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This study was aimed to produce bioactive peptides from optimally fermented tempe, and map their overall bioactivities. There were three preparative methods utilized for producing tempe-based peptides, such as water-facilitated extraction, alcalase, and papain hydrolysis, and in combination with membrane filtration. Fermenting soybean at 144 h was selected as the optimum time based on protein content and degree of hydrolysis. Through SDS-PAGE analysis, an increased degree of hydrolysis with longer fermentation time was confirmed. The best preparative method for producing bioactive peptides was through papain hydrolysis and followed by 5 kDa membrane filtration. By this, the enhancement was distinct for antioxidant activity, ACE-, α-glucosidase-, and Kunitz trypsin-inhibitory activity. The annotated peptide sequences resulting from Nano LC Ultimate 3000 Series System tandem Q Exactive™ Hybrid Quadrupole-Orbitrap™ Mass Spectrometer were matched with the BIOPEP database. The major bioactivities of tempe peptides obtained were as an ACE inhibitor, antioxidant, and antithrombotic., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Velvet beans are potential sources of parent proteins for bioactive peptide production. In this study, a combination of fermentation and neutrase-catalyzed continuous hydrolysis in an enzymatic membrane reactor was performed to produce antioxidative and angiotensin I-converting enzyme inhibitory (ACEi) peptides. The optimum operating conditions were t = 6 h and [E]/[S] = 7.5%. The resulting permeate, which was a<10-kDa fraction, exhibited antioxidant activity at 0.38 mg ascorbic acid equivalent antioxidant capacity (AEAC)/mL (2,2-diphenyl-1-picrylhydrazyl, DPPH inhibition) and 0.26 mg AEAC/mL (ferric reducing antioxidant power, FRAP), and ACEi activity of 81.02%. Further fractionation of the permeate increased the ACEi activity in which 2-kDa fraction showed the most potent activity (IC50 = 0.23 µg protein/mL). The IC50 value of the outcome was comparable to those reported in the literature for velvet bean-based peptides. Furthermore, this study suggests that neutrase is a good catalyst candidate for the synthesis of bioactive peptides from velvet beans. [ABSTRACT FROM AUTHOR]

Bioactive peptides showing Angiotensin-I-Converting Enzyme inhibitory (ACEi) activity can control blood pressure. They can be produced from various protein sources, including fish gelatin. This article provides a systematic review and metaanalysis on gelatin extraction, conditions of enzymatic hydrolysis, characteristics of ACEi peptides, and effect of hydrolysis procedure on ACEi peptides. Fish gelatin preparation uses various solutions such as acids, bases and distilled water. Enzymatic hydrolysis is carried out with an E/S ratio of 0.2 7% and temperature of 28.9 oC (using bromelain) and 60.6 oC (using Alcalase). Level of pH in hydrolysis also varied greatly, from 2 (using Pepsin) to 10 (using Purafect enzyme). The molecular weight of fish gelatin ACEi peptides ranged from 186-829 Da and the sequence of peptides was dominated by hydrophobic and aliphatic amino acids. Based on a meta-analysis, hydrolysis using enzyme combination resulted in more satisfying product than a single enzyme, represented with a combined effect size value of 0.593. [ABSTRACT FROM AUTHOR]

The Angiotensin-I-converting enzyme (ACE) is a peptidase with a significant role in the regulation of blood pressure. Within this work, a systematic review on the enzymatic preparation of Angiotensin-I-Converting Enzyme inhibitory (ACEi) peptides is presented. The systematic review is conducted by following PRISMA guidelines. Soybeans and velvet beans are known to have high protein contents that make them suitable as sources of parent proteins for the production of ACEi peptides. Endopeptidase is commonly used in the preparation of soybean-based ACEi peptides, whereas for velvet bean, a combination of both endo- and exopeptidase is frequently used. Soybean glycinin is the preferred substrate for the preparation of ACEi peptides. It contains proline as one of its major amino acids, which exhibits a potent significance in inhibiting ACE. The best enzymatic treatments for producing ACEi peptides from soybean are as follows: proteolytic activity by Protease P (Amano-P from Aspergillus sp.), a temperature of 37 °C, a reaction time of 18 h, pH 8.2, and an E/S ratio of 2%. On the other hand, the best enzymatic conditions for producing peptide hydrolysates with high ACEi activity are through sequential hydrolytic activity by the combination of pepsin-pancreatic, an E/S ratio for each enzyme is 10%, the temperature and reaction time for each proteolysis are 37 °C and 0.74 h, respectively, pH for pepsin is 2.0, whereas for pancreatin it is 7.0. As an underutilized pulse, the studies on the enzymatic hydrolysis of velvet bean proteins in producing ACEi peptides are limited. Conclusively, the activity of soybean-based ACEi peptides is found to depend on their molecular sizes, the amino acid residues, and positions. Hydrophobic amino acids with nonpolar side chains, positively charged, branched, and cyclic or aromatic residues are generally preferred for ACEi peptides. [ABSTRACT FROM AUTHOR]

