Study On The Muscle Protein Composition Of Litopenaeus Vannamei And Its Meat Surimi Properties

In our country the Litopenaeus vannamei has high production which is rich innutrition.The main products of prawns were fresh and frozen shrimp, the products of theprawns had few varieties the deep process products are few, remain to be further improved.With the improvement of living standards and life rhythm speeding up, people paid moreand more attention to the nutrition and convenience of food. Shrimp surimi, regarded asChinese traditional food, are popular in the masses because of their delicious and goodtaste. Currently on the market, there are some products,such as meatballs, shrimp sausage,shrimp cake, bread shrimp meat stick and so on. Although there were many varieties, butquality of the products are difficult to keep good and many shrimp products are fish surimias the main raw material, then added the shrimp flavor to generate the taste of shrimp. Butthe characteristics of shrimp surimi products that using prawn as raw materials was hardlyever studied by others.In order to solve this problem, the optimum gelling conditions and additives werestudied to get the best properties of shrimp gel. In addition, the protein composition andnutrition was studied. It explored the effect of different treatments and different additiveson the properties of frozen shrimp. Then it illustrated the change from frozen storage toheat treatment and provide the theoretical basis for preventing the proteindenaturation.The main content and results were as follows.1. The chemical composition and nutritions value of the shrimp were studied. The resultsshowed that, the content of coarse protein and fat was19.72%and0.82%. Myofibrillarprotein had the maximum amount of nitrogen, followed by water-soluble protein,myofibrillar protein and non-protein nitrogen, with the content of64.30%. The amountof total amino in shrimp was followed by water-soluble protein, myofibrillar protein andstroma.Though they had different proportion of amino acid,the first restrictive aminoacid in them were similar. The molecular weight of matrix proteins, water-solubleprotein, salt soluble protein were respectively200kDa-19kDa,80kDa-27kDa,200kDa-45kDa.2. The paper aimed at searching the optimal processing conditions of Shrimp surimi usinggelling strength and the water loss as index. The results indicate that prepare gels, thesols were incubated in a temperature controlled water bath at40℃for1h followed byheating at90℃for30min. The gel strength was3.815×103g．mm and the water loss9.5%Salt. The optimum additives levels were salt3%, cassava starch8%, MTGase0.8u/g, isolated soybean protein3%, calcium lactate0.1%, phosphate compounds0.2%. Inthis way, the gel strength and and the water loss was3.815×103g．mm and9.5%.3. Different storing methods and ryoprotective agents were studied to give an insight intothe frozen characteristics by testing salt extractable protein content,Ca²⁺_-ATPaseactivity,total sulfydryl and disulfide bond content and gel properties. The results showedthat: all these methods could reduce the loss of salt-soluble protein and slow down thedecrease of Ca²⁺_-ATPase activity, sulphur content and gel strength.In addition,surfacehydrophobicity and water loss rate after gelling increased. The shrimp stored in liquidnitrogen had the best quality while shrimp with trehalose had the similar properties withthose stored at-70℃for12weeks.And the formation of microscopic structure wassmaller and more even.The denaturation tempreture of myofibrillar protein rised underDSC scanning.4. The effect of NaCl,and trehalose on the thermal characteristics of minced shrimp werestudied using freezing and melting characteristics in low-temperature phase transitionzone. The paper also explored the relationship of NaCl, trehalose with the thermalstability of minced shrimp in high-temperature phase transition zone. The results showedthat,NaCl and trehalose could make freezing temperature of shrimp muscle variedtoward lower than control. NaCl could make the freezing point lower and decrease theenthalpy of phase change. Trehalose maked the freezing point lower prior to rise whilethe the enthalpy of phase change decreased all the way.