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Journal of Culinary Science & Technology

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Evaluation of Cocoyam-Wheat Composite Flour inPastry Products Based on Proximate Composition,Physicochemical, Functional, and SensoryProperties

P. T. Akonor, C. Tortoe & E. S. Buckman

To cite this article: P. T. Akonor, C. Tortoe & E. S. Buckman (2018) Evaluation of Cocoyam-Wheat Composite Flour in Pastry Products Based on Proximate Composition, Physicochemical,Functional, and Sensory Properties, Journal of Culinary Science & Technology, 16:1, 52-65, DOI:10.1080/15428052.2017.1333937

To link to this article: https://doi.org/10.1080/15428052.2017.1333937

Published online: 22 Jun 2017.

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Evaluation of Cocoyam-Wheat Composite Flour in PastryProducts Based on Proximate Composition,Physicochemical, Functional, and Sensory PropertiesP. T. Akonor, C. Tortoe, and E. S. Buckman

Food Technology Research Division, CSIR-Food Research Institute, Accra, Ghana

ABSTRACTThis study characterized the nutritional and functionalproperties of cocoyam flour and evaluated the sensoryproperties of model products made from cocoyam-wheatcomposite. Proximate composition of cocoyam flour, physi-cochemical, functional, and pasting properties of cocoyam-wheat composite blends were determined by standardmethods. Sensory evaluation of doughnuts, bread, andcookies was done by 50 panelists. Protein and ash contentof cocoyam flour were 8.5% and 2.4%, respectively,whereas fat was less than 1%. Increasing cocoyam floursignificantly increased (p < 0.05) water binding capacity,swelling power, and bulk density of composite blends.Peak viscosity of blends increased nearly two folds, whenthe proportion of cocoyam flour was increased from 5% to30%. Addition of cocoyam flour gave composite flour withhigh breakdown and setback viscosities. Sensory evaluationshowed that for cookies, up to 30% of wheat flour could bereplaced by cocoyam flour, whereas 20% is acceptable indoughnuts and bread.

ARTICLE HISTORYReceived 25 October 2016Accepted 19 May 2017

KEYWORDSCocoyam; composite flour;functional and sensoryproperties; pastry products

Introduction

New cocoyam or tannia (Xanthosoma sagittifolium) is a major staple in most partsof the tropics, even though it is less important compared to other root and tubercrops such as yam, cassava, and sweet potato (Opara, 2002). The corms andcormels of tannia are nutritious and contribute significant amounts of carbohy-drates to diets. They supply easily digestible starch and are known to contain goodamounts of protein and vitamins B and C, as well as significant amounts of dietaryfiber (Sefa-Dedeh & Sackey, 2004). Opoku-Agyemang, Bennett-Lartey, andMarkwei (2004) have noted that the cormels of Xanthosoma sagittifolium areboiled, baked, fried, roasted, pounded into fufu, or processed into flour.Consumption of the cocoyam in some local communities ismainly during seasonswhich precede the harvesting of yams. In 2014, production and per capita

CONTACT P. T. Akonor papatoah@gmail.com Food Technology Research Division, CSIR-Food ResearchInstitute, P. O. Box, M20, Accra, Ghana.

JOURNAL OF CULINARY SCIENCE & TECHNOLOGY2018, VOL. 16, NO. 1, 52–65https://doi.org/10.1080/15428052.2017.1333937

© 2018 Taylor & Francis

consumption of the crop were estimated as 1.3 million MT and 40 kg/annum,respectively (SRID, 2015).

The search for alternatives to partially or fully replace wheat flour inbakery and other culinary applications has become necessary for economic,nutritional, and or health reasons. Rodrick (2008) observed that wheatprices on the world market have become volatile and were noted to havedoubled between 2005 and 2007, and increased by 26% between October2011 and October 2012. The instability in the commodity’s pricing places astrain on developing economies, who rely heavily on imports to satisfy theirwheat needs. Using flours from root and tuber crops to partially substitutewheat flour has been suggested as one of the prospective ways around thischallenge. These root and tuber crops are readily available and relativelyless expensive. Their flours have the potential of enriching the nutrientstatus of the resulting composite flour. Additionally, consumers who areallergic to wheat gliadins and suffer from celiac disease stand to benefit,since exposure to this wheat protein is minimized when flour from not-protein sources is used.

