Changes in Quality and Myofibrillar Protein Functional Properties of Two Kinds of Cuttlefish during Frozen Storage

To investigate the changes of quality and myofibrillar protein functional properties of Sepiella maindroni and Sepia esculenta during frozen storage, the two kinds of cuttlefish were frozen at −18 ℃ for 0, 30, 60, 90 and 120 days. The water content, water activity, texture, color difference and total volatile base nitrogen (TVB-N) were measured. Hematoxylin-eosin (HE) staining and scanning electronic microscopy (SEM) were used to observe the changes of muscle quality of the two cuttlefish species. The functional properties of myofibrillar proteins of the two cuttlefish species were evaluated by total sulfhydryl, carbonyl content and Ca²⁺-ATPase activity. The results showed that compared with fresh cuttlefish, after 120 days of frozen storage, the water content and water activity of the two cuttlefish muscles to decrease, but the Sepia esculenta decreased faster. There was no significant difference in the elasticity of the two kinds of cuttlefish muscle, and the hardness, chewiness and adhesiveness decreased first and then stabilized. The whiteness, L^*, total sulfhydryl content and Ca²⁺-ATPase activity of the two cuttlefish species continued to decrease, TVB-N and carbonyl content to increase, and b^* showed a dynamic change trend of first decline and then rise. After 90 days of frozen storage, the TVB-N content of Sepiella maindroni and Sepia esculenta muscle was 19.00 and 20.22 mg/100 g, respectively. Compared with fresh cuttlefish, they increased by 29.41% and 73.42% respectively after 120 days of frozen storage, and the rise rate of Sepia esculenta was faster. After 120 days of frozen storage, the sulfhydryl content and Ca²⁺-ATPase activity of the two cuttlefish species decreased to the minimum, which decreased by 52.28%, 56.12% and 70.93%, 72.00%, respectively. Compared with fresh cuttlefish, the microstructure of frozen 120 d showed that the muscle tissue of Sepiella maindroni was gelatinized into minced meat, the muscle fiber distribution of Sepia esculenta was disordered and the pores were increased. The results provide theoretical support for the quality control of the cold chain storage process of Sepiella maindroni and Sepia esculenta.