EXTRACTION, CHARACTERIZATION AND THERMAL STABILITY STUDIES WITH "Dacryodes Edulis”(AFRICA BUSH PEAR) OIL

Abstract

The need to identify cheaper sources of fats and oils to supplement the nutritional value of the largely carbohydrate based diets in developing countries including Nigeria, motivated the research into the oil quality of African bush pear seed oil this research extend the extraction, characterization and thermal stability studies with African bush pear oil .The African bush pear used in the work was obtained from Ekosodin market, Ugbowo,,Edo state . The extraction was carried out by solvent extraction using N-hexane as solvent. Parameters studies were Acid value,,free fatty acid ,peroxide values, refractive index and measurement of absorbance at 233nm.a wavelength of 675nm. Additionally Fourier transform infrared spectroscopy was used to carry out the spectroscopic studies . All determination were carried out with standard methods and findings indicating the following ;. The yield was 43.3% . The pH for the oil was approximately 5.9 (slightly acidic). The color of the oil of the unheated oil was observed to dark brown while that of the heated was pale yellow. The Uv absorbance of the oil was also found to be 2.005 . However there was significant difference in the values for the heated and unheated seed oil. In parameters like Acid Value measuring 6.1 gm/NaOH/gm for unheated oil with , 4 gm/NaOH/gm( at 60oC) and 3 gm/NaOH/gm( at 80oC ) heated for 7hrs. and Peroxide Value measuring 2gm/NaOH/gm for the unheated oil with 3.3 gm/NaOH/gm(at60oC and 3.7 gm/NaOH/gm( at 60oC ) also heated for 7hrs , refractive index 1.45 for the unheated oil and 1.46 (at 60oC and 80oC ) for the heated oil for 7hrs. From the physcio-chemical analysis of the oil there was an slight increase in the peroxide value and refractive index ,This can reduce the quality of the oil since heating of the oil can easily cause rancidity. But With theses values obtained for the Africa bush pear oil, it can be presumed that the oil will last for a longer period of time during storage. considering the oil yield, African bush pear seed could be exploited for oil and can be use for culinary purpose.