Cocoyam flour could be used in the production of bakery and pastry products.However, the acceptability of these products largely depends on the level ofsubstitution. This greatly affects sensory and other quality properties of thesefood products. There is the need therefore to establish these production indicesthrough in-depth research to facilitate food product development from thesecrops which have the potential of partially substituting wheat flour. The aim ofthis study was therefore to determine the nutritional and functional properties ofcocoyam flour and evaluate the organoleptic properties of model pastry productsmade from wheat-cocoyam composite flour.

Materials and methods

MaterialsMature red cocoyam (Xanthosoma sagittifolium) was sourced from a rootcrops market, sorted and cleaned, and stored at room temperature (28°C) injute sacks prior to processing into flour. Soft wheat flour and other bakeryingredients were procured from a local supermarket.

MethodsCocoyam flour. Cocoyam roots were washed under running potable waterand peeled with a stainless steel knife. Peeled roots were washed and cut intothin slices (5 mm), and washed once again before spreading thinly on dryingtrays. The slices were dried in a mechanical dryer (Apex, UK) at 60°C for12 hrs. The dried cocoyam slices were milled into flour using a hammer mill(Christy and Norris Ltd., Surrey, UK) to pass through a 250 µm sieve and theflour sealed in flexible HDPE bags for use later.

JOURNAL OF CULINARY SCIENCE & TECHNOLOGY 53

Composite flour. The cocoyam flour was mixed with soft wheat flour (fordough nut and cookies) or hard wheat flour (for bread) in proportions (w/w)described in Table 1 to produce cocoyam-wheat flour composite.

Proximate composition of cocoyam flour. Cocoyam flour was analyzed, intriplicate, for moisture, ash, crude fat, and crude protein, respectively, usingapproved methods 945.38B, 900.02A, 945.38F, and 979.09 of the AOACInternational (AOAC, 2000). Total carbohydrate was estimated by difference.

Physico-chemical and functional properties of flour. pH of the flours wasmeasured with a pH meter (Jenway, 3330, England) (AOAC, 2000).

Color

Color of the flour was determined using a Minolta Chroma meter (CR-310Minolta, Japan). The device was calibrated with a reference white porcelaintile (L0 = 97.63, a0 = 0.31 and b0 = 4.63) before the determinations. Floursamples (120 g) were weighed into a clear and transparent pyrex petri dishes(ensuring a flat surface) from which readings were taken. Color of thevarious flours was described using the L a b system, where L* is a measureof lightness, a* defines components on the red-green axis, and b* definescomponents on the yellow-blue axis. All determinations were done in tripli-cates and the means and standard error reported.

Water and oil absorption capacity

Water and oil absorption capacities of the flours were determined byAfoakwa, Budu, Asiedu, Chiwona-Karltun, and Nyirenda (2012). Briefly,1 g of flour was mixed with 10 mL of distilled water for 30 s. The sampleswere allowed to stand at room temperature (28°C) for 30 min, after whichthey were centrifuged at 3000 rpm (Hermle Z 206A, Germany) for 30 min.The volume of the supernatant was recorded and water absorption capacitycalculated as the difference between the initial volume of water added to theflour and the volume of the supernatant. For oil absorption capacity, thesame procedure was followed, using vegetable oil instead of distilled water.

Table 1. Proportion of cocoyam flour and wheat flour in composite flour.Sample Cocoyam flour (%) Wheat flour (%)

1 0 1002 5 953 10 904 15 855 20 806 30 70

54 P. T. AKONOR ET AL.

Swelling power and solubility index

Aqueous flour dispersions (2.5%) were made in centrifuge tubes, capped toprevent spillage and heated in a water bath with shaker (GRANT OLS 200,England) at 85°C for 30 min. After heating, the tubes were cooled to roomtemperature and centrifuged at 2200 rpm (Hermle Z 206A, Germany) for15 min. Precipitated paste was separated from the supernatant and weighed(Wp). The supernatant was evaporated in a hot air oven (GallenkampHotbox, England) at 105°C and the residue weighed (Wr). Determinationswere done in triplicates and Swelling Power (SP) and Solubility index (SI)were respectively calculated as:

SP ¼ wt of precipitated paste Wpð Þwt of sample Woð Þ � wt of residue in supernatant Wrð Þ

SI ¼ wt of residue insupernatant Wrð Þwt of sample Woð Þ x100

where Wo is the weight of sample.

