The Research Of Coating Treatment And Its Quality Of Grass Carp During Frozen Storage

The raising quantity and production of freshwater fish in China are ranking first in the world, the harvest time of freshwater fish is concentrated, more than70%of the harvest freshwater fish are stored in the form of frozen, however, freezing is easy to cause denaturation of fish protein, the taste、texture and protein quality of fish get worse when thawed, which seriously affected the market price of freshwater fish and hindered the development of freshwater fishery in China. Therefore, it is necessary to take some actions to solve the problem that the taste、texture and protein quality of frozen fish get worse. Because of the characteristics of pure nature、safe、stable and having special physiological functions、trehalose、chitosan and sodium alginate are called Functional sugar,at present, trehalose、chitosan and sodium alginate have been widely used in the food quality improvement. In this paper, we studied the effect of trehalose、chitosan and sodium alginate coating treatment on the sensory、texture and protein quality of grass carp during frozen storage using grass carp which occupy the first of raising quantity and production of freshwater fish of China as the test material, aimed at providing theoretical foundation for coating technology of aquatic products. The full text research contents and research results are as follows:1.The effect of trehalose、chitosan and sodium alginate coating treatment on the sensory quality and texture property of grass carp during frozen storage. Using trehalose、chitosan and sodium alginate coating process respectively, the sensory quality indexes and texture property indexes of grass carp can get enhancement and improvement to a certain extent during frozen storage. The sensory quality of non-coating process control group is not fresh in the storage period of the90d, however, the sensory quality of6%or9%tehalos、1.0%chitosan and2%sodium alginate coating treatment group are fresh in the all storage period. Seeing in comprehensive evaluation, the improvement of trehalose for the sensory quality and texture property is superior to chitosan and sodium alginate, and the improvement of chitosan for the sensory quality and texture property is superior to sodium alginate.2.The effect of trehalose、chitosan and sodium alginate composite coating treatment on the protein quality of grass carp during frozen storage. Through the single factor test,we know that the optimal concentration of trehalose is2.0%, the optimal concentration of chitosan is0.5%,the optimal concentration of alginate sodium is0.6%,through the orthogonal test design, we find out the optimal coating treatment group:A2B2C3, namely2.0%trehalose、0.5%chitosan and0.8%sodium alginate, storage experiment was carried out on the grass carp block under the condition of this coating process, the results showed that Using trehalose%chitosan and sodium alginate composite coating treatment, the falling of salt soluble protein、 Ca2+-ATPase activity and the total-SH of grass carp are significantly higher than uncoating treatment control group during frozen storage(p<0.05).Therefore, using the optimal solution which is choosing from orthogonal test design to deal with grass carp of frozen storage,the protein quality of grass carp has certain stability.3.The correlation analysis of sensory、texture and protein quality of grass carp during frozen storage.Through measuring each sensory quality index、each texture property index and each protein quality index, we studied the correlation among sensory、texture and protein quality of grass carp, the results showed that:the texture property indexes of hardness has very significant positive correlation with the sensory quality indexes of sensory score, the texture property indexes of springiness has very significant positive correlation with the sensory quality indexes of elasticity and sensory score, the texture property indexes of chewiness has very significant positive correlation with the sensory quality indexes of chew and sensory score, the salt soluble protein has very significant positive correlation with the sensory quality indexes of odor、taste and sensory score, Ca2+-ATPase activity has very significant positive correlation with the sensory quality indexes of odor、elasticity and sensory score and the texture property indexes of hardness and springiness; the salt soluble protein has very significant positive correlation with the texture property indexes of springiness and chewiness and has has very significant negative correlation with the texture property indexes of adhesiveness.