Antioxidant activity,fatty acids and phenolic acids compositions of potato peels

The effects of freeze-dried extracts from the peels of six potato varieties as antioxidants in pure soy oil were investigated using the active oxygen method (AOM) procedure, carotene bleaching and linoleic acid oxidation experiments on thin-layer chromatography (TLC) plates. At 9 h under AOM conditions, 20 g soy oil treated with 0.05 g of these extracts attained lower peroxide values (PV, 22.0-28.0 meq kg^?1) than the control oil sample (PV, 109.0 meq kg^?1) indicating very strong antioxidant activities. Oils treated with the same amount of tertiary butylhydroquinone, butylated hydroxyauisol-butylated hydroxytoluene mixture and rosemary extract attained PV of 10, 19.0 and 16.0 meq kg^?1, respectively. Results of the carotene bleaching and linoleic acid oxidation experiments on TLC plates indicated that the antioxidant activities of these extracts were due to the presence of phenolic acids. Among the phenolic acids separated and identified by both high-performance liquid chromatography and TLC, chlorogenic, proto-catechuic and caffeic acids were predominant and appeared to be mainly responsible for the strong antioxidant activities of the extracts. Peels from the red potatoes contained more polyphenols than those from the brown-skinned varieties, but their oil contents were similar.