CHAPTER ONE

1.0 INTRODUCTION

In the major world one major source of protein and vegetable oil is from

oil seeds /fruits (Williams M. A. 1996). Oil constitutes a well defined class of

naturally occurring substance. It is greasy being soluble in organic solvents but

insoluble in polar solvents such as water. Oil is a liquid at room temperature.

Commercially oil as well as fats is sourced from certain plant groups mostly

seeds and nuts and some parts of animal within which they occur in relatively

large quantity in an easily available form (McGraw-Hill 1997). The existence

of oil in certain plants has been known for century of years (Ogbu 2005).Oil can

be grouped into edible and non-edible oil depending on the amount of

unsaponified matters and impurities contained therein. Edible oil extracted from

African pear bread fruits cashew nut peanut etc. are examples of vegetable oil

which are naturally occurring esters of higher fatty acids and glycerol and are

predominantly triglycerides with traces of mono and diglycerides sterples anti-

oxidants vitamins saturated and unsaturated free fatty acids and other minor

constituents. They are widely distributed in nature and were first consumed as

food. Later oils were discovered to be used as renewable raw materials for

variety of non-food production. For instance; soaps creams disinfectants

paints enamels inks etc.

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Due to the oil boom in the early 70‟s agriculture was abandoned for petroleum

and its product but recently things are taking a new turn in Nigeria over

dependence on petroleum for virtually everything has not really helped matters.

The economic situation in the country is bad and the general standard of living

is getting poorer with each passing day Hence the need for a restructure of the

economic system with an agricultural bias.

Most agriculture products such as these oils extracted from local seeds and nut

if properly monitored and harvested can be very useful for us down here and

even exported for foreign exchange hence the need for this project which deals

on the extraction and analysis of African pear oil.

Extraction of oil from various vegetable resources is of ancient origin. In fact

the natives from different tropical regions of the globe have long been

extracting oil from numerous oil-bearing plants. Humans since the ancient

times have known how to extract fats and oil from their natural resources.

Historically oils had been extracted by wrapping nuts in clothes and then using

devices operated by stones and levers to exert pressure on them. But now an

improved form of mechanical device which allowed considerably more

pressure to be exerted is now in use in form of hydraulic operated ram. This

type of press is developed into a motorized hydraulic pump system that pressed

the nut bag and then released a pressed cake. The next improvement in

extracting oil is the screw press or expeller which is been driven by electric

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motor.Because most press or expeller processes leads to over-heating of the

meal and leave too- much of the high value oil in cakes better methods of

extracting the oil with solvent was developed. Bush pear was processed by

solvent methods alone in this project. This process can be accomplished by a

variety of ways but as might be expected its efficiency depends to a great

extent on attaining intimate contact between the liquid solvent and the solid

containing the solute. The type of solvent available for this process include n-

hexane petroleum ether benzene n-heptanes acetone etc.

1.1 HISTORICAL BACKGROUND OF THE STUDY

The generic name “Dacryodes” was derived from the Greek word “Dakruon”

meaning [tear] referring to resin droplets on the bank surface of its member

while “Edulis” means edible emphasizing the importance of nutrients fruits in

the plants cultivation .The plant belongs to the family Burseraceae whose

members are characterized by an ovary of 2to 5 cells prominent as inducts in

the bark wood and intrasteminal disk (Chunduff 1984). The genus Dacryodes

consist of about 10 species (Verheji 2002). However (Rehn 1984) indicated 80

species to encompass sub species of varieties form and cultivars. Two varieties

are recognized; Var-parvicarpa and Var-edulis whose conical fruit is smaller

with the pulp. Var-edulis exhibit verticulate or sub-verticulate branching while

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the branching is slender and opposite or bifurcate in var-parvicarpa (Okafor et.al

1983).

