Exploring the antioxidant “cut-off effect” of gallic acid alkyl esters in dried oysters (Crassostrea gigas) during storage

In some complex food matrices, lipophenols exert stronger antioxidant effects than free polyphenols due to their better amphiphilicity and solubility. The use of lipophenols of different chain lengths often presents a “cut-off effect” in real foods, but the reason is far from understood. This work compared the antioxidant capacity of ethyl gallate (EG), octyl gallate (OG) and myristyl gallate (MG) in dried oysters during storage. The oxidation rate of polyunsaturated fatty acids (PUFAs), oxidation inhibition rate of the antioxidants on PUFAs and the generation number of lipid hydroperoxides and aldehydes shown that the treatment of antioxidants effectively inhibited lipid oxidation during storage, and the inhibition ability in the OG group was significantly better than that in the other antioxidant groups, which was consistent with the as of the “cut-off effect”. The density functional theory (DFT) and the molecular dynamics (MD) simulation showed that this “cut-off effect” is related to the ability of the polyphenolic hydroxyl group at C4 to transfer hydrogen atoms and the effective concentration of lipophenols at the initiation site of lipid oxidation.