•Low-molecular-weight collagen peptides are associated with various health benefits.•Enzymatic hydrolysis remains the major way to prepare LMW collagen hydrolysates.•Cross-link and hydroxyproline in ...collagen contributes to its resistance to hydrolysis.
Collagen hydrolysates (peptides) derived from food processing byproducts have been used to produce commercially valuable food ingredients due to their potential to trigger certain desirable physiological responses in the body. Low-molecular-weight (LMW) collagen hydrolysates are generally thought to exert better bioactivities than their larger counterparts. However, the preparation of LMW collagen hydrolysates is often impeded by their special structure, cross-linking, and hydroxyproline. This review briefly introduces the motivation of the food industry to prepare LMW collagen hydrolysate from food processing byproducts. We further summarize recent progress on the preparation of LMW collagen hydrolysates and methods to determine the molecular weight. We then discuss the challenges and then provide perspectives on future directions in preparing LMW collagen hydrolysates.
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•Thermoase and pepsin-digested pea protein hydrolysate showed ACE2 up-regulating property in vascular smooth muscle cells.•A peptide with the sequence of AKSLSDRFSY was characterized ...from pea protein hydrolysate as an ACE2 up-regulator.•LSDRFS and SDRFSY identified from AKSLSDRFSY digests showed comparable activity as the parent peptide.
Angiotensin converting enzyme 2 (ACE2) degrades vasoconstricting angiotensin II (Ang II) into angiotensin (1–7), exerting protective effects in cardiovascular system; thus, ACE2 is considered as a novel target for cardiovascular therapy. The objectives of this study were to identify ACE2 up-regulating peptides from pea protein hydrolysate based on activity-guided purification. Pea protein hydrolysate prepared by a combination of thermoase and pepsin was subjected to various chromatographic fractionation; a peptide with the sequence of AKSLSDRFSY was identified as a novel ACE2 up-regulating peptide. AKSLSDRFSY was resistant to pepsin but not pancreatin in an in vitro digestion system. The resulting new sequences after digestion were characterized. Fragments with the sequences of LSDRFS and SDRFSY showed comparable effects in up-regulating ACE2 expression in vascular smooth muscle cells as the parent peptide. Future study will evaluate in vivo efficacy of the characterized pea protein-derived peptides.
•Postmortem quality changes of black carp muscle were evaluated.•Low salt and sugar dry-curing can keep a good quality of black carp fillet.•Low salt and sugar dry-curing reduced biogenic amine ...production of black carp fillet.•Sugar treatment reduced pH value and decreased TVB-N production of black carp fillet.•Low salt and sugar dry-curing is a safe and healthy preservation for freshwater fish.
The effects of low salt and sugar dry-curing on the quality changes of black carp (Mylopharyngodon piceus) fillets stored at 4°C were evaluated by sensory, physical, chemical, and microbiological methods. Fish samples were left untreated (control), or were dry-cured with 1.5% salt (T1) or 1.5% salt+1.2% sugar (T2). Curing treatments reduced chemical changes reflected in HxR, Hx, pH, and total volatile base nitrogen (TVB-N); decreased cooking loss; and increased overall sensory quality of fish (p<0.05) compared to untreated samples. Significantly lower values of cadaverine and putrescine were observed in T1 and T2 compared to the control after the 2nd and 4th day, respectively (p<0.05). There were significant differences (p<0.05) between T1 and T2 for pH, TVB-N, total aerobic counts (TAC), and sensory characteristics. Sensory characteristics were significantly correlated with TAC, TVB-N, putrescine, and cadaverine in all samples (p<0.01).
Proteases, especially microbial proteases, are widely used in food processing. The purpose of this study was aimed to purify an extracellular protease produced by the strain
QB7 and to evaluate its ...ability in hydrolyzing meat proteins and generating antioxidant and anti-inflammatory peptides. The optimal conditions for producing the enzyme were as follows: inoculum ratio, 10%; initial pH, 6.5; temperature, 32 °C; incubation time, 36 h; and rotation speed, 160 rpm. The protease had a molecular weight of approximately 47 kDa, possessing the optimal activity at 50 °C, pH 7.0, The protease was stable at pH 4.0-8.0 and 30-60 °C, and the activity was improved by Na
, Mg
, Ca
, and Zn
ions, whereas it was inhibited by Cu
, Co
, Fe
, Ba
, Fe
, β-M, and ethylene diamine tetraacetic acid disodium salt (EDTA). The protease could effectively hydrolyze meat proteins, and the generated hydrolysate could significantly inhibit tumor necrosis factor-alpha (TNFα)-induced oxidative stress, including superoxide and malondialdehyde levels and inflammation (vascular adhesion molecule-1 VCAM-1 and cyclooxygenase 2 COX2)) in human vascular EA.hy926 cells. The present findings support the ability of
QB7 protease in generating antioxidant and anti-inflammatory peptides during the fermentation of meat products.
