Production and purification of antioxidant peptides from a mungbean meal hydrolysate by Virgibacillus sp. SK37 proteinase

Recent advances in mung bean protein: From structure, function to application

With the surge in protein demand, the application of plant proteins has ushered in a new wave of research. Mung bean is a potential source of protein due to its high protein content (20-30 %). The nutrition, structure, function, and application of mung bean protein have always been a focus of attention. In this paper, these highlighted points have been reviewed to explore the potential application value of mung bean protein. Mung bean protein contains a higher content of essential amino acids than soybean protein, which can meet the amino acid values recommended by FAO/WHO for adults. Mung bean protein also can promote human health due to its bioactivity, such as the antioxidant, and anti-cancer activity. Meanwhile, mung bean protein also has well solubility, foaming, emulsification and gelation properties. Therefore, mung bean protein can be used as an antioxidant edible film additive, emulsion-based food, active substance carrier, and meat analogue in the food industry. It is understood there are still relatively few commercial applications of mung bean protein. This paper highlights the potential application of mung bean proteins, and aims to provide a reference for future commercial applications of mung bean proteins.

The Antioxidant Mechanism of Peptides Extracted from Tuna Protein Revealed Using a Molecular Docking Simulation

Tuna protein serves as a significant source of bioactive peptides, and its functional properties can be elucidated through predictive modeling, followed by experimental validation. In this study, the active polypeptides were obtained from tuna protein via enzymatic hydrolysis (TPP), and their peptide sequences were determined. Furthermore, the potential activity of these peptides was predicted, focusing on antioxidant peptides, and compared to the sequence library of known antioxidant peptides to identify common structural motifs. The accuracy of the prediction results was confirmed through in vitro antioxidant assays and molecular docking studies. We identified seven specific peptide segments derived from tuna protein that exhibit antioxidant potential, accounting for approximately 15% of all active peptides. Molecular docking and cell experiments were employed to provide compelling evidence for the presence of antioxidant peptides within tuna protein. This study not only lays a solid foundation for studying the structure of active peptides but also opens up a novel avenue for an expedited assessment of their properties.

From microbes to molecules: a review of microbial-driven antioxidant peptide generation

Oxidative stress, arising from excess reactive oxygen species (ROS) or insufficient antioxidant defenses, can damage cellular components, such as lipids, proteins, and nucleic acids, resulting in cellular dysfunction. The relationship between oxidative stress and various health disorders has prompted investigations into potent antioxidants that counteract ROS's detrimental impacts. In this context, antioxidant peptides, composed of two to twenty amino acids, have emerged as a unique group of antioxidants and have found applications in food, nutraceuticals, and pharmaceuticals. Antioxidant peptides are sourced from natural ingredients, mainly proteins derived from foods like milk, eggs, meat, fish, and plants. These peptides can be freed from their precursor proteins through enzymatic hydrolysis, fermentation, or gastrointestinal digestion. Previously published studies focused on the origin and production methods of antioxidant peptides, describing their structure-activity relationship and the mechanisms of food-derived antioxidant peptides. Yet, the role of microorganisms hasn't been sufficiently explored, even though the production of antioxidant peptides frequently employs a variety of microorganisms, such as bacteria, fungi, and yeasts, which are recognized for producing specific proteases. This review aims to provide a comprehensive overview of microorganisms and their proteases participating in enzymatic hydrolysis and microbial fermentation to produce antioxidant peptides. This review also covers endogenous peptides originating from microorganisms. The information obtained from this review might guide the discovery of novel organisms adept at generating antioxidant peptides.

Extraction, bioactive function and application of wheat germ protein/peptides: A review

The aging population and high incidence of age-related diseases are major global societal issues. Consuming bioactive substances as part of our diet is increasingly recognized as essential for ensuring a healthy life for older adults. Wheat germ protein has a reasonable peptide structure and amino acid ratio but has not been fully utilized and exploited, resulting in wasted wheat germ resources. This review summarizes reformational extraction methods of wheat germ protein/peptides (WGPs), of which different methods can be selected to obtain various WGPs. Interestingly, except for some bioactive activities found earlier, WGPs display potential anti-aging activity, with possible mechanisms including antioxidant, immunomodulatory and intestinal flora regulation. However, there are missing in vitro and in vivo bioactivity assessments of WGPs. WGPs possess physicochemical properties of good foamability, emulsification and water retention and are used as raw materials or additives to improve food quality. Based on the above, further studies designing methods to isolate particular types of WGPs, determining their nutritional and bioactive mechanisms and verifying their activity in vivo in humans are crucial for using WGPs to improve human health.

