Inhibition of frozen storage‐induced oxidation and structural changes in myofibril of common carp ( C yprinus carpio) surimi by cryoprotectant and hydrolysed whey protein addition

Summary The objective of the present study was to evaluate the efficacy of combined cryoprotectants (sucrose + sorbitol) and whey protein isolate (WPI) hydrolysates to inhibit protein oxidation and quality loss in common carp (Cyprinus carpio) surimi during frozen storage at −25 °C. With increasing storage time, the carbonyl content of myofibrillar proteins increased from 4.02 nmolmg‐1 protein (0 day) to 7.25, 6.31, 5.26 and 4.83 nmol mg−1 protein (180 days; P < 0.05) for the control and samples with cryoprotectants, with cryoprotectants + WPI hydrolysates and with cryoprotectants + propyl gallate, respectively; protein surface hydrophobicity and turbidity increased in a similar trend, while sulfhydryl content, Ca‐ATPase activity, protein solubility and protein thermal stability decreased (P < 0.05). These results suggest that treatments with combined cryoprotectants and antioxidative WPI hydrolysates offer an effective approach to reducing the extent of protein oxidation in common carp surimi, thereby limiting protein structural changes known to impair texture of surimi products.