Effect Of Ionic Strength On Enzymatic Gel Properties Of Soybean Protein Isolate

Soy protein isolate is a high quality protein resource extracted from soybean.it is rich in protein and is often used as a food additive in food production to play a functional role,such as acting together with Nacl to play a gel role in surimi products.Nowadays,the research on the structure and properties of soybean protein isolate is more common in China,but the research specializing in gelation is few.Therefore,in this experiment,soybean protein isolate was used as raw material,and three manufacturers soybean protein isolate(respectively,Jinlong,Yifahe,Shansong)were selected for experimental study.Through the physical and chemical test results of the isolated protein samples of Jinlong,Yifahe and Pinus tabulaeformis soybean,it is concluded that the water,protein,fat and ash contents of the samples of the three manufacturers have little difference.Among them,the protein content is about 90%,but not more than 90%;the water content of the three is 2-3%;the fat content of the three is 0.5-0.7%;the ash content of the three is 4-6%;therefore,the nutrient content of soybean protein isolate in the three manufacturers is basically similar.The amino acid components of the three samples were detected by the amino acid components of Jinlong,Yifahe and Pinus tabulaeformis soybean protein isolate.The amino acid ratio of the same type was almost close,the neutral amino acid ratio was about 52%,the acid amino acid ratio was about 30%,and the basic amino acid ratio was about 17%.There was no significant correlation between salt tolerance and amino acid composition of soybean protein isolate.The protein content of 7 S and 11 S was 90.08% and91.22%,respectively,according to the results of protein component detection.The gel strength of the isolated protein 0.0%,0.5%,1.0%,1.5%,2.0%,2.5%,3.0%,3.5%Na Cl,TG enzyme to the isolated protein results showed that the breaking force,sag depth and gel strength decreased with the increase of salt concentration under the hydration system.When the Na Cl concentration increased to 1.5%,the changes tended to be gentle;the slurry state was obviously thin;the elasticity decreased obviously,the taste became brittle and the microstructure became rough.The gel strength was determined by adding 0.0%,0.5%,1.0%,1.5%,2.0%,2.5%,3.0%,3.5%Na Cl,TG enzyme.The results showed that the breaking force,depth of depression and gel strength decreased with the increase of salt concentration in emulsifying system.After 5%,the changes of the three tend to be gentle;the slurry state is obviously thin;the elasticity is obviously reduced,the taste becomes brittle and the structure becomes rough.Through the orthogonal design of salt concentration(%),stirring out pulp temperature(℃),steaming temperature(℃)and steaming time(min)added in thousand-page tofu,it is concluded that the appearance and taste of thousand-page tofu made under the condition of salt concentration of 0.5%,pulp temperatureof 10℃,steaming temperature of 80℃ and steaming time of 25 min were the best,with the highest score and the best process parameter.This experiment verified the effect of ionic strength(i.e.,Na Cl concentration)on the gelation effect of soybean protein isolate.between 0~3.5% of the Na Cl concentration,the gel strength gradually decreased with the increase of salt concentration.As a result,the gel strength of the product should be affected by the addition of appropriate amount Na Cl,Na Cl in the production of the product,which provides a theoretical basis for the future production enterprises to improve the functional properties of the product.