bran layers have the highest content of total phenolics content.

This may be due to the use of mixture alcohol and water present the advantage of depends

mainly on the hydroxyl groups, the molecular size and the length of hydrocarbon. The higher

total phenolic compounds were extracted by using organics solvent (alcohols) whose polarity

is modified with water. These mixtures become ideal and selective to extract a great number

of bioactive compounds of phenolic compounds. Whereas water given more amount of yield,

but only is not good to extract polyphenols. Water extracts only the water-soluble bioactive

compounds; moreover much other residual substances and impurities are present in the

aqueous extracts (Zohra, 2011).

Therefore for the experiment, with increase in solvent extraction temperature, there was

significant increase in total phenolic content in cereal brans. Maximum total phenolic

contents were obtained at 60°C (3.68mg GAE g- l) while minimum at 40°C (1.037 mg GAE

g-l). The difference in total phenolic content among each extraction may be due to the

difference in heat labile nature of cereal bran (Dar and Savita, 2011).

61

As can be seen from the result from the table on appendix III ; the effect of different

temperatures during extraction result higher amount of TPC at 60oC obtained 3.58 and

3.68mg/gm GAE using absolute and solvent methanol. According to Oufnac et al. (2007)

with rise in extraction temperature more phenolic compounds are released. Earlier research

has shown that higher temperature during extraction has a tendency to increase antioxidant

activity (Brand-Williams et al., 1995). Increased extraction temperature may breakdown or

increase hydrolysis of the bonds of some bound phenolic compounds and causes them to

become extractable phenolic compounds. Similar fact was observed by Sun et al., (2007),

while extracting total phenols from asparagus. And the aqueous methanol was better than the

absolute one may be due to the fact that phenolics are often extracted in higher amounts in

more polar solvents such as aqueous methanol as compared with absolute methanol similar

results were obtained by Anwar et al., 2007), Onyeneho and Hettiarachchy, (1992), Fulcher et

al., (1972) These results are in agreement with previous reports which also reported that

antioxidants including phenolics are concentrated in the aleurone fraction of bran.

4.6.2 Antioxidant activity of wheat bran

The DPPH method is common for determination of free radical scavenging activity of

antioxidant. DPPH (2, 2- diphenyl-1-picrylhydrazyl) hence it’s a very stable organic free

radical and presents the ability of accepting an electron or hydrogen radical. The capacity of

wheat extract to scavenge the stable DPPH radical is shown in figure 4.5 where blue, red and

green are percentage inhibition capacities for ascorbic acid, methanol solvent and absolute

methanol with IC50 value (1.43, 1.75, and 2.125) mg/ml respectively. IC50 determined as the

lowest concentration that will inhibit 50% of a process for ascorbic acid as control, followed

by extract by methanol solvent and absolute methanol respectively. This indicated extract by

solvent methanol has higher scavenging capacity than absolute methanol.

Similar findings found by Bushra, 2009 that extract yields and resulting antioxidant activities

of the plant materials are strongly dependent on the nature of extracting solvent, due to the

presence of different antioxidant compounds of varied chemical characteristics and polarities

that may or may not be soluble in a particular solvent. Polar solvents are frequently employed

for the recovery of polyphenols from a plant matrix. The most suitable of these solvents are

(hot or cold) aqueous mixtures containing methanol, ethanol, acetone and ethyl acetate, and

according to Liyangli, 2007each type of antioxidant compound is likely to exhibit different

free radical scavenging properties depending on the nature and mechanism of the free

62

radicals used and their reactivities with different antioxidant compounds, a moderately polar

extraction solvent such as 80% methanol may be more effective for extracting phenolic

antioxidants and DPPH scavengers from wheat grain than absolute methanol.

Figure 4.5 Free radical scavenging methanolic extract of wheat bran and control.

4.7 Sensory quality evaluation of products

The last evaluation conducted by the panelist was the overall acceptability of cookies. Hence

overall acceptability is the sum of all the quality parameters and loving the cookies,

considered as basic for new product development. The overall acceptability of the cookie was

influenced by both blend proportion and baking temperature. The uppermost score of

judgment on over all acceptability was observed for BR2 at 1800C while the least one was

BR3 at T1.

Figure 4.5 (a) Sensory evaluation for cookies

For the sensory evaluation cookies were selected primarily, followed by hedonic test. From

this the overall acceptability of BR2 was more acceptable than all the others included control

0

10

20

30

40

50

60

70

80

90

100

110

0 2 4 6 8 10 12

Ascorbic

Me-ol & H2O

Me-ol

0 2 4 6 8

10 WFBT2

WFBT1

WFBT3

BBR1T2

BBR1T1

BBR1T3

BBR2T2

BBR2T1

BBR2T3

BBR3T2

BBR3T1

BBR3T3 appea.

color

flavor

texture

taste

OAA

63

(WF). This might be due to the enhanced flavor and enriched texture for end product

imparted by the defatted wheat germ flour. This finding is not in agreement with (Sahar,

2012) this could be mainly due to culture difference and perception of acceptance.

