This is not a peer-reviewed article. Electronic-only Proceedings of the International Conference on Crop Harvesting

and Processing, 11-14 February 2007 (Louisville, Kentucky USA) Publication Date, 11 February 2007.

ASABE Publication Number 701P0307e

PROBLEMS OF SHEA BUTTER PROCESSING IN AFRICA

A. F. Alonge, A. M. Olaniyan

ABSTRACT

Shea nut (Vitellaria paradoxa) is one of the most important oil-bearing materials.

It is important for its nutritional values as a source of food, for industrial purpose and

pharmaceutical use. Therefore, improvement in the method of extraction is important.

More shea butter will be available if the method of processing and handling can be

improved. The problem of shea butter processing starts with harvesting which is usually

collected after dropping from the tree to the ground. Other problems include postharvest

storage because of lack of facilities for immediate parboiling after harvest. Washing,

drying and cracking of the nut to recover the kernel also constitute a menace because of

inadeaquate facilities. The milling and roasting of the kernel prior to butter extraction is

also laborious and tedious. The extraction process which involve mixing of the milled

product by trampling, cooking of the mass and scooping of the butter and clarification is

cumbersome and energy sapping procedure. Consequent upon these myriad of problems

for local producers and processors, research efforts are being geared towards alleviating

the problems. Efforts made are hereby highlighted in Nigeria and sub-Saharan region of

Africa. Suggested solutions and recommendation are hereby made. The use of hydraulic

press that will press this oil out at high temperature and pressure will bring out a good

result in the extraction of Shea butter.

Keywords: shea nut, kernel, processing, butter, extraction, problems,

The authors are Dr. A. Folarin Alonge, ASABE Member, Engineer, and Dr. Adesoji M. Olaniyan, are

both of the Department of Agricultural Engineering, University of Ilorin, Ilorin, Nigeria. Corresponding

author: A. Folarin Alonge, Dept. of Agricultural Engineering, University of Ilorin, P.M.B 1515, Ilorin,

Nigeria. Phone: 234-803-3603462; email: falonge6@ yahoo.com

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INTRODUCTION

Shea nut (vitellaria paradox) is of a botanical family sapoteceae and has a

botanical name Butryospermum parkli. Other names are Karite (French), Nku (Ghana),

Shea butter tree and bambuk butter tree. The tree can be found growing naturally in the

southern region of the sahel and the northern regions of the Guinea Zone. It thrives in

savanna areas where oil palm cannot grow due to low rainfall (GTZ, 1986). The major

producing countries are West African countries (Mali, Burkina fasso, Benin, Senegal,

Ivory Coast, Ghana and Nigeria). Using landsat remote sensing image in Mali, 18 million

shea butters trees were counted over a distance of 20km (Fleury, 2000).

Trees may suffer from feat spot, which is caused by pestalotia heterospora and

fusidadium butryrospermi (Godwin and Spensely, 1971). Harvesting generally takes

place between June and August, peaking during July. Berries ripen and fall to the ground.

They are gathered by children and women and stored in ditches for collection. The

production of shea butter oil has been largely a job for women and children in the middle-

belt of savanna zone of Nigeria. The shea butter (vitellaria paradox) is found from shea

butter tree grown widely within the savanna forest belt of Nigeria between latitude 60N

and 130N

The crop is ellipsoidal in shape and has a white scar at one side. The main size of

the nut is about 35mm long x 25mm wide x 23mm thick. There is a kernel inside the nut

which fits properly into the shell and is at about 32mm large, 23mm wide x 21mm thick

in size. It has a uniform shell of about 1mm thick (Oje and Olaniyan, 1999). The fruit is a

greenish brown fruit of shea butter tree. It comprises an outer fleshy mesocarp enclosing a

nut. The nut is thin-shelled and enclosed with the oil bearing kernel (Babatunde and

Olaoye, 1997) oil obtained from sheanut contains some acids coke palmitic acid, stearic

3

acid, oleic acid and linoleic acid. Shea butter is soft and sold at tropical ancient

temperature. It is yellowish white in colour and has a strong smell (Tessy, 1992).

The nut is processed to produce shea butter, which is a very important vegetable

oil in West Africa. The high allantoic content in the butter also makes it a useful base for

local pharmaceutical preparations. The butter is also used to make soap and in the

construction industry. It is used on the walls of houses to prevent them from being

washed away during the rainy season. Shea butter can also be used to form a cocobutter

substitute (Fleury, 2000). According to Olaniyan and Oje (1999 & 2002), the cake from

which the oil is extracted is used in livestock feed production. Momodu (1987)

discovered that shea butter is used for curing headache, leprosy and also used to aid

childbirth. In Europe, shea butter is used for making cosmetics and various types of cream

(Purseglove, 1974). The cake obtained after oil extraction can be used as fuel.

