ajayi adebayo ebenezer...research project

8/11/2019 Ajayi Adebayo Ebenezer...Research Project

1/99

1

CHAPTER ONE

INTRODUCTION

1.1

Research background

Shea butter is a versatile plant fat extracted from kernels of shea nuts, seeds of shea trees

(Vitellaria paradoxa). Shea butter has long been used in sub-Saharan Africa for medicinal,

culinary, and other applications and serves as a cocoa butter equivalent in the manufacture of

chocolate as well as an ingredient in cosmetics[1].Shea butter is a slightly yellowish or ivory-

colored fat. It is widely used in cosmetics as a moisturizer, salve or lotion. Shea butter is

edible and is used in food preparation in Africa Occasionally the chocolate industry uses

Shea butter mixed with other oils, as a substitute for cocoa butter, although the taste is

different.Shea butter extract is a complex fat that contains, besides many nonsaponifiable

components (substances that cannot be fully converted into soap by treatment with alkali),

the following fatty acids:oleic acid (40-60%), stearic acid (20-50%), linoleic acid (3-11%),

palmitic acid (2-9%), linolenic acid(


2/99

2

Consequently, traditional shea butter has to be purified (or refined) in order to mitigate these

components and its overall quality with the least damage to the triacylglygerol [4].

Considering countries like Malaysia who have attained an economic upliftment through

theplantation and processing of palm oil. Nigeria has a chance to boost her economy

bymaximally exploiting other of her resources apart from petroleum. One of these resources

is shea butter.For industrial processors, Shea has been relegated to a low cost substitute

product, but as withtrue Cinderella commodities, there is a glimmering interest from the high

value niche markets forgreater use of Shea. Currently, Shea is undergoing renewed demand

from the high valuecosmetics companies and for this market sector, the very fact that Shea

remains a wildernesscrop that it is produced naturally, that it has cultural and medicinal

qualities and is collected andprocessed by womens groups in remote rural areas, all combine

to create a fashionablemarketing scenario for high profile cosmetics products.

1.2Problem statement

Traditionally, in West Africa, processi6f shea butter were practiced by the collectors of the

69shea nuts by persons using their own approach and methods. Local production of shea

butter revealed problems which include the inconsistent product and the difficulty to control

or procure consistent product due to the lack of quality control and the varied and degraded

quality shea butter. Shea butter, especially, undergoes hydrolytic and oxidative degradationsduring the post-harvest processing and storage, which results in the shea butter characterized

by high values of free fatty acids and peroxide values. All these factors lead to inconsistency

of quality and limited shelf-life of shea butter. Hence this research work is necessary so as to

provide a mechanical way of extracting shea butter and to assess an increase in the quality of

shea butter produced.

1.3 Aims and objectives of the study

Consequently, the aim of this work is to develop a mechanical process to extract shea butter.

It is anticipated that the mechanized extraction process will lead to:

1. Improving the appearance and acceptability of shea butter by its users.

2. Reduced impurities which are usually formed during the traditional production.

3. The development an effective mechanized extraction process for shea butter that is


3/99

3

efficient and can easily be implemented on a small or large scale.

The objective of this work includes;

1. Effect of Temperature of water added to paste

2. Effect of kneading Speed on shea butter yield

3. Effect of kneading time on shea butter yield.

4. Determination of the kneading speed in revolution per minutes.

5. Determination of some physio-chemical properties on the shea butter such as acid

value, saponification value and refractive index.

6. Determination of the composition of fatty acid in the shea butter

1.4 Method and Scope

The method that will be employed in this work is the use of food processor to knead the

shea paste for the extraction of shea butter. This method involves crushing and grinding of

shea nuts, the paste is mixed with water and then kneaded at specific speed and time. Water

is added subsequently, and fat is scooped from the surface of the kneaded paste, the fat is

then boiled, weighed and then analysed. The procedure is repeated at different speed,

temperature and time.

This work is limited to the extraction of shea butter found in Saki, Oyo State Nigeria. Also

other methods of extraction will not be considered due to the time and economic constraints

for this research.

1.5 Relevance of research to the society

The following will be the relevance of this research to the Nigerian society:

To generate employment opportunities for the Nigerian populace.

To increase foreign exchange generation of Nigeria through the exportation of shea butter

to foreign nations.

To serve as a catalyst for the development of a shea butter processing industry in Nigeria.

To serve as a reference material for other studies and advancements in the area of shea

butter extraction in Nigeria.


4/99

4

CHAPTER TWO

LITERATURE REVIEW

2.1 The shea butter tree

The history of the Shea tree,Butyrospermum parkii, is well known and documented in the

Western world since the days of Mungo Park, the British explorer who first described the tree

from his journeys in West Africa in the 18th century. In the semi-arid sub-Saharan region the

Shea tree is a valuable asset, yielding edible oil for domestic use and products for cosmetic and

pharmaceutical uses. It is because of these unique healing properties that the Shea tree got its

name, the karite tree, which means the TREE OF LIFE[5, 6].

Vitellara paradoxa, the Shea butter tree, grows across a wide swathe of Sahelian Africa, from

Senegal to Ethiopia. Throughout, the Shea belt, the trees are highly valued by the local

communities not only for the economic and dietary value of the cooking oil, but also for the fruit

pulp, bark, roots and leaves, which are used in traditional medicines and for the wood and

charcoal, used for building and cooking. European explorers recorded the Shea tree as early as

1728 and first samples were collected by Mungo Park in 1796. It was some 30 years after Parks

expedition to West Africa, that the tree was classified as Vitellaria paradoxaby von Gaertner in

1807. In 1865, the West African tree was re-classified as Butyrospermum parkii, by Theodore

Kotschy, and the East African subspecies was classified as Butyrospermum nilotica[6].

In his journals, Park described the local trade in Shea products as a vibrant inland commercial

activity and since that time agricultural officers posted to Africa have made detailed notes of the

local trade in Shea nuts, butter, oil, cake and latex and also speculated on its export trade

potential. Along with many other oil crops, samples were tested for fuel and food products. By

the 1920s, a flourishing trade was developing between West Africa and Europe where the butter

was used in making vegetable margarine and candles. However, changing agricultural policies inEurope and new product formulations led to a decline in demand for Shea and in many respects

Shea now falls into the Cinderella crop category.

Shea nut (SN) is known as Kandayi, Osisi and Emi among the Hausa, Igbo and Yoruba people of

Nigeria, respectively.Butyrospermum Paradoxum (shea butter tree) is locally abundant in the

middle belt areas (Benue, Kwara,Niger states and Abuja) where it is found growing wild [7]. Shea


5/99

5

butter continues to be used and traded in the Sahel as a source of cooking oil but shea butter is no

longer a mainstream industrial product. Despite interest by Governments and FAO expert panels

to develop local industries on shea butter, no attempts have been made to domesticate the crop

and essentially shea butter remains a wild fruit that is seasonally gathered by the local

community. For industrial processors, shea butter has been relegated to a low cost substitute

product, but as with true Cinderella commodities, there is a glimmering interest from the high

value niche markets for greater use of Shea.

Currently, shea butter is undergoing renewed demand from the high value cosmetics companies

and for this market sector, the very fact that Shea remains a wilderness crop that it is produced

naturally, that it has cultural and medicinal qualities and is collected and processed by womens

groups in remote rural areas, all combine to create a fashionable marketing scenario for high

profile cosmetics products.

The shea tree is such a valuable tree and its various areas of utilization can be shown in the table

below.

Table 2.1: Utilization of the Shea tree [6]

Part of tree

(Vernacular)Recorded use

Fruit Eaten fresh or dried and stores for later use.Also described as a famine food.

