Suitability of chitosan as cryoprotectant on croaker fish (Johnius gangeticus) surimi during frozen storage

Effect of chitosan on physicochemical attributes of croaker fish surimi during storage at -20 +/- 2 A degrees C for 180 days was evaluated. The quality of croaker surimi added with 1% (w/w) chitosan was examined in terms of muscle protein, thaw drip, gel strength and Ca2+ ATPase activity comparing with those surimi samples added with 4% sucrose and 4% sorbitol. Surimi without any cryoprotectant was treated as control. Chitosan showed cryoprotective effect similar to commercial cryoprotectants as both of them minimized the negative effects of frozen storage on physico-chemical attributes of myofibrillar proteins. The residual Ca2+ ATPase activity and gel strength of surimi with chitosan were higher than those of control throughout the storage period. Ca2+ ATPase activity and gel strength had high positive correlation. It is concluded that chitosan was effective in preservation of croaker muscle protein native structure during 6 months of frozen storage and is comparable to other commercial cryoprotectants.