| The Crayfish head has been made to basic material for condiment by hydrolyzing, and Crayfish shell has been used for the extraction of astaxanthin, which maximizes the utilization of waste.In the experiment, papain, pepsin, neutral proteinase, trypsin was used to hydrolyze Crayfish head, degree of hydrolysis (DH)and glutamate content as the main indicators and supplemented by sensory evaluate, selecting the best protease. Then single-factor test and central composite for the experimental method of combining the experimental design to study the temperature, time, E/S, pH, solid–liquid ratio of the five factors on the effects of enzymatic hydrolysis. The results showed that alkalic protease is the best enzyme, and its optimum conditions are rate of solid -liquid ratio 1:1.5, pH 9.1 and E/S 2024U/g under 61.6℃for 186min,under these conditions, the glutamate content is up to 110.9mg/100mL,and DH is 20.79% with rich shrimp flavor.The volatile components in Crayfish head and head hydrolysate were extracted by using two methods: SDE and SPME. And the components were isolated and identified by GC-MS. SPME method the compounds of extraction are essentially the lower boiling point, molecular smaller alcohols, aldehydes, ketones and other compounds, while SDE method could be more long-chain hydrocarbons, alcohols, aldehydes, acids, esters and other related compounds. Consequently, only the combination of SPME and SDE method, and can carry out comprehensive analysis of volatile substances.The free amino acid compositions ATP-related compounds and total creatinine content of Crayfish head and head hydrolysate were investigated. After hydrolysis, free amino acids increased obviously, reaching to 7.689g/100g, which essential amino acids (except tryptophan) content is up to 3.440g/100g, accounting for 44.79%; glutamate that tastes flavor is up to 1.081g/100g, which is much higher than the stimulation threshold (0.5g/100g), and a large increase(5.15 times); the amino acid which tastes strong sweet are high in content increase, such as: aspartic, henylalanine, threonine, praline, serine, glycine, lysine etc, other amino acids also increased to varying degrees. IMP, GMP, inosine and creatinine may act importantly and synergistically to the desirable taste of Crayfish head and head hydrolysate.Physical and chemical indicators of Crayfish head hydrolysate is analysed, heavy metals, mineral content and the health indicators as well. Metal content and health indicators of the product have met the requirements of GB for unique flavor and rich nutrition. The relative molecular mass distribution were studied. The results of relative molecular mass distribution determined by gel HPLC showed that the Mr distribution of enzyme-hydrolyzed peptide wasn't continuous, of which with Mr exceeding 1400 were 8.09%; medium-peptides with Mr 407~950 were 89.4%; and small-peptides and free amino acids with Mr less than 407 were 9.6%. By the research on the viscosity of Crayfish head hydrolysate, it finds that the concentration and viscosity increase exponentially When the concentration exceeds a certain limit, the concentration and viscosity increase exponentially, which is very important guiding significance in its further processingThe Crayfish shell has been hydrolyzed by papain for the extraction of astaxanthin. The optimal hydrolyzed condition was determined by the results of central composite for experimental design and the analyses of regression equation: 48.5℃of temperature, 5.8 of pH, 2522U/g of E/S, 63 min of hydrolyzed time. Under the experimentation condition used, the amount of total carotenoids is 115.761μg.g-1 wet, and the density of astaxanthin reaches to 13.06% by HPLC, whiche obviously enhances the density of astaxanthin.In this study, the enzyme complex flavor and the shrimp carotenoids was made, which maximized the utilization of waste, and provides the new way for comprehensive utilization of shrimp waste.
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