Qualitative Changes of Squid (Loligo japonica) Under Different Frozen Storage Temperatures

Abstract:

Because squid (Loligo japonica) is not one of the traditional food sources in many countries, systematic studies on its nutrition and frozen storage, even in countries where there is a long history of squid consumption, have been lacking. In this study the squids were frozen at –20℃, –30℃, and –50℃ for 90 days to investigate the change in the meat quality and stability under different temperatures. The quality was evaluated every 15 days during the frozen storage according to the sensory evaluation and parameters such as the total volatile basic (TVB-N), the myofibrillar protein content, Ca2+-ATPase activity, the sulfhydryl content, and thiobarbituric acid reactive substances (TBARS). The results showed that Ca2+-ATPase activity and mouth feel decreased with the prolonged time of frozen storage at different temperatures. In the first 15 days, decline in the Ca2+-ATPase activity of both samples was the fastest, and it slowed down afterward. The contents of myofibrillar protein and sulfhydryl was first slightly increased and then decreased. The values of TVB-N and TBARS were elevated in frozen storage at all temperatures; the higher the storage temperature, the more rapidly these values rose. The values of TVB-N and TBARS were increased at a much higher rate after about 45 days, which indicated the deterioration in meat quality. Microstructural analysis of squid showed that the muscle fiber bundles became loose during the frozen storage. The storage temperature significantly affected the rate of decline in squid quality. Storage at –30℃ and –50℃ better preserved the quality compared to –20℃. Therefore, –30℃ or below could be the recommended storage temperature.