Seeds Dried seeds used for oil production or sold

for immediate income

Oil The oil is mainly used as edible oil, forfrying, as an addition to sauces or sold in

local markets as an important source of

income. Other uses include utilization in

many cultural ceremonies (wedding, birth,

naming of new babies, funeral,rain, crop/soil fertility, divining the future

and ordination of local chiefs or priests) andas a preparation for battle. The oil has also

been described as a traditional; moisturizer,

as an ointment for newborn babies, as alubricant of machinery and as an important

component of medicines for sprains, scabies


6/99

6

or as an open wound dressing. The oil/fat can

also be used to produce traditional soap andto protect wood or metal from corrosion.

Wood The wood is used as charcoal or firewoodand the pools are frequently employed as the

roof or Y shaped poles in houseconstruction. The timber is also used forlocal handicrafts (stools, pestles and mortars)

and as beehives. In addition, large tree boles

are used to build local canoes.

Whole tree The whole tree is said to improve soil

fertility, provide shade and protect against

wind or soil erosion.

Leaves Although rarely utilized, the leaves from thistree species are used in funeralceremonies

Flowers The flowers are usedto flavour tobacco, asa medicine to reduce chest pains and to cure

eye problems. They are also know to beimportant in honey

production

Bark Frequently used as a medicine for stomach

problems, specifically against

diarrhoea

Residue The bi-product or residue from oil productionis commonly used as a termicide

for houses (to protect walls and poles) orcrops, burnt to repel mosquitoes and

the ashes from this product can be used to

produce local salt

Latex The latex is used as a medicine to dress open

wounds, as a glue to seal pots or calabashesand as an adhesive to trap animals or birds

Roots The roots are utilized in the production oftraditional medicines.


7/99


8/99

8

Figure 2.1 - Agricultural parkland, with shea trees

Figure 2.2 - Shea fruit

Figure 2.3 - Shea Nut


9/99

9

Figure 2.4 - Shea Butter

2.2.2 Composition of shea butter

Native shea butter consists mainly of triglycerides and a large fraction of unsaponifiable

materials.The fatty acid composition of the triglycerides is dominated by oleic, stearic and

linoleic acids. The unsaponifiable fraction contains high amounts of cinnamic acid esters of

triterpene alcohols but also a smaller fraction of sterols. The most characteristic triterpene

alcohol of shea butter is butyrospermol but other important constituents are lupeol as well as

alpha- and beta-amyrin. Shea butter also contains tocopherols (Vitamin E) functioning as

antioxidants.

2.2.2.1 Free fatty acids

Shea butter is composed of five principal fatty acids: palmitic, stearic, oleic, linoleic, and

arachidic (Table 2.2) [8]. The fatty acid composition is dominated by stearic and oleic acids,

which together account for 85-90% of the fatty acids] .The relative proportions of these two fatty

acids produces differences in shea butter consistency. The high stearic acid content gives the

shea butter its solid consistency, while the percentage of oleic acid influences how soft or hard

the shea butter is.

The proportions of stearic and oleic acids in the shea kernels and butter differ across the

distribution range of the species. Ugandan shea butter has consistently high oleic acid content,

and is liquid at warm ambient temperatures. Ugandan shea butter fractionizes into liquid and

solid phases, and is the source of liquid shea oil. The fatty acid proportion of West African shea

butter is much more variable than Ugandan shea butter; the oleic content ranges from 37 to 55%.

Variability can even be high in relatively small local populations; a tree that produces hard butter


10/99

10

can be located right next to one that produces soft butter. Nuts are gathered from a wide area for

local production, so shea butter consistency is determined by the average fatty acid profile of the

population.

Table 2.2: Fatty acid variation in shea butter [8]

Fatty Acid Percentage of Total fatty acid(%)

Mean Minimum Maximum

Palmitic 4.0 2.6 8.4

Stearic 41.5 25.6 50.2

Oleic 46.4 37.1 62.1

Linoleic 6.6 0.6 10.8

Arachidic 1.3 0.0 3.5

Fatty acid carbon chain length:number of double bonds

N.B. Data are from 432 trees samples in 42 populations in 10 countries [8]

2.2.2.1 Phenolics

Phenolic compounds are known to have antioxidant properties. A recent study characterized

and quantified the most important phenolic compounds in shea butter [9]. This study identified 10

phenolic compounds in shea butter, eight of which are catechins, a family of compounds being

studied for their antioxidant properties. The phenolic profile is similar to that of green tea, and

the total phenolic content of shea butter is comparable to virgin olive oil. Phenolics of shea butter

extracted by traditional methods are usually more than those extracted by hexane. Furthermore,

they note that the catechin content alone of shea kernels is higher than the total phenolic content

of ripe olives.[10].

2.2.2Properties of shea butter

Smell: Shea Butter like all other natural products has a natural scent. These scents do not

stink. The natural scent is usually stronger if the shea butter is fresh. As the Shea Butter

gets older, the natural scent diminishes. Shea Butter with no scent is not unrefined shea


11/99

11

butter. Traditionally extracted or cold pressed shea butter will usually have a nutty and a

slight smoky scent to it because it is prepared under open fire. Once applied to skin or

hair, there is no scent. Unrefined shea butter will not be fragranced.

Shelf-life: This is another area of misunderstanding for some people. Unrefined Shea

Butter does not spoil. Its healing properties are very powerful within the first year and a

half. After that, it is still usable but not as beneficial. There is no need to store it in a

freezer or refrigerator. Treat it like you treat your moisturizers and lotions. Keep it in a

cool dry place. There is no special way to handle it. It just is. If you have ever

encountered spoiled unrefined shea butter, then it was not unrefined shea butter to begin

with.

Texture: The native shea butter is a semi-solid, waxy material which melts at

approximately 30-35C.The texture of shea butter is smooth. Fresh shea butter is usually

very soft. As the shea butter ages, it becomes stiffer but still smooth. Shea Butter is

naturally thick and fatty (in a good way). A little goes a long way. Shea Butter is easily

melted by the hot sun or any form of heat. This will make it liquefy. It will get back to its

solid state once it is in a cool area. When shea butter is melted under direct heat or very

high temperatures, the texture changes. It becomes grainy and never returns to its

original texture. Some processed Shea Butter may have a gummy texture to it.

2.2.4 Importance and uses of shea butter

2.2.4.1 Traditional use of shea butter in Africa

Shea butter has long been used in the West African countries, dating back to ancient Egypt based

on the record that during the Cleopatras Egypt, caravans carried clay jars of valuable shea butter

for cosmetic uses (Goreja, 2004). Many records on traditional uses of shea butter have focused

on its ethno pharmacological uses. Shea butter was used by local healers as a treatment for

rheumatism, inflammation of the nostrils, nasal congestion, leprosy, cough, and minor bone

dislocation[11]. Shea butter has also been used for soothing and accelerating healing after

circumcision, and for preventing stretch marks in African pregnant women (Goreja, 2004),

which is frequently mentioned on the advertisement of shea butter products. Shea butter has also


12/99

12

been used to massage newly born babies. In addition, shea butter has been used as an insect

repellent, providing protection against Simulium infection (Goreja, 2004).

In addition to the ethnopharmacological uses, shea butter has been used in West African cuisine

as edible oil due to its high nutritional value and affordable price[12].Shea butter is used as the

base of many soups and condiments (Goreja, 2004). For example, when shea butter is mixed

with onion and pepper, it becomes a popular condiment. Beverages made with shea butter

combined with millet flour, water, and savory spices have been served during weddings,

funerals, and work parties.

African local communities have also found uses and applications of shea butter for lamp and

heating oils, lubricants, weather-proofing roofs and soap manufacturing. Shea butter, in

addition, has been beneficial for domestic animals as moisturizer which is applied to dogs to

protect their skin and paws against harsh sand and salt.