Emulsion capacity

Emulsion capacity was determined by Acuna, Gonzalez, and Torres (2012).Five milliliters of flour dispersion in distilled water (10 mg/mL) was homo-genized with 5 mL of oil for 1 min. The emulsion was centrifuged at1,100 rpm for 5 min. The height of emulsified layer (EL) and height of thetotal content (TC) of the tube were measured. Emulsion capacity wasexpressed as;

EC ¼ ELTC

� 100

Bulk density

Bulk density was determined by Ashogbon and Akintayo (2012). A graduatedmeasuring cylinder was weighed and filled to 10 mL with flour. This wasdone by gently tapping the bottom of the cylinder on the laboratory benchseveral times until there was no further diminution of the sample level afterfilling to the 10 mL mark. The bulk density of flour samples was thereaftercalculated by the following relation:

Bulk density ¼ Weight of sample gð ÞVolume of sample mLð Þ

JOURNAL OF CULINARY SCIENCE & TECHNOLOGY 55

Pasting properties of flour

The pasting properties of the various flours were determined on an 8% slurryof flour using a Brabender Viscoamylograph (Viskograph-E, BrabenderInstrument Inc., Duisburg, Germany) equipped with a 1,000 cmg sensitivitycartridge. The suspension was heated from 50°C to 95°C at a rate of 1.5°C/min, held at this temperature for 15 min, cooled to 50°C at a rate of 1.5°C/min, and held at this temperature for 15 min. The viscosity profile indicesrecorded included the following: pasting temperature, peak viscosity, viscos-ity at 95°C, viscosity after 30 min hold at 95 (95°C-hold), viscosity at 50°C,and viscosity after 15 min hold at 50°C (50°C-hold), breakdown, and setback.

Model pastry products

The composite flours were used to produce three common pastry products,namely doughnuts, bread, and cookies, according to methods described byTortoe et al. (2014). In brief, doughnuts were processed by rubbing margarineinto previously and uniformly mixed dry ingredients before milk and beaten eggswere added. The mixture was whipped further and deep fried by dropping scoopsof the mixture in moderately hot oil. In the case of bread, the ingredients(composite flour, margarine, sugar, salt, and instant baking yeast) were mixedthoroughly for 3min at low speed before kneading into a soft dough. The kneadeddough was allowed to rise for 30 min before panning and proofing at roomtemperature for 120 min. The loaves were baked at 175°C for 20 min. For cookies,margarine and sugar were creamed until light and fluffy. Flour and baking powderwere gradually added to the cream, mixed uniformly and piped through a cookiescutter and baked at 175°C for 25 min. The pastry products were allowed to cool atroom temperature for 1 h before the sensory evaluation.

Sensory evaluation

Fifty untrained panelists, who regularly patronize pastry products and had pre-vious experience in sensory evaluation, were made to assess doughnut, bread andcookies made from the composite flours. The panelists (27 females and 23 males)were non-smokers, aged between 21 and 54 years, selected based on availabilityand readiness to partake in the evaluation session. A 9-point hedonic scale (Stone& Sidel, 2004), with 1 representing dislike extremely and 9 representing likeextremely, was used for the evaluation. Samples (30 g bread, 30 g doughnut and26 g cookies) were presented on disposable rigid polypropylene platters labelledwith a 3-digit code. Panelists were served with evaluation samples following arandomized designmatrix generated using XLSTAT version 2014. The assessmentwas based on common attributes of pastries such as appearance, aroma, taste,texture, sponginess (for doughnut and bread), and overall acceptability. Panelists

56 P. T. AKONOR ET AL.

were provided with a piece of unsalted cracker to clean their mouths and water torefresh their palate before tasting subsequent samples.

Statistical analysis

The data obtained from the study was analyzed for differences usingANOVA, and where present, these differences were separated usingDuncan’s Multiple Range Test (SPSS 17.0.1, SPSS Inc. USA). Significantdifference was defined as p < 0.05.

