Cryoprotection of frozen-stored actomyosin of farmed rainbow trout (Oncorhynchus mykiss) by some sugars and polyols

A study on the effectiveness of several cryoprotectants (polydextrose, lactitol, glucose syrup and a mixture of sucrose and sorbitol [1:1]) in preventing freeze-induced perturbations of fish proteins was carried out in in vitro systems of natural actomyosin of rainbow trout (Oncorhyncus mykiss) muscle. Adding these cryoprotectants prevented drastic decreases of ATPase activity, as well as a rapid exposure of hydrophobic and sulphydryl groups on the protein surface. Cryoprotectants therefore slowed down the kinetics of aggregation via intermolecular secondary forces and disulphide bonds, thus greatly reducing losses in solubility.