Effects of natural and synthetic antioxidants addition on the characteristic flavor and metabolites of walnut oil during oxidation

Antioxidants are commonly used to enhance the oxidative stability of oils, while its effects on flavor are rarely investigated. In this paper, the antioxidant capacity of two synthetic and two natural antioxidants in walnut oil (WO) were evaluated firstly. Tert -butyl hydroquinone (0.2 g/kg, TBHQ 0.2) and rosemary extract (0.5 g/kg, RE 0.5) exhibited better antioxidant activity. The volatile organic compounds (VOCs) profile changes of WO with TBHQ and RE addition were explored. It is suggested that TBHQ 0.2 and RE 0.5 can effectively delay the increase of VOCs, especially aldehydes. The concentrations of differential metabolites of WO during oxidation including 1-octen-3-ol, hexenal, and (E)-2-heptenal in RE 0.5 were lower than TBHQ 0.2 group, which were original from linolenic acid and linoleic acid. Sensory evaluation indicated TBHQ and RE can maintain the original aroma of WO during oxidation, while RE can enhance the green and fruity aroma.