Use of ethanol extract of Chuanminshen Violaceum to inhibit the deterioration of frying oil

Abstract

Influence of ethanol extract of Chuanminshen Violaceum (EEC) on the changes in physicochemical characteristics of soybean, rapeseed, and palm oils during frying was investigated. Composition analysis revealed that a total of 16 compounds with possible antioxidant activity were contained in the obtained EEC, such as bergaptol, curcumenol, viscutin, homobutein, nissolicarpin, and 4-hydroxyisopimpinellin. Similar to tert-butylhydroquinone (TBHQ), EEC inhibited the increases in acid value, carbonyl value, and total polar compound content of frying oil during frying. The decrease in content of polyunsaturated fatty acids and the increase in content of saturated fatty acids were also significantly inhibited in TBHQ-added or EEC-added oils. More than 45 % of the reduction in concentration of octanoic acid was obtained in EEC-added oils, which was comparable to those observed in TBHQ-added oils. Thermal oxidative degradation of polyunsaturated fatty acids was proven to be retarded by adding EEC and TBHQ to moderate the deterioration of frying oil. Thus, the potential use of EEC as a natural antioxidant was demonstrated to extend the usage life of vegetable oils with a high content of polyunsaturated fatty acids during frying.