Results and discussions

Proximate composition of cocoyam flour

Proximate composition of the cocoyam flour indicated that it contains 8.5 g ofproteins, 2.4 g of ash, and 0.5 g of fat per 100 g of flour (7.3% moisture). Being astarchy staple, it is carbohydrate-dense and was observed to supply nearly400 kcal of energy per 100 g of flour. The protein content of cocoyam flourwas higher than the values reported for cocoyam (3.94–4.09 g/100g) by Sefa-Dedeh and Sackey (2004) as well as the 1–2% reported by Charles, Sriroth, andHuang (2005) for cassava. Ash, on the other hand, was lower, while fat obtainedin this study was comparable to values obtained by the same authors. Variationsin amounts of nutrients in this study, compared to previous ones, may be due todifferences in agronomic and environmental conditions under which the cropwas grown. Apart from fat content, the results obtained for the other nutrientswere also higher than those reported by Sefa-Dedeh and Sackey (2004) for taro.Moisture content relates directly to drying method and time as well as storageconditions (van Hal, 2000). Moisture of the flour was less than 10%, whichmakes desirable for use in pastry products. Low moisture content enhances thekeeping properties of flour because it prevents the growth of micro-organismsand also reduces the incidence of physical and chemical reactions that are likelyto cause deterioration and lower flour quality (Aguilera, Del Valle, & Karel,1995; van Hal, 2000). Moisture of the composite flours was observed to reducegradually as more cocoyam flour was introduced. The lowering effect of thecocoyam flour in the composites was not pronounce between successive 5%increment levels.

Physico-chemical and functional properties of flour

pH, color, and other physico-chemical properties are usually considered asindicators of flour quality. Therefore changes in these parameters may affectfunctionality of the flour. pH of the flours were within the range for low acidfoods (Thomas & Atwell, 1999) and was significantly lower for cocoyam flour

JOURNAL OF CULINARY SCIENCE & TECHNOLOGY 57

compared to wheat flour. A general trend of an increase in pH was observedamong the composite flours. The pH of these composite flours were alsowithin the range for low acid foods. Acidic flours are generally undesirable inthe manufacture of bakery and other pastry products.

Color has been described by Wrolstad and Smith (2010) as being influentialon consumer opinion about food. In flours, it is considered critical, since itaffects marketing and acceptability of products made from them (van Hal,2000). The color of cocoyam flour was darker, reddish, and less yellowcompared to wheat flour (Table 2). Redness of cocoyam flour may be due tothe anthocyanins, which are widely distributed in the araceae family (Perneelet al., 2007) to which cocoyam belongs. The addition of cocoyam flourimparted significant changes (p < 0.05) to the color of the composite flourblends. Here, a trend of increasing darkness and redness and a reduction inyellowness was noticed when the proportion of cocoyam flour increased.

Water binding capacity of the cocoyam flour was significantly higher thanwheat flour (Table 3). Differences in water binding capacity (WBC), swellingpower (SP), and solubility index (SI) of flours from different sources havebeen ascribed to variations in starch content and structure, amylose-amylo-pectin ratio, and their arrangement within the starch granule (Zhang, Chen,& Zhang, 2011). Starches with loosely associated amylose and amylopectinhave been shown to have high water binding capacity. Water binding capa-city of the 5% composite flour was 53 g/g, and this increased gradually to

Table 2. Physico-chemical properties of cocoyam, wheat and cocoyam-wheat composite flours.

Flour (CF:WF) pH

Color

L a b

5:95 6.16 ± 0.05a 90.97 ± 0.03b −0.61 ± 0.01f 7.48 ± 0.03f

10:90 6.18 ± 0.02a 89.55 ± 0.05c −0.52 ± 0.03e 6.91 ± 0.01e

15:85 6.22 ± 0.01b 88.83 ± 0.13d −0.40 ± 0.03d 6.54 ± 0.11d

20:80 6.24 ± 0.02b 88.58 ± 0.23e −0.34 ± 0.05c 6.02 ± 0.01c

30:70 6.30 ± 0.01c 88.21 ± 0.14e −0.25 ± 0.02b 5.91 ± 0.13b

100% CF 6.53 ± 0.01d 86.06 ± 0.01a 1.81 ± 0.01g 5.48 ± 0.02a

100% WF 6.64 ± 0.01e 91.23 ± 0.12b −1.35 ± 0.01a 8.69 ± 0.02g

CF = Cocoyam flour, WF = Wheat flour. *Means with different superscripts are significantly different atp = 0.05.

