Antioxidant properties of lipoic and dihydrolipoic acid in vegetable oils and lard

Abstract

The properties of lipoic and dihydrolipoic acid in lard and various vegetable oils were investigated as regards their use as antioxidants in food. The measurements were taken by automated Swift-test (Rancimat). Lipoic acid as well as dihydrolipoic acid proved to be antioxidants, although prooxidant effects occurred in low concentrations. The antioxidant effect increased with rising concentration. Fats containing lower levels of polyunsaturated fatty acids were better stabilized than those containing high levels. Mixtures of ascorbyl palmitate with lipoic acid or dihydrolipoic acid were more effective than the separate acids. There were additive as well as synergistic effects. The antioxidant effect of ascorbyl palmitate limited by solubility could be increased considerably by combining it with lipoic or dihydrolipoic acid.