Shea butter is an important oil like other vegetable oils and it is even one of the

most important vegetable oils because of its quality. Due to the fact above, there is need

to improve on the extraction i.e both the quality and the quantity of the product. A

problem identified is a problem solved hence it is only when we identify the problems of

extraction of this vegetable oil that we can have solutions to them. Therefore, the main

objectives of this project are to identify problems, which could be encountered in the

extraction of shea butter and to proffer possible solutions to the problems.

LITERATURE REVIEW

Bohle and Reddy (1993) worked on mechanical expression of oil from mustard

seed. The expression of oil from mustard seeds was carried out using a laboratory

hydraulic press with a press unit assembly. From the experiment, he discovered that the

4

oil yield was significantly affected by moisture content of milled mustard seeds, applied

pressure and pressing time.

According to Akintunde et al (2001) and Olaniyan (2006), the particle size,

heating temperature and time, moisture content, applied pressure and duration of pressing

should be studied in other to achieve efficient expression of oil because the processing

factors are observed to be crop specific since they have different effects on different oil

seeds. The processing factors investigated have been identified as having a significant

effect one the oil expression from soyabean seed. Extraction of oil from Niger seed using

a small expeller could be improved significantly through the applications of pre-

extraction heating and roasting treatment. However, proper storage and handling of the

raw material or the use of freshly harvested seeds are equally recommended (Ayenew,

2000).

Deformation and energy absorbed at rupture increase with increasing temperature

from 40 to 800C while further increase in temperature from 80 to 1000C leads to decrease

in load, deformation and energy absorbed at rupture. However, strain at rupture didn’t

follow any regular trend with regard to changes in temperature. This response of strength

parameters of rupture to changes in temperature can be attributed to the fact that, with

increasing temperature, case handling results due to loss of moisture in the crop coupled

with drying process. However, further increase in temperature beyond certain value

weakens the crop structurally. The overall effect is the reduction in hardness of the seed,

which could be an advantage in grinding/crushing operation during shea butter extraction

(Olaniyan, 2002).

The effect of heating time on strength parameters at rupture revealed that load,

deformation, energy absorbed and strain at rupture decreases with increase in heating

time from 10 to 30 mins, this shows that shea kernel can easily be crushed when it is

5

subjected to a prolong heat treatment since this can be lead to structural weakness in the

material (Olaniyan, 2002).

Deformation energy absorbed and strain at rupture had the highest value when

shea kernels were compressed in the axial loading position while load at rupture had the

highest value in the transverse loading position. Load, energy absorbed and strain at

rupture had the lowest values. When shea kernels were compressed in the lateral loading

position while deformation at rupture had the lower value in the transverse loading

position. Since loading position had effect on the strength properties at the rupture point

of shea kernels under compressive loading, therefore, for effective size reduction,

operation during shea butter recovery, from shea kernels, the manner of loading the

kernel into the size reduction equipment should be taken into consideration (Olaniyan,

2002).

SHEA BUTTER PROCESSING

The equipment for primary processing include pan for boiling water, drying mat,

hammers, pestles, winnowing basket, and claypot. The pulps of the harvested berry are

being crushed under foot after fermentation. This berry (almond) sticks to the shell wall.

To separate them, the nuts are immersed in boiling water and sun dried for a few days.

During the drying stage, he berries become detached. Nuts can now be stored for months

without deterioration.

Shelling is carried out using stone, hammers and pistles. Winnowing is achieved

by holding basket filled with nut at arm length and gradually employing them. If there is a

strong wind, the piece of shell will be blown away, if not, then the operation is repeated

many times (Fleury, 2000). The day prior to oil extraction, the shelled almonds are dried

again from a moisture content of 40 to 50% to 6 to 7% (Godwin and Spensley 1971).

6

There are two methods for oil extraction, a traditional village process and a

mechanical procedure. The traditional process (Figure 1) involves many time consuming

stages. After drying, the kernels are crushed by simultaneous strokes, in a mortal. The

paste that is gradually formed needs to be kept at a temperature of about 400C. shea butter

tend to solidify between 34 to 380C. Once the paste becomes a fluid, it is strained and

heated in a pan. A kneading process using a polished stone takes place to break up oil cell

and ease oil extraction. The paste is then mixed with water to separate the remaining oil.

