Biochemical changes in prawn protein during frozen storage

Abstract

Prawn is widely popular because of its nutrition and delicacy. The technology and scale of prawn aquaculture developed rapidly with high economic value. The prosperity of production and marketing grow continuously. Frozen storage,including frozen prawn,is widely used as a good method of preservation and processing. However,characteristics of prawn frozen storage and the impact on prawn quality had not been deeply studied yet. Three kinds of cultured prawn,dominanted in market,were chosen as study objects,and the salt solubility of myofibrillar,Ca 2+ -ATPase activity and sulfhydryl content were chosen for research indicators. The changes of the biochemical characteristics of prawn protein were investigated and the impact of different temperatures on quality of prawn was evaluated when stored at -10 ℃,-20 ℃,-30 ℃,-40 ℃ respectively. There are some differences among the three indicators of protein denaturation when applied to prawn. Ca 2+ -ATPase activity is the most sensitive. It can reflect different levels of protein frozen denaturation caused by different temperatures from -10 ℃ to -40 ℃. Different levels of protein frozen denaturation can also be reflected by the salt solubility of myofibrillar above -20 ℃ refrigeration. The salt solubility of myofibrillar decreased obviously at -10 ℃,but the trend declined below -20 ℃,and no significant difference was observed at -20,-30 and -40 ℃. The Ca 2+ -ATPase activity is more suitable for quality assessment of prawn. The Ca 2+ -ATPase activity of protein decreased more slowly as the temperature lowered,and the performance differences of Ca 2+ -ATPase can be distinguished easily during storage at -10 ℃ to -40 ℃. Sulfhydryl content changed a little when the storage temperature varied from -10 ℃ to -40 ℃. Prawn protein is more stable than most freshwater fish. The salt solubility,Ca 2+ -ATPase activity and sulfhydryl content of prawn protein all decreased more slowly than usual freshwater fish. The protein of prawn denaturated mildly during frozen storage. -20 ℃ is economical and reasonable as a frozen storage and it can be selected as the practical frozen temperature.