2.2.4.2 Benefit of using shea butter

Skin, scalp, and hair emollient and moisturizing activity:Due to the semi-solid

characteristics and buttery consistency, shea butter itself can be used as great emollient

and moisturizer without further processing

Anti-aging of skin due to protease-inhibiting activity: Collagen and elastin are the

major structural proteins providing skin with toughness and plumpness and -amyrin and

lupeol, the triterpenes also found in the unsaponifiable fraction of shea butter, were found

to contribute to the inactivation of proteases such as metalloprotease (e.g., collagenase) as

well as serine protease (e.g., elastase)

Sun-screening function: Cinnamate esters oftriterpene alcohol which are the main

constituent of shea butters unsaponifiable fraction are known to have strong absorbance

of UV radiation in the wavelength range at 250-300 nm, which make the addition of shea

butters unsaponifiables into sunscreens provide synergistic sun-protection by increasing

absorption of UVB radiation.

Anti-inflammatory effect:Traditional uses of shea butter in African folk medicine have

been greatly attributed to the anti-inflammatory properties of shea butter, which may be

related to the unsaponifiable fraction, especially triterpene alcohols and phytosterols.

Although, there is a lack of studies using unsaponifiable components (lupeol, -amyrin,


13/99

13

and -amyrin) specifically isolated from shea butter, several studies have focused on the

same components found in other species.

2.3 Shea nut processing

2.3.1 Drying of kernels

After the shea nuts are collected the nuts go through five processing steps before they are

place in storage, put out for sale or before butter can be extracted from them. The process of

obtaining dried kernels is depicted schematically in figure 2.5.

FIGURE 2.5 Steps of processing freshly picked nuts into dried kernels[13]

2.3.1.1 Removal of pulp

After the nuts have been collected, the pulp of the shea fruit is removed. The pulp contains

highamounts of sugar that encourages the growth of fungi which decreases oil content of the

kernel. So the purpose of the removal of pulp is to prevent further growth of fungi.

2.3.1.2 Boiling

After depulping the nuts are boiled to terminate the germination process of the nuts. The

germination process starts within a few days after the nuts have fallen to the ground and leads to

the formation of free fatty acids, which will result in poorer shea butter quality and can cause a

bad taste. After the nuts have been cooked for about 45 minutes ash is added to the nuts.

According to the locals this step stops the formation of starch and is needed to successfully

obtain she abutter later on. The prolonged boiling of the fruits tends to destroy desirable natural

compounds that keep the kernel in good condition. The processors state that boiling for a

prolonged period makes extraction of butter during more difficult or even impossible later on.


14/99

14

2.3.1.3 Drying nuts

When boiling is finished the nuts are left on the ground or on the roof for a couple of days to

dryin the sun. At the end of this drying step, the moisture content of the nuts will be

approximately8% of their weight. Shea can nuts will turn black if the nuts cannot dry well,

forexample if they are wetted by rain or when direct sunlight is not available. Poorly dried or

blacknuts fetch lower prices on the market than well-dried kernels.

2.3.1.4 Removal of shell

The nuts are well-dried when they produce a rattling noise when shaken. At this point, the

shellhas detached from the kernel and the shell can be easily removed by hand after the nut

iscracked. Cracking of the shell is done by gently pounding the nuts with a mortar or stone.

2.3.1.5 Drying kernels

The kernels are then dried for another 3 to 5 days. After this the moisture contents in

kernelsshould be about 1% of their weight. This is done to prevent fungi to grow in the nut.In

table below the results of time of labour and resource costs are shown per processing step.

Thiswas measured during shea nut processing by women in the Kpare community. In table 2.3

anoverview is given on the resources cost, labour time, aim of the step, and tools used

perprocessing step.

1. Time necessary to collect water and firewood is not included

2 .Weather dependent; more sun, less time needed to dry

Once the kernels are dried they are either stored, or they are sold or processed right away.

Generally, shea kernels stored in large plastic sacks inside a storage room. In Ghana there were

two types of standard sized bags which are the one that can contain 120 kg of shea kernels

(40coco bowls1 of kernels), and the smaller bag can contain 90 kg of kernels (30 coco bowls).

During storage the kernels sometimes get infested with fungi. This is the case when the nuts are

not well dried, or when the nuts are stored in humid conditions. To get rid of the fungi the

kernels are washed with fresh water and re-dried for a couple of days. Other problems that occur

during storage are maggots that eat the nuts.


15/99

15

TABLE 2.3 - Schematic overview: processing steps of getting the nuts ready for storage

2.3.2 Shea butter extraction

FIGURE 2.6 - Steps of processing shea kernels into shea butter


16/99

16

2.3.2.1Traditional manual extraction[13]

When the women extract shea butter, a maximum of six to twelve kg of kernels is processed

at a time. This is because some processing steps need to be done on the same day with limited

time intervals, and with too much quantity being processed at the same time, this is not possible.

The processing steps needed for traditional shea butter extraction and that will described in this

section are: 1. breaking 2. roasting, 3. pounding 4. grinding 5. beating and 6. boiling.

A. Breaking

The first step is to is to break the kernels into small pieces so that they are prepared for roasting.

Breaking is done with a mortar and pestle.

FIGURE 2.7Nut crushing

B. Roasting

Then these nut pieces are roasted. After this step it is vital that all the process that follow:

pounding, grinding, beating and boiling are done with limited time intervals. Roasting is stopped

when the kernels attain a deep brown colour and when they can be easily broken by hand.

According to Schreckenberg, roasting at a temperature close to 120C will lead to maximum

butter extraction without the kernel getting burnt. Butter extracted from burned kernel bits will

become black and cant be sold on the market.

FIGURE 2.8Roasting of shea nuts


17/99

17

C. Pounding

Once roasted, pieces are again pounded with a mortar and pestle to obtain a brown-black paste.

The paste is then removed and put in a cooking pot is heated to facilitate the grinding step which

is next.

D. Grinding

The heated black paste is grinded with a grinding stone on a flat stone surface. This step is

indicated by the respondents to be the hardest. This step is a vital part for the butter extraction

process, for the thoroughness at which the grinding is done will be a determinant factor for the

quantity of butter that is eventually obtained.

E. Beating

Before the paste is beaten, warm water is mixed into the paste. Warm water is added several

times during the beating to keep the paste at a relative high temperature because if the paste

becomes too cold the mass becomes though and beating becomes difficult. During the beating

process the butter should appear as a creamy mass floating on top of the mixture, see figure 2.7.

FIGURE 2.9 - Creamy mass separating from brown water

F. Boiling

This mass is then washed once or twice before boiling. Washing will remove unwanted shea nut

and contaminant compounds from the butter, however it also removes vitamins and taste; so too

much washing is undesirable. To obtain the butter the creamy mass is boiled in a cooking pot.


18/99

18

FIGURE 2.10Boiling/dehydration

Due the lower boiling point of water compared to the butter, the water will evaporate leaving the

butter behind. Women remove pot from the fire and wait a few minutes for the oil to cool down

and decant to remove any remaining impurities, leaving a clear yellow oil. After this the oil is

left to cool down, it will turn into a solid white butter. The labour and resource costs for each of

the described steps are shown in table 2.4.

TABLE 2.4: Schematic overview of processing steps butter extraction


19/99

19

2.3.2.2Chemical (solvent) extraction

Shea butter has been extracted from the seeds of the shea tree, B, Parkii, with various organic

solvents. Petroleum ether (40C-60C), n-hexane, chloroform and benzene. These solvents,

particularly petroleum ether and n-hexane, can be used for the production of shea butter that is

free oxidized fat and coloring impurities. It was, therefore, thought desirable to employ the

solvent extraction, method, which can be used to extract the oil at a lower temperature and thus

avoid oxidation of the fat. Petroleum ether and n-hexane extraction will in a lower recovery than

chloroform, but the products were acceptable in comparison with the product obtained by

chloroform extraction [14].

To remove the natural aroma and color, most companies use a chemical called hexane. This

depletes the natural healing properties not to mention that a harmful chemical has been added. It

is not necessary to take off the shea butter aroma and color as Shea butter is non greasy and will

not clog your pores. It is quickly absorbed into your skin within minutes, leaving it non greasyand the earthy aroma disappears soon as it is absorbed by the skin. Most of the fatty contents are

obtained by chemical extraction using hexane as the solvent; it has an advantage of higher

percentage of fatty acid.