Afterwards it is rapidly mixed by hand until it starts to cover itself with a white

emulsion of fat. Once this is achieved, the paste is left to rest. The oil that floats to the

surface is scooped off, and poured into a container filled with lukewarm water for

decantation. During decantation, a white film form over the top of the surface, this is shea

butter. It is separated and heated in a cauldron to evaporate remaining water and allow

heavy impurities to settle at the bottom. The butter is left overnight to rest. Traditionally,

it is then divided and wrapped in leaves for selling or for storage. The butter will last for

many years if kept away from light and heat as it is resistant to oxidative rancidity

(Fleury, 2000).

A less time consuming method of preparing shea butter has been developed by the

Royal Tropical Institute in the Netherlands. The process has only four stages (Figure 2).

The kernels are pounded to a fine powder, which is then heated to a temperature of

1000C. It is kept hot in a hot air oven for one hour before being pressed in a hydraulic

hand press. The fat, which is obtained, is cleared of all other residues by boiling with

Okro, Lemon, Juice and water (UNIFEM, 1987). It should be noted that using a shea nut

press, not only alleviates time consuming process but also improves the fat output. For

example, using a shea press fat output will be between 40 to 45%. Whereas fat output

using the traditional method will be about 25% (Niess, 1983).

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Harvested fresh fruit

Figure 1: Flow chart for the local processing of shea butter oil (Babatunde and Olaoye,

1997)

Storage

Parboiling and cleaning

Sun drying

Cleaning

Decorticating (cracking on separation)

Enhanced drying by heating (Roasting)

Size reduction (Beating)

Mixing

Size reduction (wet milling)

Extraction by cooking

Clear shea butter oil collected

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Harvested Fresh fruit

Figure 2: Modified and proposed flow chart for the extraction of shea butter oil

(Babatunde and Olaoye, 1997)

Sterilization

Digesting and washing

Sun drying

Decorticating (cracking and separation)

Size reduction (Beating and

Milling)

Clarification

Clear shea butter oil

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Figure 3: Shea tree

Figure 3: Shea nut

Figure 4: Shea kernel

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Figure 5: Shea butter and shea cake obtained from dry extraction at 90 0C

Figure 6: Shea cake obtained from dry extraction at 70 0C

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PROBLEMS OF SHEA BUTTER EXTRACTION

Inefficiency in extraction of shea butter oil constitute to its inability to compare

well with other common vegetable oil (Babatunde and Olaoye, 1997). The factors, which

constitute to the inefficiency in extraction of shea butter, could be from traditional method

or mechanical extraction methods which are explained below.

Problems of traditional method of extraction

The factors which constitute to the in efficiency in the extraction of shea butter are

as follows: -Mesocarp removal, Drying, Shelling, Winnowing, Crushing, Mixing and

Temperature control

Mesocarp removal

The freshly fruits are heaped up for some days until the mesocarp softens by

decay. After this, the harvested berries are crushed underfoot to remove the pulp. This

task is a very slow and tedious task. It requires more people much labour for the exercise

to be carried out.

Drying

Drying is done with the aid of sun by spreading the material on the mat under the

sun and since the supply of it is not specific, we cannot rely on sun for efficient

production and since this is the method employed in the traditional production of shea

butter, it will always constitute inefficiency in production.

Shelling

Traditional method of shelling employ the use of stones, hammer of pestle which

is arduous and time consuming some of the available manual tool are performing below

expectation.

Winnowing

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This task requires the use of basket to blow away the piece of shell that has been

broken down. This task requires winds to blow away the pieces of shell and wind supply

is not specific hence it would definitely affect the efficiency of shea butter production.

Crushing

Crushing is being achieved in traditional processing with mortar and pestles,

which is slow, tedious, energy sapping, arduous and grossly inefficient.

Mixing

The traditional mixing process is carried out inside large pot, strong enough to

withstand the effect of the mixing operation. The mixing is done by hand until it starts to

cover itself with white emulsion of fat. This task is also arduous and time consuming.

Temperature control

Shea butter solidifies at room temperature and hence it should be extracted at a

temperature above the melting point, which might be too hot for the traditional manual

method of mixing using bare hand.

Problems of mechanical expression method of extraction

Despite the fact that mechanical means could be employed in the extraction of

shea butter, there are still some operation which has to be done manually and still affect

the efficiency of production. Operations like collection of fruits from the field,

fermentation of the fruit, crushing, shelling, winnowing and mixing are still being

manually done because their has not been any improved method for carrying out those

operation.

