Effect of the phenolic extract of Camellia oleifera seed cake on the oxidation process of soybean oil by 1H nuclear magnetic resonance during frying.

The oxidation process of soybean oil enriching with the phenolic extract of Camellia oleifera seed cake (PE), tertiary butylhydroquinone (TBHQ) and tea polyphenol palmitate (TPP) was evaluated under frying condition with 1H nuclear magnetic resonance (NMR). The results showed that PE and TBHQ could inhibit the degradation of unsaturated acyl groups and reduce the generation rate and concentration of oxidative compounds, with PE having better performance. The hydroperoxides and their associated (Z , E)- and (E , E)-conjugated dienes of soybean oil were only detected at 220 min, and soybean oil with PE had the lower intensity of 1H NMR signals. In addition, the nine individual polyphenols significantly reduced during frying, and only three phenolic acids were detected even after 420 min, although their content was extremely low. All results suggested that phenolic extracts could provide an effective alternative to synthetic antioxidants during the frying process. • Effect of polyphenol on frying performance of soybean oil was studied by 1H NMR. • Degradation of acyl groups was significantly delayed after adding polyphenol. • Polyphenol markedly reduced the concentration of some oxidative compounds. • The content of individual polyphenol significantly reduced during frying. • The antioxidant mechanisms of polyphenols were proposed under frying condition. [ABSTRACT FROM AUTHOR]