Static magnetic field-assisted liquid nitrogen quick freezing and air-blast freezing for enhancing the quality of tilapia fillets: Improvement of physicochemical attributes and inhibition of protein oxidation

This study confirms that SMF-assisted quick freezing is a viable technology for enhancing the frozen storage stability and nutritional value of tilapia fillets. The effects of static magnetic field-assisted quick freezing (SMF) combined with liquid nitrogen and air blast freezing on the physicochemical quality and myofibrillar protein conformation of tilapia fillets during 12 weeks of frozen storage at −18 °C were evaluated. Under static magnetic field (85–105 mT) assistance, air blast freezing (BF) and liquid nitrogen freezing (LNF) cut total freezing time by 256.66 s and 366.67 s, and shortened the maximum ice crystal formation phase by 396.67 s and 39.07 s. SMF generated tiny uniform ice crystals to mitigate muscle microstructure injury and drip loss. Moderate SMF (60–80, 85–105 mT) preserved color, texture and water retention while restraining TVB-N and TBARS buildup. On day 84, BF 85–105 mT had 7.53% thaw loss; LNF 85–105 mT achieved the minimum 5.41% thaw loss and 75.46% water-holding capacity. Final TVB-N reached 13.68 mg/100 g (BF) and 11.26 mg/100 g (LNF) with slow accumulation. SMF also suppressed protein carbonylation and sulfhydryl oxidation, delayed tryptophan residue exposure and α-helix unfolding, and effectively stabilized protein structure. In summary, SMF-assisted freezing efficiently retarded the quality deterioration of frozen tilapia, which exhibits promising application potential for high-value aquatic product preservation.