Although, the mechanical extraction is more efficient, alleviate a time consuming

process and improve the time output, the equipment are expensive and scarce and cannot

13

be affordable by most local industries. Other problems associated with the mechanical

extraction process are listed below.

Cracking

Some of the nuts are destroyed during cracking process and this leads to wastage

of raw material for butter extraction. A problem of this nature can discourage the local

women who are the principal stakeholders in the shea butter industry in Nigeria.

Separation

In the process of separating the mixture of nuts and shell, some nuts are lost

during the process, which reduces the quantity of the material and hence caused wastage

of the material.

Roasting

There is insufficient heating of the nuts or too much heating of the nuts.

Insufficient roasting may prevent the oil from attaining the maximum flow during

extraction and at too high a temperature can also reduce the yield of oil.

Cleaning

Cleaning is done by hand-picking and very time consuming. It is necessary to

clean the shea kernel because the presence of dirt like stone can cause wear and tear of the

internal part of the crushing equipment. It can also serve as blockage to the passage of

material in the expeller.

Problem peculiar to shea butter extraction in Nigeria

Water supply

Shea butter extraction requires a lot of water most especially during the mixing of

the paste. One of the problems being faced in Nigeria is water scarcity most especially

during the dry season when there is no rain supply.

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Equipment

Some mechanical assistance which are available in the production of shea butter

can only work on small scale production. The equipment has a very low producing

capacity hence makes large quantity production a difficult task. Also it is not a fully

mechanical procedure but meant to assist the traditional method.

Electricity supply

Operation of the available modern equipment which requires the use of electricity.

The major problem of this oil extraction is on electricity supply, which is not reliable.

Hence operation cannot take place when even there is no supply of electricity.

Maintenance skill

The people involved in the extraction of shea butter in Nigeria are illiterate and

have little or no education about maintenance of this available equipment and this leads to

gradual depreciation of the equipment and eventual brake down. Also the skill to repair

the equipment is not available and hence inefficient production of shea butter.

Supply of lubricants

Constant fuel scarcity and lubricant scarcity is another problem of oil extraction in

Nigeria. The available equipment requires constant lubrication of the rubbing parts and

hence can affect the efficiency of the equipment when not available.

Supply of spare parts

Spare parts for the modern equipment are not readily available and even if it is

available, the people involved in the extraction of shea butter are too poor to afford the

spare parts hence some of the available modern equipment are no longer functioning.

Financial aspect

The people involved in shea butter production are too poor to afford the necessary

things that will improve the production of shea butter and also, they sell the product at a

15

very low price which is not encouraging to go into the mechanical production of shea

butter.

POSSIBLE SOLUTIONS TO THE PROBLEMS OF SHEA BUTTER

EXTRACTION IN AFRICA

Improvement on the method of production of shea butter oil can significantly

improve its quality. Some of the possible solutions that can improve both the traditional

and mechanical methods of extraction are highlighted below

Mesocarp removal

A mechanical stripping system can be developed for the removal of the mesocarp

instead of the time consuming and tedious heaping method to mesocarp to decay. With

the mechanical stripping method, the efficiency in the production of shea butter can be

improved.

Drying

Instead of spreading the shea kernel under the sun which is not specific in supply,

the use of oven or drier can be employed and since the temperature of the drier and oven

can even be controlled, accurate moisture content required for extraction of shea butter

can be obtained and the problem of rain getting the shea kernel wet can be alleviated. The

efficiency in production of shea butter would be achieved due to a less time consuming

task and correct or required moisture content that can be obtained.

Shelling

The use of cracker will reduce time wastage and drudgery, which are encountered

with the use of mortar and pestle. Also there will be reduction in the wastage of the nut

itself. The use of cracker will employ large quantity production of shea butter because

16

large quantity of the nut can be cracked at the same time thereby increasing the quantity

of oil and efficiency in production of shea butter.

Winnowing

Winnowing which is done inside basket with the aid of wind, which is not

specific, can be done with the help of a blower or a pneumatic separator. Due to the

difference in densities of the shell and the nut, the mixture will not reach there terminal

velocity at the same time and hence the separation can be achieved with the use of a

blower or a pneumatic separator. This method is reliable and reduces drudgery and time

consuming task of winnowing.

Crushing

The use of oil expeller can be employed in crushing of shea kernel. The

equipment crushed the shea kernel and press out the shea butter at the same time. This

reduces labour and energy wastage involved in crushing with mortar and pestle.

