Proteomic analysis of exudates reveals the quality of marinated snakehead fish slice as affected by precooling and freezing treatments.

Proteomic analysis of exudates was carried out to reveal the mechanism underlying the quality of marinated snakehead fish slice as affected by precooling and freezing treatments. The slices treated with fast freezing techniques like liquid refrigerant immersion freezing (LRIF) and liquid nitrogen freezing (LNF) demonstrated superior slice quality and protein integrity, which is mainly due to smaller ice crystals, reduced oxidation, and better moisture retention. Precooling also contributed to preserving the quality. Proteomics exhibited that LNF group enhanced DEPs like heme‑oxygenase, heat shock proteins, myosin related proteins and uniquely enhanced sphingolipid metabolism indicating improved membrane protection and antioxidant system. Precooling further reduced oxidative changes across treatments with upregulation of E3 ubiquitin ligase and 26S proteasome as compared to slices without precooling. Overall, LNF combined with precooling most effectively maintained the fish slice quality and protein integrity, highlighting exudate proteomics as a valuable tool for optimizing freezing protocols.