Unraveling the lipid photooxidation reactions in salmon oil under different light wavelength conditions via omics approaches.

Light wavelengths can lead to differences in flavor and components of food by lipid photooxidation. However, the relevant molecular mechanisms are still unclear. This study explored the effects of light wavelengths (365 and 405 nm) on volatile and nonvolatile compound structures in salmon oil, along with the underlying mechanisms, via lipidomics and oxlipidomics approaches. The shorter light wavelength more effectively catalyzed lipid oxidation, leading to greater diversity and higher content of volatiles. It more readily catalyzed the formation of carbonyl-containing compounds, such as aldehydes and enones, contributing to hot oil and fried fish flavors. The wavelength of 405 nm favored the formation of hydroxyl-containing compounds (enols and alcohols), leading to stronger seaweed and grass aromas. During photooxidation, 1O2 activated by light radiation preferentially reacted with double bonds at the ends of fatty acid chains with low steric hindrance, yielding more lipids with 16-20C fatty acids and small molecule volatiles (4C6C).