Mixing

The mixing exercise can be skipped with the use of the oil expeller which presses

out the oil or other wise, the use of mixer can also be employed instead of the tedious and

time consuming mixing task with hand. The mixer can even accommodate much higher

temperature than human hand since the oil is extracted easily at higher temperature.

Temperature control

Shea butter solidifies at a temperature between 34 to 380C hence extracting

temperature of shea butter should be above 380C since extraction is easy at higher

temperature and with this, extraction is hence easier and there is improvement in

efficiency of production of shea butter.

Roasting

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Instead of roasting the shea kernel inside pot on the fire, which is not controllable,

we can employ the use of roaster, which has control, and one can easily get the correct

quality required for shea butter oil extraction and production of shea butter can be done

more efficiently.

Cleaning

Instead of picking the dirt e.g stone with hand, we can use cleaner with

considerable screen the size of the screen being relative to the size of the shea kernel so

that the dirt remain at the top of the screen and then collected while the shea kernel is also

collected at the bottom of the screen.

POSSIBLE SOLUTION TO THE PROBLEM OF SHEA BUTTER EXTRACTION

IN NIGERIA

Water supply

Since shea butter requires a lot of water most especially during mixing of the paste

for the white emulsion to cover the surface, the supply of water should be constant and

since we can not rely on rain supply, other means of getting water supply of water are:

provision of pipe borne water; provision of well at the processing site; provision of

borehole at the processing site; provision of a large reservoir that can store water

rainwater. But for more reliable and less arduous water supply, the bore-hole is more

preferable because the supply from the pipe borne water might not be constant and supply

from well might be arduous.

Equipment

The available mechanical assistance for production of shea butter has a very low

producing capacity and enhances inefficiency in production of shea butter. There is need

18

to employ equipment that has a larger producing capacity so that efficiency in production

of shea butter in Nigeria can also be improved.

The use of mechanical method that would reduce this long process of extraction to

a short process and more oil yield can be obtained. Like they have been able to employ

the use of hydraulic press in Netherlands which is a shorter processed and more efficient.

The use of this kind of equipment can also be employed in Nigeria to improve the

efficiency of shea butter extraction.

Electricity supply

The available mechanical assistance equipment is being powered by electric motor

and supply of electricity in Nigeria is not constant. For efficient production, the use of a

standby generator can be considered so that when supply from NEPA is off, the generator

takes over and interruption in the extraction process cam definitely be eliminated.

Maintenance skill

Most of the people involved in extraction of shea butter lack the maintenance skill

for the available mechanical assistance equipment and solution to this is by training them

on how to maintain this equipment to avoid constant brake down of the equipment for

increase efficiency of production of shea butter.

Supply of Lubricants

Shea butter is very viscous oil which has some lubricating property and instead of

viewing for the scarce lubricant, shea butter can also be used as lubricant in some cases.

This can increase the efficiency of production of shea butter by eliminating problem of

scarcity of lubricant.

Supply of spare parts

Most of the spare parts for the mechanical assistance equipment are scarce and

once there is problem of changing the parts, the equipment becomes down and operation

19

stops. Importation of the spare parts is the solution to this problem or the local industries

should be encouraged in the production of spare parts for this equipment so that it could

be available when needed.

Financial aspect

The people involved in production of shea butter are too poor to afford most of the

above materials needed for the improvement in shea butter production. The government

should intervene in the provision of these materials that are needed for increase efficiency

in production or some individual who can afford the materials should develop interest in

production either by going into production of shea butter or by assisting the people

involved to provide for those materials.

CONCLUSIONS

In the extraction of shea butter, it is very obvious that a lot of problems are

encountered. These problems reduce the efficiency of oil production most especially the

quality and quantity of oil.

It is therefore evident that by solving all these problems, there will be

improvement in the extraction of shea butter and also in the quality and quantity of the

yield. Since shea butter is a very good vegetable oil used for so many purposes,

improvement in the yield and quality will bring about improvement in income for the

people that are involved in this occupation and also more shea butter in the market of

vegetable oil.

RECOMMENDATIONS

A more efficient method of extracting shea butter should be developed by

engineers to reduce drudgery in operation and also to improve the quality and quantity of

oil. Training should be provided and encouraged for the people involved in this extraction

on the use of the equipment and also its maintenance.

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Finally, the government should render the necessary assistance required the

following areas: supporting research and development in terms of funding; upgrading of

the existing sheabutter local cottage; marketing of the finished product; encourage

concerted research effort on shea butter; aAn initiative similar to Cassava, Rice, and

Cocoa should be set up for shea nut and other oil seeds.

.

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