Effect of extraction pretreatment on the composition and characteristics of seed and pulp oil of African black pear (Dacryodes edulis)

Abstract

The effects of pretreatment (roasting, steaming) on yield, composition and characteristics of oil of the seed and pulp of African Black Pear (ABP) were determined. The stability of the extracted oils was also assessed. Roasted samples of seed and pulp gave the highest (p=<0.05) oil yield of 13.01 and 38.53g/100g respectively. The free fatty acid of the seed oil was in the range of 0.93-2.44% mg NaOH/g while that of pulp were between 1.18 and 1.57% mg NaOH/g. The iodine values ranged from 21.00–25.80 for the seed oils and 48.73–49.53 for the pulp oils. Heat treatment decreased (p=<0.05) iodine content, peroxide content and saponification content of both seed and pulp oil samples. Moisture and volatile matter were lowered by heat application while relative densities of oil from all samples were not significantly (p=<0.05) different from each other. Roasting particularly exerted the most considerable effect on the properties including colour and stability of extracted oil of ABP The result obtained corroborate the fact that ABP is a good source of vegetable oil for both domestic and industrial uses. Oil extraction from ABP and subsequent processing and incorporation into commercial oil is recommended so as to boost the valorization and cultivation of this fruit.

Keywords: African black pear, yield, oil extraction, peroxide, free fatty acids

Nigerian Food Journal Vol. 23 2005: 13-20