PEANUT SKIN ANTIOXIDANTS

Peanut skins isolated from three peanut samples cultivated in China were extracted with hexane, ethyl acetate and methanol. The content of polyphenolic substances was low in hexane extracts, very high in methanolic extracts and intermediate in ethyl acetate extracts. Condensed tannins prevailed in ethyl acetate and methanol extracts, while tocopherols were concentrated in hexane extracts, but only in moderate amounts. The resveratrol content was very low. The antioxidant activity of extracts was rather low in lard and in vegetable oils under conditions of the Schaal oven test, but the free radical-scavenging activity was very pronounced, especially in methanol extracts. The metal-chelating activity could contribute to the antioxidant activity of peanut skin extracts. PRACTICAL APPLICATIONS Peanut skins are waste products from peanut processing. As they are rich in phenolic substances, peanut skin extracts could become a cheap and easily available source of antioxidants, especially their methanol and ethyl acetate extracts. Their activity in lard and other bulk fats is only moderate, but they are efficient free radical scavengers and metal chelators. Therefore, they would be efficient in the stabilization of foods containing water and transient metal ions against autoxidation.