20/99

20

2.3.2.3Soxhlet extractor

In this method, seeds of shea butter were packed in soxhlet extraction and extracted with a

solvent until extraction was complete. The solvent was evaporated under reduced pressure to a

constant weight and the extracted fat was weighed. In the case of aqueous extraction, the

powdered seeds are boiled with a suitable quantity of distilled water and the supernatant oil layer

was weighed. Currently, hexane, a solvent obtained from petrochemical sources, is the solvent

used for oil extraction. This solvent can be emitted during extraction and recovery and has been

identified as an air pollutant since it can react with other pollutants to reduce ozone and

photochemical oxidants.

A lot of work has been carried out on analysis of shea butter oil by a number of workers,

primarily because of extensive demandsfor oils both for human consumption and for

industrialapplications; consequently there is an increasing needto search for oils from non-

conventional sources to augmentthe available ones and also to meet specific applications, hence

the soxhlet extractor was used. A typical operation mechanism is as follow; 300 ml of petroleum

ether was poured into a round bottom flask. 10 g of the sample was placed in the thimble and

was inserted in the centre of the extractor. The soxhlet was heated at 40C-60C. When the

solvent was boiling the vapour rose through the vertical tube into the condenser at the top. The

liquid condensate dripped into the filter paper thimble in the centre which contained the solid

sample to be extracted. The extract seeped through the pores of the thimble and filled the siphon

tube, where it flowed back down into the round bottom flask. This was allowed to continue for

30 min. It was then removed from tube, dried in the oven, cooled in the desiccators and weighed

again to determine the amount of oil extracted. Further extraction was carried out at 30 min

intervals until the sample weight at further extraction and previous weight became equal. The

experiment was repeated by placing 5 g of the sample into the thimble again. The weight of oil

extracted was determined for each 30 min internal. At the end of the extraction, the resulting

mixture containing the oil was heated to recover solvent from the oil.

2.3.2.4Screw press

Presses have a number of different designs, which can be grouped into screw or hydraulic

operation. Both types can be manual or motor driven. In all types, a batch of raw material is


21/99

21

placed in a heavy duty perforated metal cage and pressed by the movement of a heavy metal

plunger. The amount of material in the cage varies from 5-30 kg with an average of 20 kg. Layer

plates can be used in larger cages to reduce the thickness of the layer of raw material and speed

up removal of oil. The pressure should be increased slowly to allow time for the oil to escape.

Screw types are more reliable than hydraulic types but are slower and produce less pressure. The

fat is squeezed out of the heated shea-powder under high pressure. For a high amountof fat, a

press capable of at 125bar pressure is required. The fat must then be cleared of allresidues by

bringing it to the boil together with okra, lemon juice and water. To increase the output, the

process can be repeated. The resulting press cake is excellent for use as fuel forovens and

reduces the fuel wood demand. The amount of fat derived is determined by thecondition of the

shea nut. The yield will be greater if the harvest carefully stored andpreserved. Complete

inactivation of enzymes will prevent the formation of free fat acids.

The heating of the powder to between 100 and 120 Centigrade is not difficult but theunassisted

use of the press needs longer to learn. In order to get a maximum pressure of

125 bar a lot of force is required by the user. [15].

2.3.2.5Centrifuge

Typical experimental procedures for the centrifugal extraction of shea butter are as follows;

The system designed was a centrifuge machine. It extracted oil from shea nut paste by

centrifugation. Extraction involved separating oil from the water and from the paste cattle cake.

The moving part of the device was driven by a motor, or by an engine, depending on the

availability and convenience of either. A shaft driven by the motor or engine was equipped at its

other end with a rotating drum. The drum, with a capacity of 10 kg of shea paste, had a rotation

speed of 1,000 rpm. That speed was high enough to separate the three components of the paste,

i.e. the oil, which had the lowest specific mass and floated to the surface, the water which had an

intermediate specific mass, and the cattle cake which was heaviest and moved down to the

bottom of the drum. Two bailing devices fitted inside the drum were used to take off the oil and

then the water from the drum, once separation was considered to be sufficient.

Figure-10 shows three different oil extraction processes. The central part of the diagram (Branch

B) presents the traditional butter extraction method, as already explained. The left-hand part

(Branch A) presents the pressing method, which is currently the most widespread or most


22/99

22

common mechanical extraction method. The centrifugation method (Branch C), which we tested,

is shown on the right-hand side of the diagram. The expected result in all three methods is the

same i.e. they all aim to squeeze the oil from the cells containing it.

The oil of the kernels or nuts is more or less strongly confined in oil cells, depending on the

capillary strength retaining them [16]. All the methods mentioned above are designed to overcome

forces and burst the cells in order to release the oil they contain [17]. That is done by heating,

pressing, or centrifuging i.e. thermal or mechanical processes. The final step, in all the methods,

i.e. once the oil has been released, is to separate the oil from the other components of the initial

paste. The process tested here set out to dilute the shea paste with water to facilitate diffusion of

the oil from the burst cells into the water. Several types of treatment were tested prior to

centrifugation, the goal being to expel oil from the cells into the water [18]. Each operation, such

as churning, heating or centrifuging, needed to keep the oil clean and clear, meaning that, after

treatment, the oil should display low oxidization and low acidity, a low moisture content, and a

low solid matter content.


23/99

23

FIGURE 2:11. Shea butter extraction diagram: (A) manual press, (B) traditional, (C)Centrifugation.

2.3.2.6 Food processor/dough kneader as a substitute for mixing and kneading steps

In order to improve the quality of the shea butter extraction, new processing technologies has

been introduced. This includes triage (removing germinated, shrunken and insect damaged

kernels), a machine grinder and a hand power mixer. A food processor is a kitchen appliance

used to facilitate various repetitive tasks in the process of preparation of food. Today, the term

almost always refers to an electric-motor-driven appliance, although there are some manual

devices also referred to as "food processors. Foodprocessors are similar to blenders in many

ways. The primary difference is that food processors use interchangeable blades and disks

(attachments) instead of a fixed blade. Also, their bowls are wider and shorter, a more

appropriate shape for the solid or semi-solid foods usually worked in a food processor. Usually,


24/99


25/99

25

Presence of significant fraction (3-12% of total butter) includes many bioactive chemicals

e.g. triterpene alcohols, phenols, sterols & karitene.

2.4.2 Impurities

Filtering ensures the removal of fine particles, resulting from extraction methods, but

leaves the chemical benefits intact

The texture ofpure, or virgin sheabutter can be changed by re-melting & stirring

frequently to prevent crystallization while the butter solidifies

Avoid contamination with iron & water

2.4.3 Scent

The strange but characteristic shea butter smell or scent (combinations of musty,

smoky, vaguely fishy-metallic fragrances) are due to traditional processing methods

&research is in progress to prevent or reduce their prevalence

Shea kernel quality is primary determinant of butter quality including scent.

Therefore those supplying the US need close links to the actual pickers, & first stage

processors, of shea nuts.

2.4.4

Shelf-life

With correct storage, high quality traditional shea butter has a shelf life of at least

one year at room temperature (220 C)recommended to keep bulk shea butter In

refrigerated conditions in sealed containers that exclude light (ultra-violet, air &

water that can damage butter & other chemicals)

Final stage of preparing traditional shea butter is to boil the molten-butterall

microorganisms are destroyed & water content is minimized.

2.4.5 Variability

There is a wide natural variation interns of fat profile, melting point, colour,

unsaponifiable composition, etc, for shea butter of different provenances(source

location). Mixing fats & oils from different shea varieties maybe useful for adjusting

melting-point. R&D is in progress is identify & quantify natural variability.


