Effect of chitin hydrolysate on the denaturation of lizard fish myofibrillar protein and the state of water during frozen storage

We investigated the effect of chitin hydrolysate made from crustacean shells and cephalopod cartilage on the denaturation and state of water in lizard fish myofibrillar protein (Mf) during frozen storage at −25 °C for 120 days. The chitin hydrolysate (2.5–12.5 g dry weight) was added to 100 g of the Mf, and the changes in the Mf Ca–ATPase activity and the amount of unfrozen water in the Mf were examined during frozen storage. The addition of chitin hydrolysate markedly decreased the inactivation rate of the Mf Ca–ATPase. The amount of unfrozen water in the Mf increased upon the addition of chitin hydrolysate, and then decreased gradually during frozen storage. On the other hand, the amount of unfrozen water in the control dropped drastically during the initial period of frozen storage. At a concentration of over 5.0%, chitin hydrolysates completely suppressed the inactivation of the Ca–ATPase and maximized unfrozen water in Mf. These results suggest that chitin hydrolysates suppress the denaturation of Mf through enhancement of the interaction between the hydration sphere of the Mf and equatorial OH groups of chitin hydrolysate.