Effects of freezing temperature and frozen storage on the biochemical and physical properties of Procambarus clarkii

The objective of this work was to investigate the freezing temperature (liquid nitrogen, −80, −30 and −18 °C) and storage duration (1, 4, 12 and 24 weeks) on the properties of red swamp crayfish. With the increase of frozen storage duration, the Ca2+-ATPase activity, salt soluble protein content, total and reactive sulfhydryl content of myofibrillar protein extracted from red swamp crayfish significantly decreased (P < 0.05) and expressible moisture significantly increased (P < 0.05), while the hardness increased at week 4 and decreased later (P < 0.05) except for samples subjected to freezing treatments at liquid nitrogen and −18 °C. The results suggested that the shelf-life of crayfish was recommended to be 1 month. Combination of the influence of temperature difference between freezing and storage and freezing rate on the final quality of product, freezing at −30 °C could be considered as the suitable processing for red swamp crayfish.