Cryoprotective effect of low molecular weight collagen peptides on myofibrillar protein stability and gel properties of frozen silver carp surimi

This study was aimed to investigate the cryoprotective effects of collagen peptides (10 g/kg; Collagen A, about 4500 Da; Verisol, 2000-3000 Da) on myofibrillar protein (MP) from silver carp surimi and the effects of collagen peptides on the characteristics of surimi gels during frozen storage (- 18 degrees C, 3-30 days) in comparison with that of a commercial cryoprotectant (40 g/kg sorbitol and 40 g/kg sucrose), sericin peptides (10 g/kg, about 3500 Da) and the control group (without cryoprotectant). The results indicated that Verisol, a collagen peptide with low molecular weight, was the optimal cryoprotective agent for the frozen storage of silver carp surimi. After 30 days of frozen storage, the MP from frozen surimi with Verisol contained 6.0-33.5% less carbonyls (26.8 +/- 0.3 mu mol/g), and 0.6-99.6% more free sulfhydryl (84.0 +/- 0.4 mu mol/g), as well as exhibited 17.6-47.1% greater Ca2+-ATPase activity (0.23 +/- 0.02 mu mol Pi/mgprot/hour) and 5.8-58.2% more extractable salt-soluble proteins (45.3 +/- 1.0%) in comparison with that of the other four treatments. In addition, the water holding capacity (94.2 +/- 2.2%), gel strength (314.8 +/- 8.0 g center dot mm) and whiteness (79.1 +/- 1.3) of the surimi gels with Verisol were also significantly better (p < 0.05) than that of the other treatments.