CHANGES IN SALT EXTRACTABLE PROTEIN AND CA2+-ATPASE ACTIVITY OF MINCE FROM SILVER CARP (HYPOPHTHALMICHTHYS MOLLITRIX) DURING FROZEN STORAGE: A KINETIC STUDY

Changes in salt extractable protein (SEP) and Ca2 +-ATPase activity of actomyosin from washed and unwashed silver carp stored at -10 and -20C were investigated. The resultant decrease of SEP and Ca2 +-ATPase activity mainly occurred in the first 5 and 7 weeks, and the changes obeyed first-order model. The kinetic models of SEP and Ca2 +-ATPase changes were established during frozen storage. The rate constant k of decline in SEP and Ca2 +-ATPase activity of samples stored at -10C were higher than that of samples stored at -20C; the D value of samples stored at -10C were lower than that of samples stored at -20C. Compared with washed samples, unwashed samples had a higher rate constant k and activation energies E, and a lower D value. Activation energies E of SEP were higher than E of Ca2 +-ATPase activity in all samples. PRACTICAL APPLICATIONS Silver carp is one of the main freshwater fish species in China. Washing is an important step for fish processing and temperature is an important factor on fish protein storage. The changes of the kinetic models of SEP and Ca2+-ATPase during frozen storage can explain the effect of temperature and time on silver carp mince quality. These kinetic models can be used to predict the silver carp protein functional changes during frozen storage, and help to provide better methods to effectively utilize silver carp protein resource.