Bacillales: From Taxonomy to Biotechnological and Industrial Perspectives

For a long time, the genus Bacillus has been known and considered among the most applicable genera in several fields. Recent taxonomical developments resulted in the identification of more species in Bacillus-related genera, particularly in the order Bacillales (earlier heterotypic synonym: Caryophanales), with potential application for biotechnological and industrial purposes such as biofuels, bioactive agents, biopolymers, and enzymes. Therefore, a thorough understanding of the taxonomy, growth requirements and physiology, genomics, and metabolic pathways in the highly diverse bacterial order, Bacillales, will facilitate a more robust designing and sustainable production of strain lines relevant to a circular economy. This paper is focused principally on less-known genera and their potential in the order Bacillales for promising applications in the industry and addresses the taxonomical complexities of this order. Moreover, it emphasizes the biotechnological usage of some engineered strains of the order Bacillales. The elucidation of novel taxa, their metabolic pathways, and growth conditions would make it possible to drive industrial processes toward an upgraded functionality based on the microbial nature.

Unconventional microbial proteases as promising tools for the production of bioactive protein hydrolysates

Enzymatic hydrolysis is the most prominent strategy to release bioactive peptides from different food proteins and protein-rich by-products. Unconventional microbial proteases (UMPs) have gaining increased attention for such purposes, particularly from the 2010s. In this review, we present and discuss aspects related to UMPs production, and their use to obtain bioactive protein hydrolysates. Antioxidant and anti-hypertensive potentials, commonly evaluated through in vitro testing, are mainly reported. The in vivo bioactivities of protein hydrolysates and peptides produced through UMPs action are highlighted. In addition to bioactivities, enzymatic hydrolysis acts by modulating the functional properties of proteins for potential food uses. The compiled literature indicates that UMPs are promising biocatalysts to generate bioactive protein hydrolysates, adding up to commercially available enzymes. From the recent interest on this topic, continuous and in-depth research is needed to advance toward the applicability and commercial utility of both UMPs and obtained hydrolysates.

A review on processing methods and functions of wheat germ-derived bioactive peptides

Wheat germ protein is a potential resource to produce bioactive peptides. As a cheap, safe, and healthy nutritional factor, wheat germ-derived bioactive peptides (WGBPs) provide benefits and great potential for biomedical applications. The objective of this review is to reveal the current research status of WGBPs, including their preparation methods and biological functions, such as antibacterial, anti-tumor, immune regulation, antioxidant, and anti-inflammatory properties, etc. We also reviewed the information in terms of the preventive ability of WGBPs to treat serious infectious diseases, to offer their reference to further research and application. Opinions on future research directions are also discussed. Through the review of previous research, we find that there are still some scientific issues in the basic research and industrialization process of WGBPs that deserve further exploration. Firstly, based on current complex enzymolysis, the preparation and production of WGBPs need to be combined with other advanced technology to achieve efficient and large-scale production. Secondly, studies on the bioavailability, biosafety, and mechanism against different diseases of WGBPs need to be carried out in different in vitro and in vivo models. More human experimental evidence is also required to support its industrial application as a functional food and nutritional supplement.HighlightsThe purification and identification of wheat germ-derived bioactive peptides.The main biological activities and potential mechanisms of wheat germ hydrolysates/peptides.Possible absorption and transport pathways of wheat germ hydrolysate/peptide.Wheat germ peptide shows a variety of health benefits according to its amino acid sequence.Current food applications and future perspectives of wheat germ protein hydrolysates/peptide.

