Abstract
To elucidate the effect of freezing rate on the denaturation of myofibrillar protein, we employed a temperature programmable freezer to control the freezing rate. Freezing rates were set from 0.01 to 1 °C/min. Denaturation of myofibrillar protein was assessed by measuring Ca-, Mg-, EDTA(K)- ATPase activities and salt solubility. Freezing at all rates slightly reduced the Ca-ATPase activity, but the difference in the inactivation caused by quick (1°C/min) and slow (0.01°C/min) freezing was less than 12 %. Freezing enhanced the Mg-ATPase, and reduced the EDTA(K)-ATPase activities. The changes were a little greater for the samples frozen slowly indicating that change in the interaction between myosin and actin was modified when frozen slowly. No decrease in the salt solubility was detected for the samples at any freezing rates. The samples were subsequently frozen stored at various temperatures. Myosin denaturation progressed slowly during the storage, and the rate was strongly dependent on the storage temperature. Therefore, it was concluded that freezing rate slightly affected the denaturation of myofibrillar proteins, and storage temperature more severely affected the denaturation.
