The seeds from this pear were oven dried at 100oC-125oC to a moisture content level of 29%. The seeds were subjected to proximate analysis to determine the percentage of the moisture, fat, crude fibre, crud content which resulted to the values of 29%, 19.6%, 25.5%, respectively. Then the dried sample was pulverized by using grinding 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 8.1gm/KOH/gm, 201.96gm/KOH/gm, 2.5gm/KOH/gm 3.96gm/iodine/gm and Physical properties i.e. ( Ph value, specific gravity) which the values obtained are 5.58 and 0.90. and the The percentage oil yield content is 29.39%. This physio-chemical characteristic and fatty acid composition of this oil show that they have industrial potentials.
1.1 Background of Study
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.
Oil can be extracted from various seeds; however, this work focuses on one particular seeds, (African pear seeds). Extraction can be defined as a separation process consisting in the separation of a substance from a matrix; The first step in obtaining oil from the seed is to remove the seed-coat and husk in a process referred to as dehulling. i separating the chaff and dried by placing the seeds under the sun or by heating carefully on the fire for a short while. In the case of using crude means to extract the oil, drying can be followed by warming which ensures more oil yield. Once this is done, the next step is to begin the crucial extraction process.
These edible oils are consumed in various ways; the liquid form are used for cooking in warmer climate, in the western world, they are eaten in spreadable form,
Dacryodes edulis is cultivated in large quantity in South- Eastern Nigeria and other African countries like Cameroon, Sierra Leone, Uganda, Malaysia, Liberia, and Zaire. There are two varieties of Dacryodes edulis in Nigeria- D.e.var. edulis and D.e.var. parvicarpa (Isaac and Ekpa, 2009). The fruits and seeds of this plant have been found to contain reasonable amounts of oil (Ikhuoria and Maliki, 2007; Arisa and Lazarus, 2008). African pear oil contains the following acids: palmitic acid (9.06%), stearic acid (15.46%), oleic acid (26.63%) and linoleic acid (30.85%) (Ikhuoria and Maliki, 2007) Umoti and Okyi (1987) gave the fatty acid composition and the range of fatty acids in African pear oil as follows: palmitic acid 47.89% (35 – 65%), oleic acid 31.25% (16 – 35%) and linoleic acid 17.5% (14 – 27%). The physicochemical properties of African pear oil determined by Ikhuoria and Maliki (2007) are average melting point (80 0C), refractive index (1.456), viscosity (0.33 poise), free fatty acid (1.100%), saponification value (143.760 mgKOH/g), iodine value (44.079 gI2/100g), acid value (15.280 mgKOH/g), ester value (128.480) and unsaponifiable matter (53.920%). On the other hand, Umoti and Okyi (1987) determined saponification value, iodine value and specific gravity of APO as 201.4 mgKOH/g, 59.6 gI2/100g and 0.9 respectively. Adequate development of this oil could contribute to the nation’s demand for vegetable oils for surface coatings and other industrial applications.
Oils are extracted in two primary ways, by mechanical pressing, or heating and with petroleum solvents. Before the 1940’s, mechanical pressing was the primary method used. Mechanical extraction, however, had its limits in terms of oil recovery. Because pressing generates heat and high temperatures which damage both the oil and meal, an oil content of the press cake below 5-6% was difficult to achieve. Solvent extraction was developed because it allows a more complete extraction at lower temperatures. It begins to be economically attractive where large quantities of seed can be processed (at least 200 tons per day for continuous-feed processes); where storage, transportation, power, water, and solvent supply are adequate; and where occupational safety and training standards can be enforced. This work focuses on the extraction of oil from two local seeds using n-hexane in a soxhlet apparatus, determine the physicochemical properties of the oils based on oil content, pour point, specific gravity, viscosity, refractive index, iodine value, acid value and peroxide value. This study was designed to establish the suitability of the oils for domestic and industrial uses.
1.2 Aim of the Study
The aim of this research is to extract and analyse oil from Dacryode edulis seeds (African pear seeds)
To determine the percentage, yield of oil from the seed
To determine the physiochemical properties of the oil extracted;
To analyze and know the usefulness of the oil extracted
1.3 Statement of the Problem
In Nigeria, it has been estimated product to consumption margin is increasing by thousand tons naturally because of population growth and raise in the use of edible seed oil like coconut etc. For several purposes such as soap making, cosmetics, and other industrial purposes. This situation in particular calls for serious consideration for effective future planning of reducing utilization of edible seed and maximize non edible oil seed production in the country.
Also most edible seeds like pears have been proven to contain reasonable amount of oil which can be applied in so many ways but in Nigeria we love to use oil from coconut. Ways will be discussed in how to extract reasonable amount of oil from African pear seeds
1.4 Justification of Study
The use of edible seed for extraction of oil has been of great concern recently; this is because of the discoveries base on the fact that, they are very important to both human and industrial application. These can cause serious problems if those seeds used are scarce.
Therefore, this research work focus on the use of non-edible seed (African pear) seeds for extraction of oil.