Preliminary Evaluation of Oils Extracted from Seeds of Under-utilized Tropical Plants

摘要

Oils were extracted from five under-exploited tropical plant seeds,Afzelia bella,Millettia thonningii,Lonchocarpus sericeus,Pterocarpus osun and Etandraphragma angolense and evaluated for the physico-chemical properties.Crude fat and oil content(g/100 g)ranged from 24.9 in A.bella to 51.5 in E.angolense.This value was also high in L sericeus(40.3)and Millettia thonningii(32.3).Oleic,linoleic and linolenic acids were the dominant unsaturated fatty acids,making up to 71.9,72.6 and 73.7% of the total fatty acids in L sericeus,E.angolense and M.thonningii respectively.Free fatty acids(FFA),peroxide values(PV)and acid values(AV)were higher than the recommended limits;this is probably due to the extraction method and storage condition of oil seeds after harvest.Refractive index values were comparable to that of soybean oil,while specific gravities of 0.85-0.95 g cm3,indicate that the oils were denser than most drying oils.High iodine values(121.6-136.4)further indicated the preponderance of unsaturated fatty acids.It was concluded that the oils under study resembled other seed oils that are processed for food use.Considering their high content of oil,there exists a possibility for their commercial exploitation.