Abstract: Acidity change and apparent viscidity change of yogurt mixed with different amount (5%,7.5% and 10%) and differenthydrolytic degree (3.12%,5.77% and 8.83%) pea-protein hydrolysate by Flavourzyme were studied in this paper. Rheologicalshear stress, parameter and viscosity index in different shear rate were studied in yogurt.The result showed that it took shortesttime to be the fermentive and for yogurt when milk was mixed with 7.5%～10% enzymatic soy-protein hydrolysate whichhydrolytic degree was 8.83%. The apparent viscidity of fermented yogurt was increased when milk was mixed with 10%DH 3.12% enzymatic soy-protein hydrolysate. Flexibility of yogurt was reduced when milk mixed with soybean hydrolysateand the yogurt was non-newtonian fluid. Shear stress of yogurt in high shear rate was far higher than CK when milk was mixedwith DH 3.12% enzymatic soy-protein hydrolysate.

Key words: yogurt, soy protein, enzymatic hydrolysis, rheological behavior