标题：Optimization of Ultrasound Pretreatments and Hydrolysis Conditions for Production of Angiotensin-I Converting Enzyme (ACE) Inhibitory Peptides from Sodium Caseinate Protein Using Response Surface Methodology
摘要：Objective: The aim of this study was to optimize the alcalse-catalyzed hydrolysis conditions of Single Frequency Counter Current Ultrasound (SFCU) pretreated sodium caseinate (NaCas). Methodology: Response Surface Method (RSM) was employed in order to maximize angiotensin-I converting enzyme (ACE)-inhibitory activity (Y1) and degree of hydrolysis (DH) (Y2). Sonication parameters were first optimized and then pretreatment of NaCas was performed. Substrate concentration (X1), enzyme to substrate (E/S) ratio (X2) and hydrolysis time (X3) were selected to optimize the response variables (Y1 and Y2). Statistical analysis indicated that linear, interaction and quadratic terms of X1, X2 and X3 had significant effects on the response variables. Results: The mathematical model has been developed and provided a statistically accurate prediction of Y1 and Y2. The optimal hydrolysis conditions for NaCas were substrate concentration of 9.90 g L1, E/S ratio of 14626 U g1 and hydrolysis time of 60 min. At the optimal conditions, the experimental values for ACE inhibitory activity (83.64%) and the DH (15.75%) were closed to the predicted values. Compared to control, ultrasound pretreatment increased DH and ACE-inhibitory activity by 3.35 and 31.80%, respectively and decreased IC50 by 27.94%. Conclusion: The optimized conditions would provide important information on proteolysis and bioactive peptides of NaCas to the food industry.