Introduction
Cassava leaves are the agro-industrial by-product considered to be one of the most vegetable resource protein-richis.
Methods
This study aimed to optimize the enzymatic hydrolysis of CL ...proteins using Alcalase 2.4 L and studied the antioxidant properties of the hydrolysate. Effects of pH (7.0–10), temperature (40–65 °C), and enzyme/substrate (E/S) ratio (0.015–0.1 EU/ g protein) on the efficiency of protein extraction (E) (%), protein content (P) (%), and antioxidant activity (TEAC) (µmol TE/g) of the CL hydrolysate (CLH) were conducted. The models obtained were optimized through response surface methodology to maximize the value of P, E, and TEAC, respectively. Degree of hydrolysis, antioxidant activity (TEAC, ORAC, and FRAP), total phenol content (FT), and total protein content of CLH obtained under the optimal condition were measured. Amino acid composition of CLH with higher antioxidant activity was determined. CLH was fractionated by ultrafiltration into four fractions, whose antioxidant activities were then assessed in rat aortic vascular smooth muscle A7r5 cells. The fraction with the greatest activity was further fractionated based on hydrophobicity.
Results
The results showed that response variables depended on pH, E/S, and time used in the hydrolysis reaction. The fractionation process enriched antioxidant peptides, as reflected in the enhanced antioxidant activity of fractions in VSMCs. The antioxidant capacity of CLH or its derived fractions, as determined by chemical assays, corresponded with their cellular antioxidant capacity in VSMCs.
Conclusions
Our study shows the potential of cassava leaf as a source of producing antioxidant peptides.
Spent hens are a major byproduct of the egg industry but are rich in muscle proteins that can be enzymatically transformed into bioactive peptides. The present study aimed to develop a spent hen ...muscle protein hydrolysate (SPH) with antihypertensive activity. Spent hen muscle proteins were hydrolyzed by nine enzymes, either individually or in combination; 18 SPHs were assessed initially for their in vitro angiotensin-converting enzyme (ACE) inhibitory activity, and three SPHs, prepared by Protex 26L (SPH-26L), pepsin (SPH-P), and thermoase (SPH-T), showed promising activity and peptide yield. These three hydrolysates were further assessed for their angiotensin-converting enzyme 2 (ACE2) upregulating, antioxidant, and anti-inflammatory activities; only SPH-T upregulated ACE2 expression, while all three SPHs showed antioxidant and anti-inflammatory activities. During simulated gastrointestinal digestion, ACE2 upregulating, ACE inhibitory and antioxidant activities of SPH-T were not affected, but those of SPH-26L and SPH-P were reduced. ACE inhibitory activity of gastrointestinal-digested SPH-T was not affected after the permeability study in Caco-2 cells, while ACE2 upregulating, antioxidant and anti-inflammatory activities were improved; nine novel peptides with five–eight amino acid residues were identified from the Caco-2 permeate. Among these three hydrolysates, only SPH-T reduced blood pressure significantly when given orally at a daily dose of 1000 mg/kg body weight to spontaneously hypertensive rats. SPH-T can be developed into a promising functional food ingredient against hypertension, contributing to a more sustainable utilization for spent hens while generating extra revenue for the egg industry.
Spent hens are egg-laying hens reaching the end of their egg-laying cycles, being a major byproduct of the egg industry. Recent studies have been focusing on finding new value-added uses for spent ...hens. We have previously identified four bioactive peptides from spent hen muscle proteins, including three angiotensin-converting enzyme (ACE) inhibitory (ACEi) peptides (VRP, LKY, and VRY), and one ACE2 upregulating (ACE2u) peptide (VVHPKESF (V-F)). In the current study, we further assessed their antioxidant and cytoprotective activities in two vascular cell lines-vascular smooth muscle A7r5 cells (VSMCs) and endothelial EA.hy926 cells (ECs)-upon stimulation by tumor necrosis factor alpha (TNFα) and angiotensin (Ang) II, respectively. The results from our study revealed that all four peptides attenuated oxidative stress in both cells. None of the investigated peptides altered the expression of TNFα receptors in ECs; however, VRY and V-F downregulated Ang II type 1 receptor (AT
R), while V-F upregulated the Mas receptor (MasR) in VSMCs. Further, we found that the antioxidant effects of VRP, LKY, and VRY were likely through acting as direct radical scavengers, while that of V-F was at least partially ascribed to increased endogenous antioxidant enzymes (GPx4 and SOD2) in both cells. Besides, as an ACE2u peptide, V-F exerted antioxidant effect in a MasR-dependent manner, indicating a possible involvement of the upregulated ACE2-MasR axis underlying its antioxidant action. The antioxidant activities of VRP, LKY, VRY, and V-F in vascular cells indicated their multifunctional properties, in addition to their ACEi or ACE2u activity, which supports their potential use as functional food ingredients against hypertension.
