Abstract

Bioactive compounds found in peanut skin (PS), pomegranate peels (PP) and olive pomace (OP) cake were extracted using ethanol (80%), ethyl acetate and hexane. The ethanol extract showed slightly better antioxidant characteristics than ethyl acetate and hexane extracts. Extracts showed varying degrees of antioxidant potential in different test systems in a dose-dependent manner. In general, it was observed that extracts with higher antioxidant capacity were in parallel to their higher phenolic contents. Total phenolic compounds (as gallic acid equivalent, GAE) ranged between 0.89 to 16.6, 1.83 to 261 and 1.56 to 124 mg  GAE/g extract for OP, PS and PP, respectively. Ethanol extracts of different by-products were added to ghee at concentrations of 200, 400 and 600 ppm, respectively. BHA was also added to ghee at a concentration of 200 ppm. All samples were incubated at 63°C/21days. Ethanol extracts of PS, OP and PP gave good antioxidant activity during accelerated oxidative incubation of ghee. It could be concluded that ethanol extracts under study, at a concentration of 200 ppm, can retard fat auto-oxidation.

Key words: Ghee, agri industrial by-products, natural antioxidants, stability indices.