Improvement Effect of Transglutaminase on Oil Absorption and Water Retention of Soybean Proteinase Isolates

Soy protein isolate(SPI)was digested with papain to obtain the enzymatic hydrolysates. Transglutaminase(TGase)was used to crosslink the enzymatic hydrolysates,and oil absorption and water retention were used as indicators to optimize the crosslinking conditions by the response surface optimization. The correlation between particle size,zeta potential,free amino content and oil absorption,water retention before and after modification was investigated. The results showed that,when the TGase addition amount was 21.2 U/g,pH value was 7.1,crosslinking temperature was 53.0 ℃ and crosslinking time was 1.2 h,the optimal oil absorption of enzymatic hydrolysates after TGase crosslinking was 5.41 g/g. Compared with the SPI hydrolysates before TGase modification(3.98 g/g),it was 35.93% higher. Compared with SPI(3.73 g/g),the increase was 45.04%. Under the conditions of enzyme addition amount of 20 U/g,pH value of 7.0,crosslinking temperature of 35 ℃ and crosslinking time of 1.0 h,the water retention of the enzymatic hydrolysates after TGase crosslinking was improved to 17.28 g/g. Compared with the SPI hydrolysates before TGase modification(14.82 g/g),it was 16.60% higher. And compared with SPI(14.42 g/g),the increase was 19.01%. There was a significant negative correlation between particle size and water retention. The absolute value of zeta potential had a significant positive correlation with oil absorption and a negative correlation with water retention.And the free amino content had a significant negative correlation with oil absorption. The correlation coefficients were -0.865,0.878,-0.531 and -0.595,respectively.