Abstract:

【Objective】 To establish an optimal enzymatic hydrolysis process for short peptides directly from rice bran under low and medium temperature. 【Method】 Quadratic regression orthogonal rotational combing design was used to determine the optimal enzymatic hydrolysis process. Anthrone colorimetry’s method was used to measure the carbohydrates content, pH-stat method to measure the degree of hydrolysis and Kjeldahl’s method to measure the recovery of protein. 【Result】 The optimum enzymatic hydrolysis conditions for short peptides were: reaction time of viscozyme for removing carbohydrate was 2 hours firstly, then protease hydrolysis with alcalase and trypsin was carried out at pH 8.2, temperature 45℃, the activity ratio between alcalase and trypsin was 59﹕41, the total enzyme activity was 5 750 U/g substrate, and 3 hours. Under such conditions the DH was 23.04%, the recovery of protein could reach up to 84.33%, TCA-SN was 68.40%, and the molecular weight of peptides was mainly concentrated at below 1 000 D. 【Conclusion】 It is a better approach with convenient operation and high recovery of protein for preparing rice bran short peptides compared to traditional ways of extracting protein first and then preparing short peptides with enzymatic hydrolysis.

Key words: rice bran, peptides, enzymatic hydrolysis process, degree of hydrolysis, recovery of protein