Dacryodesedulis is an indigenous fruit in the Gulf of Guinea and central

African countries(Troupin 1950) but due to the popularity of the nutritious

fruit for consumption the plant is widely cultivated extend its area of

distribution to Sierra-Leone Uganda Angola Zimbabwe and Nigeria. It rarely

grows wild thus the natural area of distribution is obscure (verheji2002). Lam

gave four synonyms viz to the Dacryodesedulis :CarnaruimedulieHook.f

CarnaruimsaphuEngl Pachylobusedulis (G.don) Hook. F. and

PachylobussaphuEngl (Burkill 1985National research council1996).

However these synonyms have long been considered as the most unambiguous

synonyms (Boutelje1980).The common names are in English African pear

African pear tree Bush butter Bush butter tree Bush fruit tree Eben tree

Native pear (Kapseu and Tchiegang 1996) and in French Safoutier (Burkill

1985). The oil of fruits of DacryodesEdulis is a rich source of amino acids and

triglycerides. The fatty acid composition of fruit pulp oil of two cultivars of

bush pear [cultivar1 and cultivar2] grown in Nigeria were determined. The oil is

found in the pulp which is made up of 48% of oil and a plantation can produce

7.8 tons of oil per hectare. It is also rich in vitamins and a rich source of amino

acids triglycerides (Derbyshire.et al 1976).

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Bush pear oil is one of the most important rated versatile vegetable oil. This is

due to its uses in various spheres of life most especially as a very healthy food

ingredient.

1.2 AIMS AND OBJECTIVES

This project is aimed at the analysis of bush pear and its oil.The main objective

of this study is to carry out proximate analysis and physio-chemical properties

of African pear oil extracted by solvent methods. This physio-chemical

properties determined are specific gravity refractive index ph value boiling

point acid value iodine value peroxide value and saponification value. To

achieve the objectives of this project it is important to:-

a) Select the best suited solvent for optimum yield.

b) Characterize the extracted oil for compositions and properties.

c) Test the suitability of the oil.

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1.3 STATEMENT OF THE PROBLEM

This research work involves the analysis of African pear and its oil though the

food crop African pear potential is rated one of the highest oil producing fruit

crop yet it begs the question of its potential.

Furthermore this project will answer the following questions;

i) Solvent extraction by solvent method

ii) What is the optimum yield of the particle size using n- hexane?

iii) Is there significant difference in the characterization of the extracted oil as

compared to theoretical value in terms of;

1) Chemical properties (Acid value iodine value saponification value and

peroxide value).

2) Physical properties (specific gravity density viscosity refractive index).

3) Chemical composition (protein crude fibre carbohydrate and moisture.

1.4 SIGNIFICANCE/ECONOMIC IMPORTANCE OF THE STUDY

Characterizing the potentials of African pear/African pear oil for many

purposes has several implications. Communities in the West African countries

are significantly dependent on financial gain from agrarian enterprise.

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It is hope that from the project optimum extraction parameters which are

quality of the oil would be established the result would add to the data bank

that could help potential industrialist who intends to go into vegetable table oil

production from African pear. A crop that experiences a post harvest loss in

excess of 40% in areas where malnutrition is prevalent is a problem for

potentials to reclaim the lost percentage of either food or other purposes is

advantageous for producers and consumers alike.

Furthermore the development of crops with indigenous appeal can

strengthen the agricultural and energy sectors of struggling economics

identifying the oils fuels quantities whether favorable or not will help to

inform future crop and industry development.

1.5 SCOPE AND LIMITATION OF THE STUDY

In this project work we intend to analyze and extract completely African pear

and its oil. Many research work has been done in giving a detailed composition

found in African pear. But this research account on the optimum route to:

i) Extraction of vegetable oil from bush pear.

ii) Separation of pure oil from the solvent.

iii) Characterization of the African pear.

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iv) Characterization of the oil extracted.

Due to the low yield of the above method (mechanical method) of extraction

soxhlet and cold method of extraction are used i.e. solvent extraction.

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