•Five potent ACE inhibitory peptides were identified from spent hen muscle proteins.•Four novel ACE2 upregulating peptides were identified from spent hen muscle proteins.•Peptide VKW showed both ACE ...inhibitory and ACE2 upregulating activities.•Peptides derived from hen muscle can be used for antihypertensive applications.
The study explored the use of spent hen, a major egg industry byproduct, as the starting material for preparing antihypertensive peptides. While previous studies were focused mainly on ACE inhibitory (ACEi) peptides, this work also studied peptides with ACE2 upregulating (ACE2u) activity, an emerging target for treating hypertension. Spent hen muscle protein hydrolysate prepared by thermoase (SPH-T) exhibited both ACEi and ACE2u activities. After ultrafiltration and chromatographic fractionation, five potent ACEi peptides, VRP, LKY, VRY, KYKA, and LKYKA, with IC50 values of 0.034–5.77 μg/mL, respectively, and four ACE2u peptides, VKW, VHPKESF, VVHPKESF and VAQWRTKYETDAIQRTEELEEAKKK, which increased ACE2 expression by 0.52–0.84 folds, respectively, were identified; VKW also showed ACEi activity. All peptides, except for VRP, are susceptible to degradation during the simulated gastrointestinal digestion. Our study supports the potential use of spent hens as antihypertensive functional food ingredients and nutraceuticals.
This paper presents a distributed computing architecture for solving a distribution optimal power flow (DOPF) model based on a smart grid communication middleware (SGCM) system. The system is modeled ...as an unbalanced three-phase distribution system, which includes different kind of loads and various components of distribution systems. In this paper, fixed loads are modeled as constant impedance, current and power loads, and neural network models of controllable smart loads are integrated into the DOPF model. A genetic algorithm is used to determine the optimal solutions for controllable devices, in particular load tap changers, switched capacitors, and smart loads in the context of an energy management system for practical feeders, accounting for the fact that smart loads consumption should not be significantly affected by network constraints. Since the number of control variables in a realistic distribution power system is large, solving the DOPF for real-time applications is computationally expensive. Hence, to reduce computational times, a decentralized system with parallel computing nodes based on an SGCM system is proposed. Using a "MapReduce" model, the SGCM system runs the DOPF model, communicates between master and worker computing nodes, and sends/receives data among different parts of parallel computing system. Compared to a centralized approach, the proposed architecture is shown to yield better optimal solutions in terms of reducing energy losses and/or energy drawn from the substation within adequate practical run-times for a realistic test feeder.
The demand for plant-based meat analogs (PBMA) is on the rise as a strategy to sustain the food protein supply while mitigating environmental change. In addition to supplying essential amino acids ...and energy, food proteins are known sources of bioactive peptides. Whether protein in PBMA affords similar peptide profiles and bioactivities as real meat remains largely unknown. The purpose of this study was to investigate the gastrointestinal digestion fate of beef and PBMA proteins with a special focus on their potential as precursors of bioactive peptides. Results showed that PBMA protein showed inferior digestibility than that in beef. However, PBMA hydrolysates possessed a comparable amino acid profile to that of beef. A total of 37, 2420 and 2021 peptides were identified in the gastrointestinal digests of beef, Beyond Meat and Impossible Meat, respectively. The astonishingly fewer peptides identified from beef digest is probably due to the near-full digestion of beef proteins. Almost all peptides in Impossible Meat digest were from soy, whereas 81%, 14% and 5% of peptides in Beyond Meat digest were derived from pea, rice and mung proteins, respectively. Peptides in PBMA digests were predicted to exert a wide range of regulatory roles and were shown to have ACE inhibitory, antioxidant and anti-inflammatory activities, supporting the potential of PBMA as a source of bioactive peptides.
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