Influence of triacylglycerol structure on the formation of lipid oxidation products in different vegetable oils during frying process.

The deterioration of frying oil significantly affects the quality of fried foods, leading to the formation of harmful oxidation products. This study examined how triacylglycerol (TAG) degradation influences both non-volatile and volatile oxidation products in frying oils. The sn-1/3 position of unsaturated fatty acyl chains was key to TAG degradation during frying. After 32 h, soybean oil showed higher levels of polymerized TAG products, 2,4-decadienal, (E)-2-heptenal, (E,E)-conjugated dienes, 4-oxo-alkanals, and epoxides compared to other oils. Rapeseed oil, however, had higher levels of glycerol core aldehydes, (E,E)-2,4-alkadienals, and n-alkanals. Correlation analysis suggested that thermal oxidation was more pronounced in the unsaturated TAGs of soybean and rapeseed oils, likely due to their abundant free radicals and low short-chain fatty acid content. The polar compound composition of TAG heating systems further supported the above conclusions. These results provide a better understanding of oxidative degradation in frying oils, focusing on TAG profiles.