Antioxidant effects of gallic acid alkyl esters of various chain lengths in oyster during frying process

Abstract

SummaryThe antioxidant effects of gallic acid (GA) and its alkyl esters including methyl gallate, ethyl gallate, propyl gallate, butyl gallate (GA‐C4), octyl gallate, lauryl gallate, hexadecyl gallate and octadecyl gallate in frying oil (soybean oil) and oyster during frying were investigated. Rancimat induction period (RIP) assay indicated GA and its alkyl esters effectively improved the oxidative stability of soybean oil according to the ‘polar paradox’; that is, the antioxidant effects of the polyphenols decreased in lipid system with the increasing of hydrophobicity. Results also indicated that GA and its alkyl esters all effectively retarded lipid oxidation in oyster tissue according to parameters including RIP, peroxide value and electron spin resonance assays. Moreover, the antioxidant efficiency in oyster increased with the alkyl chain length until GA‐C4, and thereafter, the antioxidant effects decreased, similar to the ‘cut‐off effect’. This study provides basic data for improving the oxidative stability of seafood during frying.