Table 3. Functional properties of cocoyam, wheat and cocoyam-wheat composite flours.Flour (CF:WF) WBC SP SI Bulk Density Emulsion Capacity

5:95 53.2 ± 2.0b 5.01 ± 0.14ab 1.49 ± 0.11a 0.79 ± 0.01b 50.0 ± 3.4b

10:90 54.2 ± 2.0b 5.06 ± 0.05b 1.49 ± 0.24ab 0.79 ± 0.01b 50.0 ± 1.0b

15:85 55.8 ± 0.4b 5.18 ± 0.01c 1.69 ± 0.02b 0.80 ± 0.01c 50.0 ± 2.7b

20:80 57.3 ± 0.1bc 5.30 ± 0.08c 1.71 ± 0.10b 0.81 ± 0.01c 46.0 ± 2.7a

30:70 62.2 ± 0.7c 5.32 ± 0.07c 1.89 ± 0.09c 0.82 ± 0.01c 50.0 ± 0.0b

100% CF 81.2 ± 0.3d 5.89 ± 0.04d 2.90 ± 0.31d 0.81 ± 0.01c 51.6 ± 1.4c

100% WF 45.1 ± 0.1a 4.81 ± 0.10a 1.55 ± 0.05a 0.77 ± 0.01a 48.4 ± 1.4ab

CF = Cocoyam flour, WF = Wheat flour. *Means with different superscripts are significantly different atp = 0.05.

58 P. T. AKONOR ET AL.

62 g/g when the proportion of cocoyam was increased to 30%. High waterbinding capacity is important to enhance cohesiveness and dough handlingduring baking operations. The swelling power of cocoyam flour was alsosignificantly higher than wheat flour. This observation is explained by differ-ences in morphological structure of starch granules from these two commod-ities. For example previous studies by Tester and Morrison (1990) revealedthat amylose restricts swelling. Therefore, differences in this componentalone may cause variations in swelling power. The composite blends alsohad higher swelling power than wheat flour, and this increased further whenthe proportion of cocoyam flour was increased. The addition of cocoyamflour therefore improved the swelling power of the composite flour blends.The solubility index ranged between 1.5 to 2.9 g/g of flour for the compositeblends and individual flours. Although the addition of cocoyam flour alsoimproved solubility index of the composite blends, this only became signifi-cant beyond 10% inclusion level.

Bulk density and emulsion capacity of the pure flours and their compositesranged from 0.77 to 0.82 and 46.0 to 51.6, correspondingly, for these two para-meters. Bulk density is dependent on particle size, reflects heaviness of flour, and isan indicator of product porosity (Akubor, 2013; Ocloo, Bansa, Boatin, Adom, &Agbemavor, 2010), whereas emulsion capacity is a property of proteins and as suchis influenced by protein content and its quality. The results indicate that cocoyamflour was considerably bulkier (0.81) than wheat flour (0.77) and therefor anincrement of cocoyam flour in the composite resulted in an increase in its density.As noted by Udensi and Eke (2000), high bulk enhances dispersibility and reducespaste thickness. Emulsion capacity was much higher (51.6%) in cocoyam flourthan the wheat flour (48.4%). Replacement of a part of wheat flour with cocoyamflour resulted in an increase in emulsion capacity. Compared to the emulsioncapacity of wheat flour, this increment, however, was not significantly (p > 0.05)affected by varying amounts of cocoyam flour.

Pasting properties of the flours

Visco-elastic properties serve as a unique way of finger-printing starches in floursbecause it shows their pattern of viscosity and aids in the prediction of starchbehavior during and after cooking. Results of the pasting properties of cocoyamflour, wheat flour, and their composite flours are summarized in Table 4. Pastingtemperature represents the point at which starch granules begin to swell up whenthey are subjected to heating, and this leads to the formation of a viscous paste(Afoakwa, Adjonu, & Asomaning, 2010). There was no significant difference(p > 0.05) in pasting temperature of the two main flours (cocoyam and wheat).However, some differences were observed among the composites.