For the sensory evaluation of tea substitute using a 9 point hedonic scale test, the flavored

ones showed a better sensory quality than that of unflavored one. Especially result of tea

substitute using additives funnel seed and cinnamon was exceptionally adored by the

pannalists.

0

2

4

6

8

10 Appeara.

Aroma

Taste Flavour

Overall A. a

b

c

d

Figure 4.5 (b) Sensory quality evaluations for tea substitute.

Where a= unflavored tea b= funneled tea c= mint tea d= cinnamon tea

64

CHAPTER FIVE

Process Technology

5.1 Production process for cookies and tea substitute

b) Tea-substitute

a) Cookie production

Figure 5.1 Flow chart diagram for developed products (a and b).

Drying

Wheat Bran

Cleaning

Heating

Milling

Flavoring

Packaging

Byproducts from Wheat

Milling Industries

Wheat Germ

Defatting

Blending

Kneading

Forming

Molding/Cutting

Baking

Cooling

Packaging

Cleaning

Enzyme inactivation

Wheat Flour

b) Tea substitute

65

5.2 Suggested cookies manufacturing plant

Figure 5.2 Equipment layouts for cookies production

1. Wheat germ pretreatment unit; 2. Supercritical fluid extractor-CO2; 2-1 SFE- vessel; 2-2 Expansion valve; 2-3 Collection vessel; 2-4 Gas pump;

3.Mill; 4.Sreening; 5.Blender; 6.Kneader; 7.Sheeter; 8.Cutter; 9.Baking oven; 10.Cooling; 11.End product evaluation; 12. Packing and distribution

67

CHAPTER SIX

Conclusions and Recommendations

6.1 Conclusions

This study was primarily and mainly aimed to investigate the possibility of exploit

underutilized byproducts (wheat germ and wheat bran) from wheat milling industries; with

the intention of developing value added products (cookies and tea substitute) respectively.

Secondly, it was attempted to determine appropriate blend ratio, temperature and their

combination plus their impact on the (functional, physical and rheological property of flours

(proximate and sensory quality)) of the newly formulated products; and tea substitute from

wheat bran demonstrated better antioxidant activity and phenolic content.

From the findings, when wheat flour supplemented with defatted wheat germ flour with

protein (28.12), fiber (5.18) was more than adequate to be used as enrichment of wheat flour

with protein (9.33), fiber (0.45) and much lesser amount of minerals (Mg, P, Ca, K) content

than that of the defatted wheat germ flour. Hence, the Farinogram analysis demonstrated

acceptable range of dough character existed till level of 15%. Finally, the 15% blended

cookies baked at temperature of 180oC result very good sensory acceptance, better nutritional

content (protein=16.8, fiber=3) quite not destructively affected by temperature and blend

ratio.

The wheat bran extracted using absolute and solvent methanol for determination of total

phenolic content using Folin-Ciocalteu assay and antioxidant activity using DPPH

scavenging assay at (40, 60 and 80) oC . Gallic acid and ascorbic acid were used as a control

for both assays respectively. A higher total phenolic content (3.68mg/gm) of gallic acid

equivalent was investigated at a temperature of 60oC using solvent methanol. Percentage

inhibition capacity for ascorbic acid, methanol solvent and absolute methanol with IC50 value

was (1.43, 1.75, and 2.125) mg/ml respectively. The tea substitute made from wheat bran

flavored with funnel seed and cinnamon resulted better sensory acceptance.

68

6.2 Recommendations

From the study result, partial substitution of wheat flour with defatted wheat germ flour for

cookies making appeared to promising in nutrition point of view; similarly the tea substitute

of variety additives were success too. The following recommendations are forwarded based

on holistic assessment of the subject area for production of value added products from

defatted wheat germ flour and wheat flour:

Establish benches mark for further research pertaining to work on the germ o il

production and characterization which is useful for making variety of products in

different sectors; hence it owes high amount of tocopherol and unsaturated fatty acids

both of which are of great importance in human metabolism and cannot be

synthesized by organism.

Hence defatted wheat germ flour resulted in much lesser amount of oil, which was

responsible for rancidity of the flour, long and durable researches should be done on

determination of shelf life of flour. It can be used as nutrient supplement for the

wheat flour alone which has smaller nutritional content; even more these by-products

from wheat milling industries sold in much lesser price so anyone could buy it cheap

and use it for home baking purpose; because this encourages the expansion of

existing and development of value added flour, and a new type of cookies from

inexpensive and available resources, besides it improves the health status of

malnutrition vulnerable group of the society

Further studies on defatted wheat germ flour based value added products like as a

source for production of meat products by partial replacement of the meat should

be done.

