Effects of structural characteristics of phenolic compounds on oxidation of glycerol trioleate: Action rule and mechanism

Effects of structural characteristics of phenolic compounds on the oxidation of glycerol trioleate were investigated, and the action rule and mechanism were further explored. By using thermal and multispectral analyses, all tested phenolic compounds significantly inhibited the oxidation of glycerol trioleate, and reduced the decomposition of CC and ester bonds of glycerol trioleate, which were attributed to their capability to inhibit the production of free radicals. Quercetin and gallic acid were the most effective among the condensed and hydrolyzable phenolic compounds in present study, respectively. For condensed phenolic compounds, the hydroxyl groups in B ring, substitution in C ring, and the structure of C ring played a crucial role in their inhibitory action. For hydrolyzable phenolic compounds, the amount of hydroxyl groups and their molecular weight had obvious effects on their inhibitory action. According to the measurement of molecular electrostatic potential and frontier molecular orbitals by density functional theory, the large maximum electrostatic potential and the small energy gap value were beneficial to enhance the inhibitory capability of phenolic compounds on the oxidation of glycerol trioleate. All present results suggested the potential action rule and molecular mechanism about the inhibitory effects of phenolic compounds on the oxidation of glycerol trioleate.