The influence of superchilling and cryoprotectants on protein oxidation and structural changes in the myofibrillar proteins of common carp (Cyprinus carpio) surimi

The objective of the present study was to investigate the effects of superchilling combined with cryoprotectants (a mixture of sucrose and sorbitol, 1:1) on protein oxidation and structural changes in common carp (Cyprinus carpio) surimi. With increasing storage time, the carbonyl content of myofibrillar proteins increased from 31.4 nmol/mg of protein (0 day) to 53.4, 46.3, and 39.7 nmol/mg protein at 35 days (P < 0.05) for −1 °C superchilled, −3 °C superchilled, and −3 °C superchilled with cryoprotectants samples, respectively. The incorporation of cryoprotectants into common carp surimi was found to significantly inhibit the formation of carbonyls (P < 0.05). The protein surface hydrophobicity increased in a similar direction, and the sulfhydryl content and Ca-ATPase stability decreased (P < 0.05). Emulsifying activities, gel textural hardness, springiness, and water binding capacity were also decreased, but they exhibited significant improvements at −3 °C when combined with cryoprotectants (P < 0.05). These results suggest that superchilling treatments at −3 °C combined with cryoprotectants offer an effective approach to reducing protein oxidation in carp surimi, thereby reducing protein structural changes known to impair the texture of surimi products.