Changes in lipids in light salt dry-curing (LSD) grass carp muscle stored at 4 ℃ for 15 days were investigated to clarify the effect of LSD on lipid transformation. A total of 1265 lipid molecules from 35 subclasses were identified in the grass carp muscle. LSD promoted lipid conversion in early cold stage (0−6 days) but inhibited it later (6−15 days). Phosphatidylethanolamine (16:1e/22:6), phosphatidylcholine (16:0/20:4) and triacylglycerol (18:0/16:0/20:4) might be biomarkers of inhibited lipid corruption. The metabolisms of glycerophospholipid, fatty acids and arachidonic acid were crucial in restraining lipid transformations. Thiobarbituric acid reactive substances in LSD-pretreated muscle were significantly increased. LSD significantly increased acid lipase and phospholipase activities during early cold stage, but this effect decreased with refrigeration time. The lipid profile of LSD-pretreated grass carp muscle showed no significant change on day 15 of refrigeration. Consequently, LSD inhibited the lipid degradation of grass carp muscle during extended cold storage.

To investigate the inhibitory mechanism of ice-temperature combined with tea polyphenol (TP) treatment on flavor deterioration of Snakehead fish fillets during storage, lipidomics and microbial diversity analyses were performed. Lipidomic analysis via LC-MS/MS revealed that ice temperature and TP treatment significantly reduced the oxidation of polyunsaturated fatty acids (PUFAs), decreasing the generation of flavor compounds derived from lipid peroxidation, such as aldehydes (e.g., hexanal, nonanal), alcohols (e.g., 1-octen-3-ol), and esters. This effect was attributed to the ability of TP to scavenge lipid oxidation-derived free radicals, thereby suppressing the decomposition of PUFAs and the subsequent formation of key off-flavor compounds. Metagenomic sequencing showed that ice temperature combined with TP markedly inhibited the proliferation of dominant spoilage microbes (e.g., Pseudomonas, Acinetobacter, Shewanella, Aeromonas), reducing microbial-mediated lipid and protein degradation. The synergistic effect of ice temperature and TP not only delayed the increase in spoilage-related volatile substances but also maintained microbial community stability, as evidenced by lower OTU diversity and reduced abundance of odor-producing bacteria. Collectively, the ice temperature and TP treatment together extend the shelf life of Snakehead fish by concurrently suppressing lipid oxidation and microbial growth. This approach offers a new way to keep the flavor of aquatic products during storage.