Research On The Quality Change In Shrimp Out Of Water And Pro-treatment Process Before Frozen

Shrimp is one of aquatic products which contains different kinds of nutritious, It tastes delicious. However, Because shrimp has rich water and protein. It is spoilage easily and its shelf life is very short. After the shrimp dead, because of polyphenol oxidase, shrimp became black easily. Therefore, methods must be taken to preserve the shrimp timely. It is important to research on the quality change in shrimp out of the water and pro-treatment process before frozen.(1)In this paper, freshwater shrimp is raw material, Indicators are sensory evaluation,texture, pH, volatile basic nitrogen, thiobarbituric acid value, the total number of colonies,free amino acid content. It explores the quality changes of the shrimp in the state out of water.During the state out of water, the sensory evaluation, hardness, elasticity of the shrimp showed a downward trend;while the volatile basic nitrogen,thiobarbituric acid value, the total number of colonies showed a growth trend; the pH showed a downward trend after the first growth; shrimp total free amino acid was shown a downward trend.(2)Using freshwater shrimp under different processing conditions as raw material,indexes are sensory evaluation, pH, volatile basic nitrogen, water holding capacity, free amino acids, free fatty acids, volatile components.It explores the freshwater shrimp quality changes was explored during frozen. The study showed that the second group of sensory evaluation,water holding capacity of the decline is smaller than the first group;the second group of pH increase are bigger than the first group;while the volatile basic nitrogen content increase in the second group are less than the first group; polyunsaturated fatty acids are decreased,saturated fatty acid content showed upward trend; the total free amino acids in shrimp with different processes showed a downward trend.Solid phase micro-extraction method was used to measure shrimp volatile components.The result showed that twenty kinds of volatile components, including aldehydes, ketones, alcohols, hydrocarbons and other compounds.(3)The blanching time, the amount of salt, liquid ratio was factors. Astaxanthin content was the response value. The response surface analysis was conducted. When the time was1.79 min, solid-liquid ratio was 3.16g/ml, when the salt content was 1.66%. The maximum of astaxanthin 2.70726ug/g, The error comparing with the theoretical predictions was 2.16%.The result showed that the model can optimize reaction conditions drift hot shrimp and operability.