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,
antioxidants, 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.
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
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
nhexane, 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
the branching is slender and opposite or bifurcate in var-parvicarpa (Okafor et.al
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 (verheji,2002). Lam
gave four synonyms viz to the Dacryodesedulis :CarnaruimedulieHook.f,
CarnaruimsaphuEngl, Pachylobusedulis (G.don) Hook. F. and
PachylobussaphuEngl (Burkill ,1985,National research council,1996).
However, these synonyms have long been considered as the most unambiguous
synonyms (Boutelje,1980).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).
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
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.
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;