PV was 78.0 and 421.5 BU, correspondingly, for wheat flour and cocoyamflour. This observation clearly agrees with Collado and Corke’s assertion that

JOURNAL OF CULINARY SCIENCE & TECHNOLOGY 59

Table4.

Pastingcharacteristicsof

cocoyam,w

heat

andcocoyam-wheat

compo

site

flours.

Flou

r(CF:WF)

PT(°C)

PVV95

HPV

95V50

CPV50

Breakdow

nSetback

5:95

77.9

±0.9a

bc

93.5

±0.5b

68.0

±0.0b

63.0

±0.0b

101.0±1.0b

100.0±1.5b

30.5

±0.5a

38.0

±0.5a

10:90

76.8

±0.3a

107.5±2.5c

80.5

±1.5c

72.0

±2.0b

155.5±7.5c

104.5±7.5b

35.5

±0.1b

43.5

±0.5b

15:85

78.4

±0.2d

149.5±1.5d

119.0±2.0d

112.5±1.5c

171.5±0.5d

149.5±0.5c

36.5

±0.5b

59.0

±1.5c

20:80

78.8

±0.0a

b165.5±1.5e

134.5±0.5e

117.0±1.0d

186.5±3.5e

168.0±3.0d

48.5

±2.5c

69.5

±0.5d

30:70

78.9

±0.1a

bc

172.5±4.5e

150.5±0.5f

118.5±0.5d

197.0±4.0e

173.0±3.0d

54.0

±0.0d

78.5

±1.5e

100%

CF78.2

±0.1b

c421.5±3.5f

403.5±3.5g

315.5±8.5e

394.5±0.5f

363.5±3.5e

106.0±2.5e

79.0

±1.0e

100%

WF

78.1

±0.7b

c78.0

±0.0a

55.5

±0.7a

48.5

±9.2a

95.5

±2.1a

85.0

±2.8a

29.5

±0.6a

47.0

±0.0b

With

inacolumn,

means

bearingdiffe

rent

superscriptsaresign

ificantlydiffe

rent

(p<0.05).PT

=PastingTemperature,PV=Peak

viscosity,H

PV=Hot

PasteViscosity,C

PV=Co

olPasteViscosity,B

reakdo

wn,

andsetbackviscosity.P

astin

gprop

ertiesweremeasuredin

BrabenderUnits

(BU)

60 P. T. AKONOR ET AL.

starches from root crops free swelling compared to starches from cereals(Collado & Corke, 1998). The values obtained for cocoyam flour was lowerthan the range (930–1370 BU) reported by Sefa-Dedeh and Sackey (2002) forthe red variety cocoyam starch. Among the composites, PV ranged between93.5 and 172.5 BU, with increasing proportion of cocoyam flour yieldinghigher peak viscosities. This is ascribed to the free swelling nature of thecocoyam starches being conferred on the composite flour as it replacessignificant portions of wheat flour. A slight reduction in viscosity wasobserved at 95°C for the main flours as well as their composites. A furtherdrop in torque was noticed after holding at 95°C under shear forces for allthe flours. The decline was greater in 100% cocoyam flour compared towheat flour and confirms the assertion that tuber starches exhibit very lowshear stability and reduced apparent viscosity after reaching the maximumvalue (Collado & Corke, 1998; Singh, Singh, Kaur, Sodhi, & Gill, 2003).Progressively, the composite flours were seen to exhibit higher breakdownin viscosity as the ratio of cocoyam inclusions increased (Table 4). Thisobservation suggests that increasing proportions of cocoyam reduces theresistance of the composite flour to shear forces during cooking (Beta &Corke, 2001). Setback values indicate the retrogradation tendency of starchand this is mainly dominated by amylose gelation. This phenomenon israther undesirable in bakery products because it contributes significantly toaberrations such as staling (Karim, Norziah, & Seow, 2000). Generally,significantly higher (p < 0.05) setbacks were seen in composite flours withhigher proportions of cocoyam flour. High setback has been associated withhigh degree of affinity among starch molecules caused by hydrogen bonding(Sefa-Dedeh & Sackey, 2002).