Enzymatic Hydrolysis of Broken Rice Protein: Antioxidant Activities by Chemical and Cellular Antioxidant Methods

Excessive reactive oxygen species (ROS) is an important cause of aging, and supplementing antioxidants through diet is one of the important ways to delay aging. Some studies have confirmed that rice protease hydrolysate has antioxidant activity, but was rarely been investigated on cells. Thus, commercial enzymes, alkaline enzyme, neutral enzyme, pepsin, chymotrypsin, and trypsin were selected to hydrolyze broken rice protein (BRP) to obtain the corresponding hydrolysates, which were A-broken rice protein hydrolysate (BRPH), N-BRPH, P-BRPH, C-BRPH, and T-BRPH, respectively. Then the antioxidant properties of BRPHs were evaluated by different chemical and cellular antioxidation. Molecular weight, peptide length distribution, and amino acid sequence were detected to insight into the antioxidant properties. Among BRPHs, the A-BRPH displayed the strongest hydroxyl radical scavenging activity (IC50 = 1.159 mg/ml) and metal ion-chelating activities (IC50 = 0.391 mg/ml). Furthermore, cellular antioxidation confirmed that A-BRPH significantly increased cell viability and inhibited the intracellular ROS release in both aging cells and cell-aging processes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) results revealed that peptides with molecular weight <14.5 KDa were produced by enzymatic hydrolysis. Additionally, A-BRPH rich in low molecular weight (<3 kDa) and short-length peptides with some specific amino acids, such as aromatic and hydrophobic amino acids, contributes to the antioxidant properties. This study provided theoretical to the utilization of broken rice and confirmed that A-BRPH could be used in new anti-aging food and health products for human consumption.

Selenium-containing soybean antioxidant peptides: Preparation and comprehensive comparison of different selenium supplements

Present study aimed to prepare and identify antioxidative peptides from selenium-containing soybeans, and to investigate their bioavailability and protective effects against oxidative stress-related diseases. Selenium-containing soybean antioxidative peptides (Mw < 1 kDa, SePPs) hydrolyzed by Neutrase and Alcalase reached the highest cellular antioxidant activity (EC50 value 320.5 ± 39.71 μg/L). SePPs could be efficiently absorbed through Caco-2 monolayer, and then significantly reverse the tumor necrosis factor-α (TNF-α)-induced inflammatory cytokine, phosphorylated c-Jun N-terminal kinases (p-JNK) and nuclear factor-kappa B (NF-κB) levels in EA. hy926 cells (p < 0.05). d-galactose-induced aging mice model showed that liver superoxidase dismutase (SOD) and glutathione peroxidase-1 (GPx-1) were enhanced, while aspartate aminotransferase (AST), alanine aminotransferase (ALT) and NF-κB were decreased by SePPs significantly (p < 0.05). SePPs could inhibit brain oxidative stress via regulating MAPK/NF-κB pathway. Comparing with Na2SeO3, selenomethionine (SeMet) and selenium-free peptides, SePPs was found to present synergistic effects of selenium and peptides in antioxidant activity.

Health Benefits of Antioxidative Peptides Derived from Legume Proteins with a High Amino Acid Score

Legumes such as soybean, chickpea, lentil, cowpea, and mung bean, are valuable sources of protein with a high amino acid score and can provide bioactive peptides. This manuscript presents a review on legume-derived peptides, focusing on in vitro and in vivo studies on the potential antioxidative activities of protein hydrolysates and their characterization, amino acid sequences, or purified/novel peptides. The health implications of legume-derived antioxidative peptides in reducing the risks of cancer and cardiovascular diseases are linked with their potent action against oxidation and inflammation. The molecular weight profiles and amino acid sequences of purified and characterized legume-derived antioxidant peptides are not well established. Therefore, further exploration of legume protein hydrolysates is necessary for assessing the potential applications of antioxidant-derived peptides in the functional food industry.

Separation, identification and molecular binding mechanism of dipeptidyl peptidase IV inhibitory peptides derived from walnut (Juglans regia L.) protein

Walnut protein was hydrolyzed with different proteases to evaluate the hydrolytic efficiency and dipeptidyl peptidase IV (DPP-IV) inhibitory activity in vitro. All of walnut protein hydrolysates (WPHs) exhibited DPP-IV inhibitory activity and Alcalase-derived hydrolysate (WPH-Alc) with better DPP-IV inhibitory activity of 33.90% (at 0.50 mg/mL) was subsequently separated by ultrafiltration and cation exchange chromatography on a SP Sephadex C-25 column. The results showed that fractions with lower molecular weight and higher basic amino acid residues possessed stronger DPP-IV inhibitory activity. Comparably, the obtained fraction B with the yield of 19.80% had the highest DPP-IV inhibitory activity of 76.19% at 0.25 mg/mL. Moreover, nine novel DPP-IV inhibitory peptides were identified using MALDI-TOF/TOF-MS. Molecular docking revealed the peptides could interact with DPP-IV through hydrogen bonds, salt bridges, hydrophobic interactions, π-cation bonds and π-π bonds. The walnut DPP-IV inhibitory peptides showed better stability with heating treatment, pH treatment, or in vitro gastrointestinal digestion.

