Large yellow croaker (Pseudosciaena crocea) is the main coastal economic fish in China. After harvesting, the fish is rarely traded as the fresh product, but usually held in cold storage. Therefore, it is important to understand the quality changes occurring during preservation. In this study, freshly collected fishes were frozen by cryogenic (cabinet liquid nitrogen freezer at-40,-60 and-80 °C) and forced convection (ultra-low temperature freezer at-40 °C) freezing and stored at-18 °C for 6 months. Drip loss, relative moisture loss (RML), water holding capacity (WHC), color and texture of frozen fish were evaluated. The results showed that forced convection freezing had significantly higher drip loss and RML values compared to cryogenic freezing. WHC decreased dramatically irrespective of freezing methods employed. Cryogenic freezing at-60 and-80 °C had the highest yellowness values during storage; but the highest springiness, gumminess and shear force values were obtained only at-60 °C. We conclude that cryogenic freezing at-60 °C is appropriate for long-term storage of large yellow croaker.

The quality of perishable nutritious aquatic products can be sustained by the technique of cryogenic freezing. In this paper, physicochemical changes that aquatic products experienced in the cryogenic freezing process were reviewed. Due to the rapid freezing rates, cryogenic freezing resulted in the lower drip loss, higher water holding capacity and smaller ice crystals. The technique can obviate the protein denaturation of fish muscle, inhibit the formation of thiobarbituric acid reactive substances and reduce the lipid oxidation. The pH values, firstly decreased and then increased in the storage duration after cryogenic freezing. Texture of cryogenic aquatic products experienced the significant differences in different parameters. Few studies about color and sensory attributes of cryogenic aquatic products were investigated. Besides, quality drawbacks of cryogenic technique were still existed in defective morphology, thawing loss and other enzymatic changes of food products. Moreover, some methods applied recently to assist cryogenic freezing had been presented.