Research On Frozen Denaturation Of Cultured Pseudosciaena Crocea Protein And The Method Of Inhabition

Pseudosciaena crocea(Richardson) is a member of Richardson sections,yellow croaker species,which mainly grows in China,Japan and Korea.In China,it lives in South Sea,East Sea and the south of Yellow Sea,especially in Zhejiang and Jiangsu sea area.It is one of the chief economic marine fishes.Its meat is delicious with rich protein and poor cholesterol.Therefore,it is a kind of favourate food to people at home and abroad.In this paper,the frozen denaturation of cultured Pseudosciaena crocea at different temperatures was investigated,taking Ca²⁺-ATPase activity,salt dissolved protein content,pH value,SH content of myofibrillar protein,texture profile analysis(TPA) textural properties as indexes.Orthogonal experiment L₉(3³) was designed to study the effect of three kinds of antifreezes,polyphosphate,trehalose,sorbitol optimum on pH,salt dissolved protein content and Ca²⁺-ATPase activity of cultured Pseudosciaena crocea protein,so as to obtain the optimum method in preventing the frozen denaturation.The stability of antifreezes in preventing the frozen denaturation of cultured Pseudosciaena crocea protein was investigated with the extension of frozen storage period. Compared with fresh Pseudosciaena crocea,the changes of organization structure of cultured Pseudosciaena crocea at different storage temperature and the difference of organization structure between cultured Pseudosciaena crocea of frozen storage with and without antifreezes were investigated after three months by transmission-type electron microscope(TEM).The results are as follows:The frozen denaturation of cultured Pseudosciaena crocea protein at -18℃was worse than that stored at-50℃with the extension of frozen storage period.This result is similar to other results about frozen denaturation of marine fishes reported by scholars at home and abroad, that is,the lower frozen storage temperature is,the less extent of frozen denaturation of fish protein is.The optimum formulation of three kinds of antifreezes (polyphosphate,trehalose,sorbitol) in preventing the frozen denaturation was:polyphosphate 2%,trehalose 1%,sorbitol 2%.When antifreezes were added,pH,salt dissolved protein content,Ca²⁺-ATPase activity of cultured Pseudosciaena crocea were improved by 1.60%,33.98%and 43.52%respectively.At-18℃,the frozen denaturation of cultured Pseudosciaena crocea protein without antifreezes was worse than cultured Pseudosciaena crocea protein with antifreezes.It can be concluded that antifreezes can prevent the frozen denaturation of cultured Pseudosciaena crocea protein effectively.After three months of frozen storage of cultured Pseudosciaena crocea,the changes of organization structure of cultured Pseudosciaena crocea at different frozen temperature,the changes of organization structure of cultured Pseudosciaena crocea with and without antifreezes were observed and compared with the fresh cultured Pseudosciaena crocea.The results showed that the organization structure of cultured Pseudosciaena crocea stored at-50℃was better than that stored-18℃. The organization structure of cultured Pseudosciaena crocea with antifreezes was better than that without antifreezes.It can be concluded that lower frozen storage temperature and antifreezes can prevent frozen denaturation of cultured Pseudosciaena crocea protein effectively.