Oxidative stability of ghee as affected by natural antioxidants extracted from food processing wastes

In this research, bioactive compounds found in peanut skins (PS), pomegranate peels (PP) and olive pomace (OP) were extracted using ethanol (80%), ethyl acetate and n-hexane. Ethanol extract showed slightly better antioxidant characteristics compared with ethyl acetate and hexane extracts. Extracts showed varying degrees of antioxidant potential in different test systems in a dose-dependent manner, whereas, antioxidant capacity of extracts was found to be in parallel with their higher phenolic contents. Total phenolic compounds (as gallic acid equivalent) ranged between 0.89 and 16.6, 1.83 and 261, and 1.56 and 124 mg gallic acid/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 for comparison. All samples were incubated at 63 °C for 21 days. Ethanol extracts of PS, OP and PP gave good antioxidant activity during accelerated oxidative incubation of ghee. The results revealed that ethanolic extracts under study, at a concentration of 200 ppm, could be used to retard fat auto-oxidation.