• The optimum conditions were at [E]/[S] = 5%, pH = 7.5, and τ = 12 h. • The long-term continuous production was performed for 72 h. • Membrane fouling mitigations: threshold flux and membrane cleaning. • IC 50 values of 17.85 and 4.58 µg protein/mL for antioxidant and ACE inhibition. • DPP-4 and ACE inhibitor as the "theoretical" predominant activities. One of the main challenges hindering the commercialization of bioactive peptides is the lack of scalable and consistent production methods. To overcome this obstacle, an automated enzyme membrane reactor was used to continuously produce bioactive peptides from velvet bean (Mucuna pruriens). The optimum operating conditions were [E]/[S] = 5%, pH = 7.5, and τ = 12 h. The long-term continuous operation of the EMR system demonstrated its ability to maintain steady-state conditions. To minimize membrane fouling, an industrially viable strategy was employed, which combines operation at threshold flux and performing regular membrane cleaning. Further fractionation of the hydrolysates with a 2-kDa PES membrane resulted in the highest bioactivity. The IC 50 values for antioxidant and ACE inhibition were 17.85 and 4.58 µg protein/mL, respectively. To map the overall bioactivities of the hydrolysates, LC-MS analysis coupled with BIOPEP-UWM database was performed and obtained DPP-4 and ACE inhibitors as the predominant bioactive activities. [ABSTRACT FROM AUTHOR]

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 IC 50 of ~40%). By this, the obtained IC 50 for AICE was 0.08 mg protein/mL, and this value was comparable with the IC 50 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 IC 50 for AICE resulted from 2-kDa membrane filtration was 0.08 mg/mL. [ABSTRACT FROM AUTHOR]

This study investigates the continuous production of bioactive peptides from fermented velvet bean (Mucuna pruriens) using a cost-effective enzymatic membrane reactor. The optimal operating conditions for continuous hydrolysis were residence time of 9 h, enzyme-to-substrate ratio of 10%, and the use of a 5-kDa PES membrane for separation. The resulting permeate exhibited notable antioxidant activity with DPPH and FRAP assay values of 0.28 and 0.12 mg AEAC/mL, respectively, and an angiotensin-converting enzyme (ACE) inhibition of 83.28%. Further fractionation of the permeate with a 2-kDa membrane led to increased antioxidant activity and ACE inhibition, with resulting half maximal inhibitory concentration (IC 50) values of 7.6 and 0.6 μg protein/mL, respectively. Liquid chromatography-mass spectrometry was used to identify peptide sequences from the <2-kDa fraction, which were matched with the BIOPEP-UWM™ database. The results revealed that the fermented velvet bean peptides were predominantly dipeptidyl peptidase (DPP)-4 inhibitors and ACE inhibitors. The combination of a stirred tank reactor and membrane separation has the potential to enable the continuous production of bioactive peptides from velvet bean through the use of a freely suspended enzyme system. This reactor design offers an alternative solution to the existing delay in commercializing bioactive peptides, by (i) simplifying the industrial process development for continuous bioactive peptide production, (ii) eliminating the need for enzyme immobilization, and (iii) eliminating batch-to-batch variability in product quality and unproductive time associated with batch-wise production. • A cost-reduced EMR was successfully developed to facilitate continuous hydrolysis. • Residence time of 9 h and enzyme-to-substrate ratio of 10% were optimum conditions. • Low MW peptides permeated through 2-kDa showed higher bioactivities. [ABSTRACT FROM AUTHOR]