26/99

26

2.5 Factorial experimental design[20]

2.5.1 Introduction

Factorial experiments are experiments that investigate the effects of two or more factors or

input parameters on the output response of a process. Factorial experiment design or simply

factorial design is a systematic method for formulating steps needed successfully implement

a factorial experiment. Estimating the effects of various factors in the output of a process

with a minimal number of observations is crucial to being able to optimize the output of the

process.

In a factorial experiment, the effects of varying the levels of the various factors affecting

the process output are investigated. Each complete trial or replication of the experiment

takes into account all the possible combinations of the varying levels of these factors.

Effective factorial design ensures that the least number of experiment runs are conducted to

generate the maximum amount of information about how input variables affect the output of

a process.

2.5.2Experiments with factors each at two levels

The simplest of the symmetrical factorial experiments are the experiments with each of

thefactors at 2 levels. If there are n factors each at 2 levels, it is called as a 2

nfactorial where

the power stands for the number of factors and the base the level of each factor.

Consider the case of 3 factors A, B, C each at two levels (0 and 1) i.e. 23 factorial experiments.

TABLE 2.5 Two-level 3-factor full-factorial experiment patterns

RUN A B C AB AC BC ABC YIELD

1 - - - + + + - Y1

2 + - - - + + Y2

3 - + - - + - + Y3

4 + + - + - - - Y4

5 - - + + - - + Y5

6 + - + - + - - Y6


27/99

27

7 - + + - _ + - Y7

8 + + + + + + + Y8

EFFECT

CALCULATION

A= (Y+)/4 -(Y-)/4

The result is then presented on an absolute value of table in order to determine the major

factor affecting the process.

2.6

Economic analysis for developing an improved shea butter industry.Since labour is underutilized in the improved shea butter processing technology (ISBPT) and

bridge press (BP) methods, more of the effort of the existing labour should be tapped to

enable efficient allocation of labour input. Labour use in the case of the traditional method

should be reduced to allow for efficient resource use. In the case of capital, capital

expenditure should be reduced under the traditional and ISBPT methods for efficient

resource allocation. The BP method is allocatively efficient in the use of capital. To enhance

the adoption of the improvedmethod of processing, limiting factors such as high cost of

processing equipment and lack of access to credit, lack of access to improved equipment,

high maintenance cost, lack of awareness on the improved methods and the poor quality of

butter produced in the BP method must be addressed. These factors could be addressed

A, B and C all three at first level

A at second level and B and C at first level

A and C both at first level and B at second level

A and B both at second level and C is at first level.

A and B both at first level and C at second level.

A and C at second level, B at first level

A is at first level and B and C both at second level

A, B and C all the three at second level


28/99

28

through the provision of effective and efficient extension education on the operation of

processing machines, increased access to credit, and the development of more efficient

processing machines at affordable prices.

2.6.1 Nigeria and shea butter

Shea nut has been exported from West Africa to Europe since 18th

century. Shea trees have

significant economic value and are assets to Nigerians today. According to FAO statistics,

Nigeria produced 372,000 metric tons of shea nuts in 2004 representing 57.1% of the world

total. However the countrys export of shea nuts for that year amounted to only 880 metric

tons, far below the graduation capacity. Majority of the products are wasted.

2.6.2

The state of shea nut in nigeria

Shea nut trees grow wild in the wet savanna area in the northern, southern guinea zones and

the dry savanna of the Sudan zone. In Nigeria today the trees grows in an extremely wide

area of Niger, Nasarawa, Kebbi, Kwara, Kogi, Oyo, Ondo, katsina, Kaduna, Adamawa,

Taraba, Borno and Sokoto State. 70% quantity of shea nut produced are not collected and

thus laid wasted inside bush/farmlands.


29/99

29

CHAPTER THREE

MATERIALS AND METHODS

In this chapter, the materials and methods used in the experiment are described in appropriate

sections.

3.1Raw materials and reagents

1. Shea butter (crude): The crude shea butter was obtained from an open market in Saki, Oyo

state. Nigeria

2.0.1M Sodium Hydroxide (NaOH).

3. Distilled water.

4. 0.1M Potassium hydroxide(KOH)

5. Methanol

6. Phenolphthalein Indicator.

7. 0.5 M Hydrochloric acid (HCl).

3.2 Instrumenation and equipment

1. Royalty turbo Handmixer

2. Plastic bowls

3. 200ml and 500 ml-Beakers.

4. Mortar Pestle

5. Oven

6. Wet mill

7. Small transparent container for sample

8. Porous bits (broken glass).

9. Weighing Balance.

10. Thermometer

11. Water heater/electric kettle

12. Muslin cloth for sieving.

13. Flat bottom flask.

14. Heating Mantle.


30/99

30

15. Spatula.

16. Aluminum table spoon.

17. NYC-101 Electric Oven.

18. Scer Scientific 300037 Programmable refractometer.

19. Conical Flask.

20. Crystal display of tachometer.

21. Water bath.

22. Reflux Condenser

23. Burette

24. Pipette

25. Stopwatch

3.3Methods

3.3.1 Seed preparation

Seed Cleaning: The Shea nuts were soaked for about 30mins in hot water and washed several

times with clean hot water to get rid of possible surface mould and possible oxidized oil emitted

from bad nuts.

Drying: The kernels were dried under the sun till they were totally dried, this took about 2days,

this dehydrates the wets nuts and exposes the bad ones from the lot. Bad and black nuts are then

separated from the good ones. The kernels were kept in an air-tight plastic container prior to use.

FIGURE 3.1 BLOCK FLOW DIAGRAM OF SEED PREPARATION

SOAKING WITH

HOT WATER

WASHING WITH

HOT WATER

DRYING


31/99

31

3.3.2 Traditional method upgrade

FIGURE 3.2 BLOCK FLOW DIAGRAM OF TRADITIONAL UPGRADE PROCESS

Nut crushing: The selected nuts are then broken into smaller portions by mortar and pestle

making them ideal for the oven.

Roasting of crushed nuts: The crushed nuts are sent to the oven immediately after crushing and

roasted at 105-115C for30mins.

FIGURE 3.3Electric Oven

NUTS CRUSHING ROASTING OF

CRUSHED NUTS

MILLING OF

ROASTED NUTS

HOT WATER

KNEADING

COLD WATER

KNEADING

COLD WATER

MIXING

COLD WATER

SEPARATION

SCOOPING OF

FAT

BOILING OF FAT

FILTRATION OF

OIL

SOLIDIFICATION


32/99

32

Nut Crushing: The roasted Shea nuts are allowed to cool down for at least 10 minutes and at

most 30 minutes, before being milled in a milling machine into a fine paste.

Cold water kneading: Mixing continues and small amount of coldwater added from time to

time to get a smoother texture. This vigorous mixing breaks the emulsion, causing the fat to

break away from the cake.

FIGURE 3.4 Hand mixer

Hot water kneading: When the fat begins to break away from the cake (this is indicated by the

colour of the mixture from chocolate to milk chocolate), hot water is added to the paste to melt

the fat and set it free from the cake. This important step facilitates the separation.

FIGURE 3.5 Electric Water bath

Cold water separation: Large amount of coldwater is then poured on the mixture and stirred

continuously causing a grey, oily scum to rise. As the stirring continues, more fat is washed and

forced to float on the cold water that separates it from the cake, which now begins to settle at the

bottom of the rubber bowl. Hence the fat was gathered from the surface.


33/99

33

Scooping of fat:The fat was collected from the surface of the cake with a flat metal spoon.

Boiling of fat: Boiling dehydrates the fat completely. It also clarifies the oil/butter as last cake

residues are fried and settle under the pot.

FIGURE 3.6Heating mantle

Filtration and solidification:The oil was filtered using a muslin cloth and then allowed to

solidify by putting it in the refrigerator.

