Partial freezing as a means of preserving the feshmess of fish-II changes in the properties of protein during the storage of partially frozen sea bass muscle.

In order to develop methods for preserving the freshness of fish over a period of a few weeks, the effect of partial freezing on muscle protein was investigated. Sea bass muscle was alternatively stored at-3°C (partial freezing) or in ice for 2 weeks. The extractability of myofibrillar proteins remained at a high level in the partially frozen muscle, while in the iced muscle it tended to decrease during storage. The rate of formation of gel fraction protein was slower in the partially frozen muscle than in the iced muscle. Specific ATPase activity of the actomyosin from the partially frozen muscle and the iced muscle also decreased slightly during storage. The actomyosin from the partially frozen muscle stored for 2 weeks exhibited superprecipitation, while that from the iced muscle did not. The ATP-sensitivity of the actomyosin from the partially frozen muscle was higher than that from the iced muscle. These changes or trends indicate that some denaturation took place in the myofibrillar protein. The rate and extent of protein denaturation, however, were much smaller in the partially frozen muscle compared to those in the iced muscle.