Sensory evaluation of pastry products

Results of the sensory evaluation indicates slight differences in the panelistrating of doughnuts made from composite flour (Table 5a). Doughnuts madefrom wheat flour (control) were rated highest in all attributes, while thosemade from 30% composite flour received the lowest (except sponginess)compared to the rest of the products. A general trend of a somewhat evenand better rating was observed for lower replacement level (up to 15%)compared to composites with higher amounts (20% or more) of cocoyam flour

In the case of bread (Table 5b), samples made from 10% composite wererated higher in all attributes, compared to the control and other composites.Rating of products from this flour compared well with those from wheatflour as well as the 5% composite. Loaves made from 15–20% compositeflours were similar, as indicated by the scores assigned by panelists. Noobvious trend was established regarding the effect of an increase or decreasein cocoyam proportion on the various attributes. Clearly, however, bread

JOURNAL OF CULINARY SCIENCE & TECHNOLOGY 61

made from 30% cocoyam-wheat composite flour was the least desirable bypanelists

Sensory scores of attributes used to assess the cookies are presented inTable 5c. Generally, the attributes were rated similarly for cookies made fromthe different cocoyam-wheat composite flours as well as 100% wheat flour. Forcolor, however, rating for 20 and 30% cookies was much lower compared to allthe others. For this attribute alone, cookies from wheat flour performed betterthan those made from the composite flour. Among cookies made from thecomposites flours, scores for the various attributes reduced with an increase inthe proportion of cocoyam flour, especially for taste and texture. Cookies madefrom 10% composite proved to be the one with the most preferred attributes,whereas 30% composite resulted in the least preferred cookies.

Table 5a. Sensory scores for doughnuts made from cocoyam-wheat flour composite and“control”.Flour (CF:WF) Appearance Color Aroma Crust Sponginess Taste

5:95 8.1 ± 0.3bc 8.1 ± 0.2c 7.8 ± 0.1b 7.5 ± 0.2b 7.3 ± 0.2ab 7.5 ± 0.1b

10:90 7.8 ± 0.1b 7.7 ± 0.1b 7.7 ± 0.2b 7.1 ± 0.2a 6.8 ± 0.2a 7.4 ± 0.2ab

15:85 7.7 ± 0.2b 7.7 ± 0.1b 7.8 ± 0.1b 7.4 ± 0.2b 7.5 ± 0.1b 7.8 ± 0.1c

20:80 7.8 ± 0.1b 7.5 ± 0.1b 7.9 ± 0.1b 7.1 ± 0.1a 7.0 ± 0.1a 7.1 ± 0.1a

30:70 7.3 ± 0.2a 7.1 ± 0.1a 7.4 ± 0.1a 7.1 ± 0.1a 7.1 ± 0.1a 6.9 ± 0.3a

100% WF 8.5 ± 0.2c 8.3 ± 0.1c 8.1 ± 0.1b 7.7 ± 0.2b 7.5 ± 0.2b 8.0 ± 0.3c

100% WF = “control”WF=wheat flour, CF=Cocoyam flour. For each attribute, means bearing different superscripts indicatesignificant differences (p<0.05).

Table 5b. Sensory scores for bread made from cocoyam-wheat flour composite and “control”Flour (CF:WF) Appearance Color Aroma Crust Sponginess Taste

5:95 8.0 ± 0.2c 8.0 ± 0.2c 7.4 ± 0.3ab 7.6 ± 0.1b 7.9 ± 0.1c 7.8 ± 0.1b

10:90 8.1 ± 0.2c 8.1 ± 0.1c 7.9 ± 0.3b 7.5 ± 0.1b 8.0 ± 0.2c 8.2 ± 0.2b

15:85 7.7 ± 0.3bc 7.8 ± 0.1c 7.4 ± 0.2ab 7.5 ± 0.2b 7.4 ± 0.2b 7.3 ± 0.2a

20:80 7.8 ± 0.2bc 7.9 ± 0.1c 7.6 ± 0.1b 7.4 ± 0.1b 7.1 ± 0.2b 7.5 ± 0.3a

30:70 7.0 ± 0.2a 6.9 ± 0.1a 7.2 ± 0.1a 6.7 ± 0.2a 6.5 ± 0.2a 7.0 ± 0.2a

100% WF 7.6 ± 0.2b 7.5 ± 0.2b 7.8 ± 0.2b 7.3 ± 0.3b 7.9 ± 0.2c 8.0 ± 0.1b

100% WF = “control”WF=wheat flour, CF=Cocoyam flour. For each attribute, means bearing different superscripts indicatesignificant differences (p<0.05).

