Quality tracking of largemouth bass (Micropterus salmoides) fillets during superchilling storage by pretreatment with NaCl

The objective of this research was to investigate the effect of salt pretreatment (1 % and 2 %) on the physicochemical properties, sensory characteristics and safety indices of largemouth fillets during superchilling storage. During superchilling storage, the 2 % group had the lowest values of ice crystal formation temperature, thiobarbituric acid (TBA), total volatile basic nitrogen (TVB-N), and total viable counts (TVC), and the deterioration of fish quality in the 2 % group was significantly slower than that in the 1 % group (P<0.05). At the later stage of storage, low-field nuclear magnetic resonance (LF NMR) results showed that moisture in the fish fillets showed a mixture of ice crystals and water, and TBA, TVB-N, and TVC values were significantly higher in the salt-treated group (P<0.05); the proteins interacted with unfrozen fractions to form relatively ordered structures, which promoted the intensity of protein bands. The pH of the fillets transferred from neutral to weakly acidic throughout the period of storage, and the L*, W and b* values of the 2 % group were significantly lower (P<0.05) than those of the other two groups. The results of shear force, microstructure and western blot (WB) indicated that salt pretreatment significantly improved fillet tenderness and odor. These indicated that the ideal salt pretreatment concentration and quality of the bass fillets for superchilled storage were 2 % and 21 d, respectively. This study provides a theoretical basis for the application of the preservation of aquatic products.