Effect of Heating on the Chemical Composition and Physico - Chemical Properties of Arachis hypogea (Groundnut) Seed Flour and Oil

Abstract

Groundnut (Arachis hypogea) seeds (raw, sun-dried and roasted) were analyzed for proximate composition and some nutritionally valuable minerals. The oil extracted from the samples was subjected to physico-chemical analysis. The results showed that the raw, sun-dried and roasted seeds contained 46.10%, 43.80%, 40.60% fat, 24.70%, 21.80%, 18.40% crude protein, 17.41%, 27.19%, 36.11% carbohydrate, 7.48%, 3.40%, 1.07% Moisture, 2.83%, 2.43%, 2.41% crude fibre and 1.48%, 1.38%, 1.41% ash respectively. There was a general decrease in the proximate composition after exposure to different heating methods but there was variation in the mineral contents of the seeds after heating. Minerals included; sodium (0.71%, 0.69%, 0.57%), phosphorus (0.68%, 0.65%, 0.69%). potassium (0.47%, 0.51%, 0.55%), zinc (0.44%, 0.42%, 0.50%), Iron (0.40%, 0.47%, 0.43%). The physico-chemical properties showed; saponification values of the raw, sun-dried and roasted groundnut oil, 201,195 and 170mg/kOH/g respectively. iodine value, 110.7, 108.5, 100.7 wijs, free fatty acid 1.180, 0.891, 1.260g/100g, acid value 2.35, 1.79, 2.52mg/kOH/g, peroxide value 0.740, 0.603, 0.470 meq/ kOH, refractive index 0.247, 0.256, 0.147. The roasted groundnut can be considered as a good source of valuable minerals, while the raw groundnut is a good source of protein with high nutrition value.