Effect of Incubation Conditions on the Protease Activity and Protein Property of Wheat Germ

Degreased wheat germ, after microwave treatment (600 W, 10 s), was incubated by different conditions for enhancing the activity of its endogenous proteases and increasing the level of polypeptides, including the incubation temperature and time, pH value of incubation solutions and ratio of the solution volume to the wheat germ weight. The results showed that enzymatic activities and polypeptides contents were both significantly affected by the temperature and time, pH value and ratio (P<0.05). A response surface optimization experiment was then conducted by using a Box-Behnken assay, revealing that the highest protease activity and polypeptide level, 3812.34 U/g and 303.12 mg/g, were obtained by a combination of the incubation temperature of 50 ℃ and duration of 6 h, pH of 4.5 and ration of 10:1 mL/g. These results revealed that optimization of culture conditions of wheat germ after degreasing and microwave treatments could effectively enhance the protease activity and polypeptide amount.