3.3.2.1Experiment 1

Determining the major factor affecting the production of shea butter

The factor was determined by using a factorial experimental design, hence the experiment was

ran 8 times (23) at different conditionsand was repeated again.

Experimental Run 1

300g of Shea butter was weighed into the Hand Mixer.

Kneading was started at the lowest speed of kneading blade i.e (speed1 for

2minutes) with 2 minutes interval rest after kneading to avoid overheating in the

motor of the kneader.

After the first rest, 50ml of water at room temperature was added to the paste.


34/99

34

Subsequent kneading was done at speed 3 for 7minutes with 2 minutes interval

rest after kneading to avoid overheating in the motor of the kneader

Water at 35C was added at a volume of 100ml at two different times after the

second rest.

The last 2 cycles are done for 8 minutes instead of the initial 7 minutes.

The total time for the experimental run was 30minutes.

2000ml of water at room temperature was added and then the fat was scooped

from the surface of the kneaded mixture with a flat metal spoon.

The fat was then boiled until all the water present had evaporated and the residue

shea cake had been fixed in the oil.

The hot oil was allowed to cool and then sieved through a muslin cloth. The

filtered oil was then weighed and refrigerated till analysis was to be carried out.

The yield of the oil in percentage was evaluated.

Experimental Run 2









second rest.








35/99

35




Experimental Run 3





After the second and third rest, 50ml of water at room temperature was added to

the paste.



Water at 35C was added at a volume of 100ml after the fourth and fifthrest.










Experimental Run 4






the paste.


36/99

36



Water at 45C was added at a volume of 100ml after the fourth and fifth rest.










Experimental Run 5









second rest.










37/99

37


Experimental Run 6









second rest.










Experimental Run 7






the paste.




38/99

38











Experimental Run 8






the paste.














39/99

39

3.3.2.2Experiment 2

Determination of the effect of speed of kneading blade on yield.

The shea paste is prepared as shown in the block diagram of traditional upgrade process.

Experimental Run









second rest.










This procedure was repeated using kneading speed 3, 4, 5.

3.3.2.3Experiment 3

Determination of the effect of time of kneading on yield.

The shea paste is prepared as shown in the block diagram of traditional upgrade process.


40/99

40

Experimental Run

The experiment was carried out as experiment 3.3.2.2 using speed 5 and

temperature of water added at 45C for total kneading periods of 45minutes and

30minutes and 20minutes each.

3.3.2.4Experiment 4

Examining the effect of roasting on yield.

A sample of the cleaned dried kernels was wet-milled without roasting.

Experimental Run

The experiment was carried out as experiment 3.3.2.2 for a total kneading period

30minutes.

3.3.3 Determination of the physio-chemical properties

Shea butter samples from traditional upgrade was analyzed and the following analyses was

carried out

3.3.3.1 Acid value

Acid value (or "neutralization number" or "acid number" or "acidity") is the mass of potassium

hydroxide (KOH) in milligrams that is required to neutralize one gram of chemical substance.

The acid number is a measure of the amount of carboxylic acid groups in a chemical compound,

such as a fatty acid, or in a mixture of compounds. In a typical procedure, a known amount of

sample dissolved in organic solvent is titrated with a solution of potassium hydroxide with

known concentration and with phenolphthalein as a color indicator.


41/99

41

Procedure:

I. 10.0g of the oil sample was weighed into 250ml conical flask.95% alcohol (neutral

alcohol) was prepared by diluting methanol with sodium hydroxide (5ml NaOH + 95ml

ethanol= 100ml neutral alcohol).

II. 50ml of neutral alcohol and 50ml benzene were added to the oil in the flask. The contents

of the flask were shaken well to dissolve.

III. The contents of the flask were shaken well to dissolve. The contents were then titrated

against 0.1Npotassium hydroxide solution using phenolphthalein as indicator.

IV. The end point was the appearance of a pale permanent pink colour and the titre value

were recorded.

The acid value is calculated mathematically as:

Acid Value =

(3.1)

Where,

X = volume of KOH required to neutralize the solution (ml)

M1= strength of KOH

W1= weight of oil used (g)

The number 56.1 is the atomic weight of potassium hydroxide (KOH)

3.3.3.2 Refractive index

The refractive index of a substance measures how the substance affects light traveling through it.

It is equal to the speed of light in a vacuum divided by the speed of light in that substance. When

light travels between two materials with different refractive indexes, it bends at the boundary

between them.

The refractive index test was carried out using a programmable refractometer.

Procedure:

I. The apparatus is firstly standardized using pure distilled water whose refractive index at

200C is 1.3330.


42/99

42

II. A drop of the sample was inserted into the machine. After about 1-2 minute(s) the

machine read off the refractive index in Brix scale and the temperature at which the

refractive index was taken.

III. The actual refractive index was gotten by converting from Brix scale to normal refractive

index using conversion tables.

FIGURE 3.3 REFRACTOMETER

3.3.3.3 Saponification value

Saponification value is the number of mg of potassium hydroxide (KOH) required to saponify

the esters in 1g of a sample; and to neutralize the free acids. It also indicates the amount of

average molecular weight of triglycerides contained in the oil.

Procedure:

I. 1 gram of oil was weighed into 250ml dry round bottom flask.

II. 50ml of 0.5ml alcoholic potassium hydroxide was added to the oil. Porous bits were

added to ensure uniform heating.

III. The reflux condenser was setup and the contents of the round bottom flask was refluxed

for about 1 hr. after refluxing the mixture is allowed to cool and is then titrated against

standard hydrochloric acid and the titre values are recorded. Similarly,

IV. 50ml of the same alcoholic KOH, blank (no oil added) was refluxed in a round bottom

flask for 1hr, cooled and titrated against standard 0.5N HCL.

V. The titre value was recorded and the titre value gotten was then used to determine the

saponification value.

The saponification value is calculated mathematically as:

Saponification Value =

(3.2)


43/99

43

Where,

Z = volume of HCL required to neutralize excess alkali (ml)

Z = (XY) ml

X = titer value of HCL against oil and KOH after reflux (ml)

Y = titer value of HCL against KOH alone after reflux (ml)

M1= strength of HCL

W1= weight of oil used (g)

The number 56.1 is the atomic weight of potassium hydroxide (KOH)

3.3.3.4 Ester value

Ester value was obtained by subtracting the acid value from the saponification value. Ester value

represents the number of milligrams of potassium hydroxide required tosaponify the esters

present in 1g of the oil.

3.3.3.5Specific gravity

The Specific Gravity - SG- is a dimensionless unit defined as the ratio of density of the shea

butter oil to the density of water at a specified temperature. This was done by measuring the

density of shea butter oil in reference to the density of distilled water at 20C

3.3.4 GC Analysis of fatty acid composition

3.3.4.1 Transesterification of fatty acids to fatty acid methyl esters (fames)

0.5 g of homogenized shea butter was refluxed with 5 mL of 0.5 N potassium hydroxide

methanolic solution for 5 minutes. After the reflux, 15 mL of ammonium chloride and sulfuric

acid in methanol solution was added and heated for 3 minutes and after the mixture cooled down,

10mL of hexane was added and a solvent fraction was recovered using separating funnel. Then

1.5 mL of the solvent fraction containing fatty acid methyl esters (FAMEs) was dried over

sodium sulfate, and centrifuged at 13000 rpm for 5 minutes. After the centrifugation, the

resultant solution was subjected to GC analysis.


44/99

44

3.3.4.2 Identification of (FAMES) using gas chromatography with flame ionization

detector (GC-FID)

FAMEs were analyzed on an Econo-Cap EC-WAX Capillary Column (length 30m,

internal diameter 0.25mm, phase Polyethyleneglycol, film 0.25m, Alltech, Deerfield, IL) in an

HP 6890 series gas chromatograph equipped with a flame ionization detector and an automated

injector (Agilent, Wilmington, DE). Samples were injected at an initial oven temperature of 60

C held for 1 minute. Then the column temperature was increased at a rate of 10C / min to 200

C. The injector and the flame ionization detector (FID) temperatures were set to 220 C. Helium

was used as the carrier gas.

