A new continuous system of enzymatic hydrolysis coupled with membrane separation for isolation of peptides with angiotensin I converting enzyme inhibitory capacity from defatted corn germ protein
In this study, separation of peptides with Angiotensin I converting enzyme (ACE)-inhibitory capacity obtained from ultrasonically pretreated defatted corn germ protein (DCGP) by using a new continuous system of enzymatic hydrolysis coupled with membrane separation (EHC-MS) were investigated. Ultrasonic pretreatment was applied to enhance the enzymatic hydrolysis rate of DCGP, as proven in our previous study1, 2. The EHC-MS system was operated in two modes which included the batch system and continuous system with a feed from water and substrate continuously and was compared with the EH-offline-MS system. The selection of membrane was based on the hydrolysate fraction which had the highest activity for inhibition of ACE. The results showed that the 1–3 kDa fraction of DCGP hydrolysate had the lowest IC50 value (0.124 mg/mL) for inhibition of ACE. The degree of conversion (%) of DCGP and output of peptides per unit of the enzyme were significantly (P<0.05) increased by 55.3% and 55% in the EHC-MS batch process, and 79 % and 473% in the EHC-MS continuous operation compared to EH-offline-MS system. The EHC-MS using water and substrate-continuous feeding operation was noted to be the best in terms of a high degree of DCG protein conversion (75.68±1.34) and the output of peptides per unit of the enzyme (78.65±1.13). The results revealed that EHC-MS with constant water and substrate feeding method could present a better application in peptides production in the food industry.