Table 5c. Sensory cookies for bread made from cocoyam-wheat flour composite and “control”Flour (CF:WF) Appearance Color Aroma Texture Taste

5:95 7.9 ± 0.2ab 8.2 ± 0.1b 8.0 ± 0.1a 8.4 ± 0.2b 8.3 ± 0.2c

10:90 8.2 ± 0.2b 8.3 ± 0.2b 8.4 ± 0.2ab 8.2 ± 0.2b 8.2 ± 0.2c

15:85 8.3 ± 0.1b 8.3 ± 0.2b 8.2 ± 0.1a 8.1 ± 0.2ab 8.1 ± 0.2bc

20:80 7.5 ± 0.2a 7.5 ± 0.2a 7.7 ± 0.3a 8.0 ± 0.2ab 7.9 ± 0.2bc

30:70 7.7 ± 0.2a 7.5 ± 0.2a 7.9 ± 0.1a 7.7 ± 0.2a 7.4 ± 0.2a

100% WF 8.2 ± 0.1b 8.3 ± 0.2b 8.2 ± 0.2a 7.7 ± 0.2a 7.7 ± 0.2ab

100% WF = “control”WF=wheat flour, CF=Cocoyam flour. For each attribute, means bearing different superscripts indicatesignificant differences (p<0.05).

62 P. T. AKONOR ET AL.

Acceptability

Overall acceptability of the three pastry products as rated by the 50-memberpanel (Figure 1) clearly reveal that products made from the compositescompared well with those made from wheat flour only (control), particularlythose made from 5 to 15% composites. For doughnuts, acceptability ratingfor 20–30% replacement levels were significantly lower (p < 0.05) than thecontrol. Conversely, samples from 5 to 15% were comparable to the control,making this level of substitution the most suitable for the production ofdoughnuts. A sharp reduction (from 8 to 7) in preference for bread wasnoticed beyond 10% cocoyam flour inclusion level. It is worthy of mentionthat, at 15%, there was still no significant differences (p > 0.05) in preferencefor “composite” bread and “control” bread. This indicates that up to 15% ofwheat flour may be replaced with cocoyam flour in bread bakery applica-tions. Cookies made from all the composite flours showed remarkable pre-ference similarities to those made from 100% wheat flour. This observationnotwithstanding, increasing the proportion of cocoyam flour slightly loweredthe preference rating of cookies.

Conclusion

Cocoyam flour has been shown to possess ample amounts of proteins, minerals,and fat, which makes it an important source of these nutrients when used topartially replace wheat flour for culinary applications. Its physico-chemical andfunctional properties were also found to be desirable for use in composite flour

aa

abbb

c

a

bbc

cc

ca

a abbccc

0

1

2

3

4

5

6

7

8

9

Doughnut Bread Cookies

Acce

pta

bil

ity

Pastry product

5% 10% 15% 20% 30% Control

Figure 1. Acceptability of model pastry products. 5% = 5% cocoyam flour and 95% wheat flour,10% = 10% cocoyam flour and 90% wheat flour, 15% = 15% cocoyam flour and 85% wheatflour, 20% = 20% cocoyam flour and 80% wheat flour, 30% = 30% cocoyam flour and 70%wheat flour, Control = 100% wheat flour. Error bars represent Standard Error of Means.Comparisons are based on differences within products.

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blends. These blends hadproperties intermediary betweenpure cocoyam flour andwheat flour. Replacement of wheat flour with cocoyam flour caused significantchanges in color, WBC, SP, and SI, as well as viscoelastic properties of thecomposite flour. Sensory evaluation of the three pastry products revealed that upto 30% of cocoyam flour can replace wheat flour for the production of cookies. Inthe case of doughnuts and bread, up to 20%wheat-cocoyam composite flour couldbe applied, without a compromise on consumer preference.

Acknowledgments

The authors are grateful for sponsorship from the West Africa Agricultural ProductivityProgramme (WAAPP2A) – Ghana.

Conflict of interest

The authors hereby state that there is no conflict of interest regarding this publication.

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