Peak identification was performed by comparison of retention times of standard solutions to that

of individual fatty acid standards. Fatty acids were expressed as % of total fatty acids.

3.3.5 Determination of the speed in revolution per minute of the kneading blade.

This was done to know the actual rotational speed of the kneading blade; the different rotational

speeds of the processor are indicated as 1,2,3,4 and 5 on the food processor.

The speed of the kneading blade was measured by using photo/contact tachometer. The speed

had to be determined by measuring the speed levels from 1-5. This was done by contacting the

tachometer at the point of attachment of the kneading blade at a particular sped level and

recording the measured value (the measured value is given on the liquid crystal display of

tachometer). This was done for all speed level.

3.4Safety precautions

All nuts were washed and rinsed several times with clean hot water to get

ridofpossible surface moldand possible oxidized oilemitted from bad nuts.

Zero error of the measuring balance was avoided when measurement was carried out.

The shea nut paste was milled in batches in order to avoid the surface area of the

paste from been exposed.

The kneading time operation was properly monitored using a digital stopwatch in

order to ensure accuracy.


45/99

45

Special care was taken with heat source (oven and heating mantle) to avoid all unsafe

conditions.

During the experiment, all fans were switched off to avoid inaccuracy in

measurements.

Clockwise direction was maintained during the kneading process in order to ensure

uniform mixing.


46/99

46

CHAPTER FOUR

RESULTS AND DISCUSSION OF RESULTS

In this chapter the result of the experiments carried out in the laboratory are outlined and

described in various sections.

4.1 Results

4.1.1 Calibration of the speed of the kneading blade in revolution per minute

TABLE 4.1 Kneading speed in revolutions per minute

SELECTOR SPEED ACTION SPEED (RPM)

1 874.9

2 912.3

3 996.9

4 1018

5 1123

4.1.2 Determination of yield of oil

4.1.2.1 Factorial experimental design using manual method

Where A= Temperature (- =35C, + = 45C)

B=Time (- =30mins, + = 45mins)

C= Speed (- =996.9rpm, + = 1123rpm


47/99

47

TABLE 4.2 Manual Factorial experimental results (Detailed calculation is shown in the

appendix C)

MAIN

EFFECTS

INTERACTION

EFFECTS

YIELDIN%

RUN ORDER OFRUN

A B C AB AC BC ABC Y1 Y2

1 7 - - - + + + - 28.7 24.1 26.4

2 3 + - - - - + + 28.8 30 29.4

3 5 - + - - + - + 25.6 23.8 24.7

4 1 + + - + - - - 29.7 30.1 29.9

5 8 - - + + - - + 31.3 28.7 30

6 4 + - + - + - - 33.1 33.7 33.4

7 6 - + + - _ + - 27.3 25.3 26.3

8 2 + + + + + + + 20.1 22.1 21.1

ABSOLUTE VALUE

OF EFFECT

1.6 4.3 0.1 1.6 2.5 3.7 2.7 27.65

From the above result it is shown that factor B which is time produces the greatest effect in the

yield of shea butter. B=4.3.

FIGURE 4.1 Main Effects for shea butter yield (fitted means)

4535

30

29

28

27

26

4530

53

30

29

28

27

26

TEMPERATURE

Mean

TIME

SPEED

Main Effects Plot for YIELD

Fitted Means


48/99

48

FIGURE 4.2 Interaction plot for shea butter yield (fitted means)

4.1.2.2 Factorial experimental design using minitab

TABLE 4.3 Minitab Factorial experimental results

RunOrder PtType Blocks

TEMPERATURE

(C)

TIME

(mins)

SPEED

(rpm) YIELD

1 1 1 35 45 996.9 24.7

2 1 1 45 30 1123 33.4

3 1 1 45 45 1123 21.1

4 1 1 45 30 996.9 29.4

5 1 1 35 45 1123 26.3

6 1 1 45 45 996.9 29.9

7 1 1 35 30 996.9 26.4

8 1 1 35 30 1123 30

4530 53

30.0

27.5

25.0

30.0

27.5

25.0

TEMPERATURE

TIME

SPEED

35

45

TEMPERATURE

30

45

TIME

Interaction Plot for YIELD

Fitted Means


49/99

49

FIGURE 4.3 Pareto Chart of the Effects of shea butter

The uncoded correlation equation from the design software is as follows

Y=583.351-17.5324A-19.4948-0.550357C+0.583872AB+0.0174465AC+0.0189268BC-

0.000570975ABC

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

B BC ABC AC AB A C

EFFECT

TERM

FACTOR NAME

A TEMPERATURE

B TIME

C SPEED

Lenth's PSE= 3.75


50/99

50

4.1.3 Effects of the speed of kneading blade on shea butter yield

TABLE 4.4 Effects of kneading speed on yield (Detailed calculation of yield is shown in the

appendix C)

Temperature = 45C and Time = 30minutes

Speed (RPM) Weight of Oil (grammes) Yield (%) Yield % using

Minitab Equation

ERROR

912.3 60.9 20.3 27.4 7.1

996.9 88.2 29.4 29.4 0

1018 90.3 30.1 31.4 1.3

1123 100.2 33.4 33.4 0

FIGURE 4.4Effects of kneading speed on yield

y = -0.0003x2+ 0.7193x - 367.0121

R = 0.9970

20

22

24

26

28

30

32

34

36

900 950 1000 1050 1100 1150

Y

I

E

L

D

(

%)

SPEED OF KNEADING BLADE (RPM)

TEMP= 45C

TIME=30mins


51/99

51

4.1.4 Effects of kneading time on shea butter yield

TABLE 4.5 Effect of kneading time on yield (Detailed calculation of yield is shown in the

appendix C)

Temperature = 45C and Speed =1123rpm

Time (minutes) Weight of oil (grammes) Yield (%)

45 63.3 21.1

30 100.1 33.4

20 39.6 13.2

FIGURE 4.5Effects of kneading time on yield

y = -0.1136x2+ 7.7x - 95.36

R = 1

10

15

20

25

30

35

40

20 25 30 35 40 45 50

Y

I

E

L

D

(

%)

KNEADING TIME (minutes)

TEMP= 45C

SPEED = 1123rpm


52/99

52

4.1.5 Effects of roasting before kneading on shea butter yield

TABLE 4.6 Effects of roasting on yield (Detailed calculation of yield is shown in the appendixC)

Shea paste Weight of Oil (grammes) Yield (%)

Roasted 100.1 33.4

Unroasted 8.4 2.8

FIGURE 4.6Effects of roasting of shea paste before kneading

4.1.6 Physicochemical properties

0

5

10

15

20

25

30

35

40

ROASTED UNROASTED

Y

I

E

L

D

(

%)

SHEA PASTE

TEMP= 45C

TIME=30mins


53/99

53

TABLE 4.7 Physicochemical properties of Shea butter yield

Oil Sample Acid value Saponification

Value

Ester

Value

Refractive

index

Specific

Gravity@20C

Roasted 12.31 168.3 155.99 1.4666 0.912

Unroasted 5.31 210.38 205.07 1.4660 0.923

4.1.7 Chromatographic analysis of free-fatty acid composition of shea butter

The common names of the some of the components of the shea butter are listed below[22].

n-Hexadecanoic acid = Palmitic acid

Octadec-9-enoic acid = Oleic acid

Trans-13-Octadecanoic acid = Elaidic acid

Octadecanoic acid = Stearic acid

Cis-13- Octadecanoic acid = Linoleic acid

a. Roasted Shea butter sample.

