ABSTRACT
The research project studies the analysis of pear and its oil. The mesocarp from
edible African pear “DacryodesEdulis” were evaluated for their oil yield. The
pulp from this pear were oven dried at 100oC-105oC to a moisture content level
of 29%.The mesocarp was subjected to proximate analysis to determine the
percentage of the moisture, ash, fat, crude fibre, crude protein and carbohydrate
content which resulted to the values of 29%, 2%, 19.6%, 25.5%, 11.9%, and
12% respectively. Then the dried sample was pulverized by using hammer mill
and the oil was extracted by solvent extraction using n-hexane. The oil extracted
were analyzed for the chemical properties i.e. (Acid value, saponification value,
peroxide value, iodine value) etc. the values obtained are respectively
8.41gm/KOH/gm, 185.1gm/KOH/gm, 2.8gm/KOH/gm 3.96gm/iodine/gm and
Physical properties i.e. (Refractive index, Ph value, specific gravity) which the
values obtained are 1.469brix, 5.7 and 0.92. and the The percentage oil yield
content is 51.57%. This physio-chemical characteristic and fatty acid
composition of this oil show that they have industrial potentials.
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TABLE OF CONTENTS
Title page i
Certification ii
Approval page iii
Dedication iv
Acknowledgement v
Abstract vi
Table of contents vii
chapter one
1.0 Introduction 1
1.1 Historical background of the study 3
1.2 Aims and objectives 5
1.3 Statement of the problem 6
1.4 Significance/economic importance of the study 6
1.5 Scope and limitation of the study 7
chapter two
2.0 Literature review 9
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2.1 Introduction 9
2.2 Extraction 10
2.2.1 Mechanical/physical method of extraction 11
2.2.2 Chemical/solvent method 12
2.2.3 Basic principles of solvent extraction 13
2.2.4 Choice of solvent/solvent properties 15
2.2.5 Applications of solvent extraction 16
2.2.6 Methods of leaching operations 17
2.2.7 Solvent extraction theory 17
2.2.8 Factors affecting the rate of extraction 20
2.2.9 Properties of solvent 21
2.3.0 Extractors 22
2.3.1 Distillation as a separation technique 24
2.3.2 Classification of oils 25
2.3.3 Properties of oil 26
2.4 African Pear 31
2.4.1 Features of the African pear 31
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2.4.2 Taxonomy of the African pear plant 32
2.4.3 Characteristic and composition of the African 33
2.5.0 Oil from African pear 34
2.5.1 Uses of African pear 35
2.5.2 Economic values of African pear 37
Chapter Three
3.0 Characterisation of dacryodesedulis 40
3.1 Experiment Procedures 40
3.1.1 Material/Equipment 40
3.1.2 Reagents 42
3.2 Pre-treatment processes 43
3.3 Extraction of the oil 44
3.4 Characterisation of the oil. 45
3.4.1 To Determine the percentage yield of the oil 45
3.5 Proximate analysis of dacryodesedulis 46
3.5.1 To determine the moisture contents of the sample 46
3.5.2 To Determine the ash content of the sample 47
x
3.5.3 To determine the fat content of the sample
(lipid – fat & oil) 49
3.5.4 To Determine the crude fibre of the sample 50
3.5.5 To Determine carbohydrate content 52
3.6 Chemical analysis of the oil 52
3.6.1 Determination of acid value of the african pear oil 53
3.6.2 Determination of the iodine value of african pear oil 53
3.6.3: Determination of the peroxide value of african pear oil 56
3.6.4 Determination of saponification value of the oil 58
3.7 Physical analysis of the oil 59
3.7.1 To Determine the refractive index of the oil 59
3.7.2 To Determinethe specific gravity of African pear oil 60
3.7.3 Determination of the ph value of African pear oil 60
Chapter Four
4.0 Experimental results and discussion 62
4.1 Tables and results 62
4.2 Discussion 64
Chapter Five
xi
5.0 Conclusion and recommendation 65
5.1 Conclusion 65
5.2 Recommendation 65
References 67
Appendix 72
1
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, 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.
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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
3
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
4
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 (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).
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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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