Continuous production of tempe-based bioactive peptides using an automated enzymatic membrane reactor

The utilization of bioactive peptides from food-grade raw materials has received increasing interest, especially for the production of functional foods. Within this study, a combination of fermentation and in vitro papain hydrolysis was devised to produce bioactive peptides exhibiting antioxidant property and angiotensin I-converting enzyme (AICE) inhibitory activity. The utilization of an automated membrane reactor system developed in this study could facilitate the continuous hydrolysis of tempe flour-rich in protein under constant flux, thus constant residence time operation. The optimum operating conditions were: [E]/[S] = 10% (w/v) and τ = 9 h. With a 10-kDa membrane filtration, the resulted antioxidant capacity and AICE inhibition were 0.033 mg AEAC/mL and 50.9%, respectively. Further separation of permeate with a 2-kDa membrane cut-off leveled off the antioxidant capacity but increased the AICE inhibitory activity (i.e., Reduction of IC50 of ~40%). By this, the obtained IC50 for AICE was 0.08 mg protein/mL, and this value was comparable with the IC50 values reported in the literature. The production of bioactive peptides from soybean through a combination of fermentation and in vitro enzymatic hydrolysis is limitedly reported. In this work, fermented soybean (tempe) was further hydrolyzed continuously using an automated membrane reactor. The hydrolysis under optimum operating conditions could increase the antioxidant activity and AICE inhibition of permeate. This work is expected to increase the commercialization of tempe-based food products by using safer technological approaches (i.e., fermentation and membrane technology). •An automated membrane reactor with constant flux operation was developed.•Antioxidant activity and AICE inhibition increased by 22% and 39%, respectively.•Enzyme-to-substrate ratio of 10% and residence time of 9 h were optimum conditions.•The lowest IC50 for AICE resulted from 2-kDa membrane filtration was 0.08 mg/mL.