Production of Angiotensin-I-Converting Enzyme (ACE) Inhibitory Peptides during the Fermentation of Jack Bean (Canavalia ensiformis) Tempe

Background and Objective: Angiotensin-converting enzyme (ACE) inhibitory peptides from various food sources have been studied extensively. We are interested in studying the inhibition of ACE from fermented tempe made from the jack bean, which is a commonly used source of plant-based protein. The purpose of this study was to determine the optimal incubation period for the production of peptides with high ACE inhibitory activity. Materials and Methods: After soaking and boiling, the jack beans were inoculated with tempe inoculum and incubated for 0-120 h. During the incubation, various parameters, such as proteolytic activity, peptide content, hydrolysis degree, protein pattern and ACE inhibition, were monitored. All the parameters were measured using standard methods. Results: Tempe fermentation caused hydrolysis of the jack bean protein, producing soluble high molecular weight proteins (from previously insoluble) and protein fragments (monitored from SDS PAGE data). The highest protein hydrolysis occurred after 96 h fermentation period, which were observed from the highest proteolytic activity (25.39 units g–1), hydrolysis degree (19.85%) and peptide content (6.05 mg mL–1). The highest ACE inhibitory activity did not coincide with the highest levels of protein hydrolysis but rather were obtained after 72 h of tempe fermentation (IC50 = 1.03 mg mL–1). Conclusion: Jack bean tempe is a potential source of ACE inhibitory peptides, the highest ACE inhibitory activity occurred after 72 h of incubation.