TABLE 4.8Fatty acid variation in Roasted shea butter

Retention time Component Percentage in oil (%)

25.609 Palmitic acid 6.75

29.419 Oleic acid 7.92

29.557 Elaidic acid 16.99


29.974 Stearic acid 13.31


TOTAL 74.08

b. Unroasted shea butter sample

TABLE 4.9Fatty acid variation in unroasted shea butter


54/99

54

Retention time Component Percentage in oil (%)

11.464 5-Tetradecene 2.73

25.448 Palmitic acid 5.94


29.276 Linoleic acid 8.2929.374 Cis-Vaccenic acid 20.42


40.451 Squalene 1.24

TOTAL 92.62

4.2 Discussion of result

4.2.1 Calibration of the speed of the kneading blade in revolution per minute

The various speed of the electric food mixer (i.e 1, 2, 3, 4, 5) was calibrated in

revolutions per minute using a device used for measuring the speed of rotation which is a crystal

display tachometer. And the speeds in revolution per minutes are 874.9, 912.3, 996.9, 1018 and

1123 according to Speed 1, 2, 3, 4, and 5 respectively.

4.2.2 The factorial experimental design for the effects of various factors on the oil yield

In determining the oil yield, a factorial experiment was designed using 8 runs (i.e 23) where the 3

main effects are: (A= temperature), (B= time) and (C=speed) was put into consideration at their

higher and lower values. (i.e temperature - =35 C and 45 C, time - = 30mins, + = 45mins,

speed - = 3, + = 5). The absolute value of effect of all main effects and interaction effects were

determined and the factor B, The time was determined as the major factor affecting the oil yieldwith absolute value of 4.3. Thus increase in time produces a reduction in the yield of shea butter

and also the factors BC (Speed and Time) also had a great effect on the oil yield with absolute

effect of 3.7.


55/99

55

The manual calculation of the factorial experimental results were compared with the factorial

experimental design calculation using a software called minitab, is shown in Table 4.2 and

4.3respectively. Figure 4.1 shows the main effect s plot for the shea butter yield (using a fitted

means). The temperature plot shows that the yield of oil increases as the temperature increases,

while the oil yield decreases as the time increases. Also the yield of oil is virtually independent

of kneading speed.

The interaction plot for the shea butter yield shown in Figure 4.2 which basically compares the

relative strength of the effects across the factors. The first plot which describes the temperature

and time interactions indicates that both extraction time and extraction temperature have similar

effects on the yield of oil .For both factors, the yield decreases with temperature and kneading

time. However the interaction plot shows that the decrease in yield is greater when the time is

high (45mins) than when reaction time is low (30mins). The second plot which describes the

speed and temperature interactions indicates that the reaction speed and temperature have

different effects on the yield of oil. At the lower temperature the oil yield increases as the speed

increases while the higher temperature yield of oil decreases as the speed increases. The third

plot describes the speed and the time interaction. At lower kneading time, the yield of oil

increased with speed of kneading while at higher kneading time, the yield decreased with

increased kneading speed. However the increases in the yield is far greater when the kneading

time is (30mins) than when the kneading time is (45mins).

The pareto chart in figure 4.3 shows the magnitude of the effects of the three factors on the

yield and their respective absolute value. The pareto chart confirms the observation that kneading

time is by far the most important parameter affecting the yield of oil. The effect of other factors;

temperature and speed are much lower. The chart also shows effect of interaction, that is, the

effect of time depends on the level of the kneading rate.

4.2.3 The effects of the speed of kneading blade on shea butter yield.

The effect of the kneading speed on the yield was studied for 30mins, since the yield was

higher at lower kneading period. The results have been illustrated in figure 4.4 and tabulated data


56/99

56

in Table 4.4. The rate of increase in yield is much faster at the lower kneading rate than at higher

kneading speed. Increase in speed of kneading blade leads to increase in oil yield simply because

more vigorous kneading and mixing process helps to break the emulsion quickly, causing the fat

to break away from the shea cake completely[19]

.

4.2.4 The effect of kneading time on shea butter yield

The results have been illustrated in figure 4.5 and tabulated in table 4.5. It was observed that

the yield of oil increased as the kneading time increases from 20 minutes to 30 minutes. This was

so because enough time is required for the fat to break away from the shea cake (which is

indicated by the change in colour of the mixture from chocolate to milky chocolate). It was also

noticed that the yield of oil at kneading time of 45 minutes was lower than that of kneading time

of 30minutes. Longer kneading time resulted in the separated fat remixing with the shea butter

cake. Less fat could be scooped from the surface of shea butter cake as a result of this.

It was observed that the oil yield increases as the kneading time increases from 20

minutes to 30 minutes; this was so because enough time is required for the fat to break away

from the shea cake (which is indicated by the change in colour of the mixture from chocolate to

milky chocolate). It was also noticed that the oil yield at kneading time 45 minutes was lower

than that of kneading time of 30minutes and 20 minutes, this occurred because after the time inwhich the fat had melted (i.e separated from the cake, the fat then begins to mix with the shea

cake, which resulted in the lower amount of fat scooped at time 45 minutes.

4.2.5 The effect of roasting before kneading on shea butter yield

The effect of the roasting of the shea butter variation is clearly shown in Table 4.5. Roasted and

unroasted shea butter has an oil yield of 33.4% and 2.8% respectively. The roasted shea butter

resulted into higher oil yield simply because roasting of shea nut tends to make the fat crystalline

structure loosen for extraction.[24].

4.2.6 Physicochemical properties of shea butter oil

The table below shows the comparison of the physicochemical properties of the roasted

and unroasted shea butter to literature values.


57/99

57

TABLE 4.10 Comparison of Physicochemical properties of shea butter extracted with literature

values extracted

Properties Roasted shea butter Unroasted shea butter Literature value[1]

Acid value 12.31 5.31 0.463-12.59

Refractive index 1.4666 1.4660 1.453-1.6

Saponification Value 168.3 210.38 160-223

Ester value 155.99 205.07 159.537-210.41

Specific gravity 0.912 0.923 0.916-0.917

The acid value of shea butter oil is the mass of KOH in milligrams that is required to

neutralize 1g of the shea butter oil. Basically the acid value is used to quantify the amount of

acid present. Roasting raises the Temperature of the shea butter mix. This decreases the viscosity

of the oil which tends to move towards the surface. Higher temperature tends to break and

destroy the cell during size reduction which tends to increase the acid formation. Hence the rate

of acid formation was higher when the shea butter was roasted. The acid value of roasted and not

roasted shea butter falls within the literature range of acid values as shown in Table 4.10. Hence,roasting of shea nut before milling tends to increase the acid content.

Refractive index is the ratio of the speed of light in a vacuum to that in the oil under

examination which is related to the degree of saturation and the ratio of cis/trans double bonds,

and can also provide hints on the oxidative damage. The refractive index decreased from 1.4666

to 1.4660 for roasted and unroasted shea butter respectively. Basically the refractive index is

used for rapid sorting of fats and oils of suspected adulteration. Hence the refractive index of

roasted shea butter was higher than the unroasted shea butter because the shea butter continues tobe adulterated as the heating temperature increases

[24]. This is due to excessive heating of the

shea nut in the oven. Both refractive index values of the shea butter oil falls within the literature

range of values as shown in Table 4.10.


58/99

58

The saponification value of shea oil is the number of milligrams of KOH or NaOH

required to saponify 1g of shea butter oil. It is a measure of the chain lengths of the fatty acid

presents. The saponification value decreased from 210.38 to 168.3 for unroasted and roasted shea

butter respectively. High saponification value may suggest use of the oil in the soap industry[24]

.

Therefore, the unroasted shea butter oil has a higher chance of being used for the manufacturing

of soap. Both saponification values of the shea butter oil falls within the literature range of

values as shown in Table 4.10.

The Ester values decreased from 205.07 to 155.99 for unroasted and roasted shea butter

respectively. The higher the ester value, the more the palatability of the oil. Hence the unroasted

shea butter oil is more palatable and

ajayi adebayo ebenezer...research project

Documents