Cod protein modifications induced by lipid oxidation-derived aldehydes: Insights into multi-aldehydes environment.

Cod and its products are particularly vulnerable to modifications caused by lipid oxidation products especially aldehydes. Most studies have focused on the effects of individual aldehydes. However, in real food systems, multiple aldehydes may interact competitively or synergistically to alter protein functionality. Here, a model system of a clickable probe, 4-(2-propyn-1-yloxy)-2-butenal (yne-ACR, 500 μM), with five reactive carbonyls (500 μM and 1000 μM): formaldehyde (FA), malondialdehyde (MDA), methylglyoxal (MGO), glyoxal (GO), and phenylacetaldehyde (PhA)-was used to simulate and visualize protein modifications. Results showed that FA and GO had no significant effect on yne-ACR-mediated modification, whereas MDA, MGO, and PhA significantly increased the modification levels and decreased intrinsic fluorescence, indicating conformational changes and increased binding availability. Physicochemical evaluations confirmed that aldehyde treatments markedly altered the microstructure, thermal stability, and volatile profile of cod protein. This work provides new insights into the mechanisms of multi-aldehydes co-modification of cod protein and offers a theoretical basis for controlling oxidation of foods.