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.
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 n-hexane, petroleum ether, benzene, n-heptanes, acetone etc.