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.

Pola Perubahan Protein Koro Benguk (Mucuna pruriens) Selama Fermentasi Tempe Menggunakan Inokulum Raprima

Bioactive peptides (BPs) isolated from legumes have functional properties as healthy foods. These functional effects depend on their stability and bioavailability in the gastrointestinal tract before reaching the target organs. Therefore, it is necessary to disclose the factors that influence it and discuss the technical processing to develop its utilisation. This chapter discusses and summarises the bioactive activities of BPs from various legumes, factors and mechanisms related to the bio-assessability, stability, bio-availability and bioactivity of BPs. Furthermore, the development of BPs bioseparation was also discussed. The results show that the nature of BPs varies greatly depending on the legume source and the production method. Factors that influenced the bio-availability of BPs include molecular weight, charge, amino acid sequence, the presence of specific residues and hydrophobic amino acids, and resistance to the action of peptidase while in the digestive tract. However, some BPs showed increased bio-accessibility and bio-availability after being hydrolyzed by digestive enzymes. Processing technologies such as encapsulation allowing BPs to enter the body and undergo release and degradation by enzymes digestion. Further studies are required to understand the increase in the bioavailability of BPs, the safety of the food components produced, and their use in producing functional foods.

Purpose: The purpose of this paper is to understand the effect of hydrolysis by pepsin and pancreatin on the angiotensin-I-converting enzyme (ACE) inhibitory activity of bioactive peptide from pigeon pea tempe and the absorption of pigeon pea tempe peptide by using the everted gut sac method. Design/methodology/approach: The tempe was prepared by inoculating Raprima (Rhizopus oligosporus) on hulled-cooked pigeon pea for 48 h. The extraction was performed using the ultrasonic method at 40 kHz frequency and 100% ultrasonic power for 10 min. The extracted protein was placed in simulated gastrointestinal digestion using consecutive pepsin–pancreatin for 240 min. The hydrolysates were fractionated using a dialysis tube, and its absorption was assessed using the everted Sprague–Dawley rat gut sac. Findings: The tempe protein from the hydrolyzed pigeon pea exhibited higher ACE inhibitory (71.53%) activity than that from the boiled pigeon pea (53.04%) (p = 0.028). The bioactive peptide of the digested pigeon pea tempe consisted of low-molecular-weight peptides (<1 kDa). The fraction also showed the highest ACE inhibition activity among the others (IC50 = 0.61 mg/mL, p = 0.021). Bioactive peptides from pigeon pea tempe were absorbed well in the small intestine, mainly in the jejunum. The activity of the absorbed peptides did not change considerably. Originality/value: The activity of bioactive peptide of pigeon pea tempe was comparatively stable during digestion. It exhibited activity even after absorption in the small intestine. Thus, pigeon pea tempe can serve as an antihypertensive peptide source and alternative food for maintaining/reducing blood pressure.

The germination of lamtoro gung has been shown to increase the angiotensin-I-converting enzyme inhibitory (ACE-I) activity in previous studies. The 48 h germinated flour had the highest ACE-I activity. Administration of the gastrointestinal digestion (GID) simulation with commercial enzymes was expected to increase the ACE-I activity. However, the GID simulation to increase ACE-I in the germinated lamtoro gung flour has not been found. Therefore, this study aimed to evaluate the GID simulation of ACE-I peptides in sprouted lamtoro gung flour. This study also identified and characterised the peptide with the ACE-I activity. The GID simulation was performed using commercial pepsin (pH 2) and pancreatin (pH 7.5). Both simulations occurred at 37 °C for 240 min. The degree of hydrolysis, peptide concentration, and ACE-I activity was analysed. Samples with the highest ACE-I activity were then fractionated and identified, to determine the peptide responsible for the ACE-I activity. The 180 min GID simulation in the test sample showed the highest ACE-I activity (89.70%). This result was supported by an increased degree of hydrolysis (DH) and peptide concentrations throughout the GID simulation. The <1 kDa peptide fraction had the highest inhibitory activity and had the most elevated peptide portion (54.69%). Peptide sequences containing crucial amino acids were found in the <1 kDa peptide fraction. PRPPKPP, PPPPPGARAP, and PFPPSNPPP had proline in the C and N terminal residues. The peptides obtained also had other biological activities, such as a DPP IV inhibitor, an alpha-glucosidase inhibitor, and antioxidative activity. Based on the toxicity prediction, those peptides are non-toxic and safe to consume.