Frozen storage actomyosin changes during

Jarenback and Liljemark (75,76) found similar changes in cod actomyosin solution and cod muscle during frozen storage. The denatured myosin was not extracted with salt solution. 

When 0.1 M sodium glutamate was added to carp actomyosin, denaturation during frozen storage was almost eliminated, as measured by changes in solubility, viscosity, ultracentrifugal behavior, ATPase activity and electron microscopic profiles (66,72) (Figure 3). This protective effect of sodium glutamate will be discussed below. 

Dyers outstanding work stimulated many studies of a similar nature leading to the firm conclusion that denaturation of actomyosin occurs at a significant rate during frozen storage of fish muscle and that the rate of denaturation can be used to estimate the rate of quality change of the fish. 

Actomyosin. Solubility. Studies have dealt with changes in the solubility of proteins during frozen storage of fish muscle or solutions of isolated actomyosin (33,51,52). Analysis by gel filtration of the salt extracts has shown that the actomyosin fraction decreases in solubility during frozen storage whereas the sarcoplasmic proteins remain essentially unchanged (53). 

The changes that occur in viscosity and ultracentrifugal pattern during frozen storage suggest deformation of actomyosin filaments into some denser, less asymmetric form. 

Electron Microscopy. Examination of fish proteins by electron microscopy conclusively shows that actomyosin aggregates during frozen storage (59,63,69). The change in structures of the extracted myofibrillar proteins and of the myofibril residues of frozen-stored cod muscle was studied by electron microscopy. The decrease in the number of actomyosin filaments and an increase in the number and size of large aggregate were found (69). Unfrozen carp actomyosin, either dissolved in 0.6M KC1 or suspended in 0.05M KC1, exists in a typical arrowhead... 

Changes in the shape of carp actomyosin filaments during frozen storage was also studied at various pH s (67). Pictures of actomyosin frozen and stored in 0.9M and 1.2M KC1 illustrated the dissociation of actomyosin into actin and myosin (1,2). 

Sultanbawa, Y. and Li-Chan, E.C.Y. 2001. Structural changes in natural actomyosin and surimi from ling cod (Ophiodon elongates) during frozen storage in the absence or presence of cryoprotectants. Journal of Agricultural and Food Chemistry 49 4716 725. 

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