Further studies on wheat bran alone for determination of all other antioxidant

activities; and other value added products like soft drink in United Kingdom requires

further investigation.

69

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Appendices

Appendix I: Scorecard for the sensory quality evaluation using nine point hedonic scales

Nine Point Hedonic Scaling Scored-Card for Cookies

Date .........................................

Name....................................................... Instruction: Taste the coded cookies samples. Fill your appropriate scores which best

describes your feeling (according to the 9-point hedonic scale below). Please rinse your

palate by drinking water in between samples.

9. Point Hedonic Scaling

9. Like ext remely 6. Like slightly 3. Dislike moderately

8. Like very much 5. Neither like nor d islike 2. Dislike very much

7. Like moderately 4. Dislike slightly 1. Dislike ext remely

If you have additional Comments/suggestions please do not hesitate to jot down:

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

...................................................................................................

Thank you!

Sample

Code

Attributes

Appearance Color Flavor Texture Taste Overall accept.

BWFT1

BWFT2

BWFT3

BBR1T1

BBR1T2

BBR1T3

BBR2T1

BBR2T2

BBR2T3

BBR3T1

BBR3T2

BBR3T3

77

Appendix II

Score card for the sensory quality evaluation using nine point hedonic scales

Nine Point Hedonic Scaling Scored-Card for tea substitute

Date .........................................

Name.......................................................

Instruction: Taste the coded samples (a-d). Fill your appropriate scores which best describes

your feeling (according to the 9-point hedonic scale below). Please rinse your palate by

drinking water in between samples.

9. Point Hedonic Scaling

9. Like ext remely 6. Like slightly 3. Dislike moderately

8. Like very much 5. Neither like nor d islike 2. Dislike very much

7. Like moderately 4. Dislike slightly 1. Dislike ext remely

If you have additional Comments/suggestions please do not hesitate to jot down:

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

......................................................................................................................................................

...................................................................................................

Thank you!

Sample

Code

Attributes

Appearance Aroma Mouth

Feel

Flavor Overall

acceptability

A

B

C

D

78

Appendix III

Data obtained for bran extraction and tests

Standard Gallic acid absorption to produce standard curve

Absorbance read for TPC of extracted samples

Samples TPC Absorbance

Solvent methanol extracted at 60oC 3.68 0.1824

Run Test

tubes

GA

5mg/m

l

ME-o l

(µlt)

Vol.T

(ml)

FC

(ml)

Na2CO3

(ml)

DD Water

(ml)

Con.

(µg/ml)

Avg.

1 B11 0 100 µlt 0.1 1ml 1ml 7ml 0 0.07701

2 B12 0 100 0.1 1 1 7 0

3 B13 0 100 0.1 1 1 7 0

4 GA11 5 95 0.1 1 1 7 5 0..091

5 GA12 5 95 0.1 1 1 7 5

6 GA13 5 95 0.1 1 1 7 5

7 GA21 15 µlt 85 0.1 1 1 7 15 0.1182

8 GA22 15 µlt 85 0.1 1 1 7 15

9 G23 15 µlt 85 0.1 1 1 7 15

10 GA31 30 µlt 70 0.1 1 1 7 30 0.1609

11 GA32 30 µlt 70 0.1 1 1 7 30

12 GA33 30 µlt 70 0.1 1 1 7 30

13 GA41 50 µlt 50 0.1 1 1 7 50 0.2154

14 GA42 50 µlt 50 0.1 1 1 7 50

15 GA43 50 µlt 50 0.1 1 1 7 50

16 GA51 70 µlt 30 0.1 1 1 7 70 0.2668

17 GA52 70 µlt 30 0.1 1 1 7 70

18 GA53 70 µlt 30 0.1 1 1 7 70

19 GA61 100 µlt 0 0.1 1 1 7 100 0.368

20 GA62 100 µlt 0 0.1 1 1 7 100

21 GA63 100 µlt 0 0.1 1 1 7 100

79

Absolutemethanol extracted at 60oC 3.58 0.1793

Methanol extracted at 80 oC 2.15 0.1381

Methanol extracedt at 40 oC 1.037 0.10577

Scavenging capacity using DPPH for control and two samples

Standard Gallic acid curve (absorption Vs concentration)

Concentration (mg/ml)

Ascorbic

acid

Solvent

methanol

bsolute

Methanol

0

0 0 0

0.5

18.7 6.623 4.322

2

90 58.37 40.752

2.5

96 68.685 54.595

5

91.5 83 79.567

10

92 86.605 82.567