Selenium-Containing Proteins/Peptides from Plants: A Review on the Structures and Functions

Selenium is an essential microelement required for biological processes. Traditional selenium supplements (selenite and selenomethionine mainly) remain concerns due to toxicity and bioavailability. In recent decades, biofortification strategies have been applied to produce selenium-enriched edible plants to address the challenges of superior nutritional quality requirements. Plant-derived selenium-containing proteins/peptides offer potential health benefits beyond the basic nutritional requirements of Se. Highly nucleophilic seleno-amino acids, special peptide sequences, and favorable bioavailability contribute to the biological activities of selenium-containing proteins/peptides, such as antioxidant, antihypertensive, anti-inflammatory, and immunomodulatory effects. However, their applications on a commercial scale are insufficient owing to the complexity of purification and identification techniques and the sparse information on bioavailability and metabolism. In this review, selenium status, structural features, bioactivities, structure-activity relationships, and bioavailability, as well as the mechanisms underlying the bioactivities and metabolism of plant-derived selenium-containing proteins/peptides, are summarized and discussed for their nutraceutical use.

Antioxidant Potential of Mung Bean (Vigna radiata) Albumin Peptides Produced by Enzymatic Hydrolysis Analyzed by Biochemical and In Silico Methods

The objective of this study was to investigate the biochemical antioxidant potential of peptides derived from enzymatically hydrolyzed mung bean (Vigna radiata) albumins using an 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assay, a ferrous ion chelating assay and an oxygen radical absorbance capacity (ORAC) assay. Peeled raw mung bean was ground into flour and mixed with buffer (pH 8.3, 1:20 w/v ratio) before being stirred, then filtered using 3 kDa and 30 kDa molecular weight cut-off (MWCO) centrifugal filters to obtain albumin fraction. The albumin fraction then underwent enzymatic hydrolysis using either gastrointestinal enzymes (pepsin and pancreatin) or thermolysin. Peptides in the hydrolysates were sequenced. The peptides showed low ABTS radical-scavenging activity (90-100 μg ascorbic acid equivalent/mL) but high ferrous ion chelating activity (1400-1500 μg EDTA equivalent/mL) and ORAC values (>120 μM Trolox equivalent). The ferrous ion chelating activity was enzyme- and hydrolysis time-dependent. For thermolysin hydrolysis, there was a drastic increase in ferrous ion chelating activity from t = 0 (886.9 μg EDTA equivalent/mL) to t = 5 min (1559.1 μg EDTA equivalent/mL) before plateauing. For pepsin-pancreatin hydrolysis, there was a drastic decrease from t = 0 (878.3 μg EDTA equivalent/mL) to t = 15 (138.0 μg EDTA equivalent/mL) after pepsin was added, but this increased from t = 0 (131.1 μg EDTA equivalent/mL) to t = 15 (1439.2 μg EDTA equivalent/mL) after pancreatin was added. There was no significant change in ABTS radical scavenging activity or ORAC values throughout different hydrolysis times for either the thermolysin or pepsin-pancreatin hydrolysis. Overall, mung bean hydrolysates produced peptides with high potential antioxidant capacity, being particularly effective ferrous ion chelators. Other antioxidant assays that use cellular lines should be performed to measure antioxidant capacity before animal and human studies.

Sturgeon hydrolysates alleviate DSS-induced colon colitis in mice by modulating NF-κB, MAPK, and microbiota composition

Sturgeon muscle byproduct collected after caviar production is usually not fully utilized, and sometimes may be discarded, thus causing a lot of waste. Yet dietary protein hydrolysates, which may be derived from sturgeon muscle, have been reported to have versatile beneficial biological activities. Studying the biological activities of sturgeon muscle-derived hydrolysates holds much promise for adding value to sturgeon. The current study aimed to study the therapeutic anti-inflammatory effects of sturgeon muscle-derived hydrolysates and the underlying mechanisms. The administration of sturgeon hydrolysates (SH) significantly decreased the severity of DSS-induced damage, evidenced by increased body weight, colon length, and decreased disease activity index (DAI) and histological scores. SH also inhibited myeloperoxidase (MPO) activity and reduced the serum levels of IL-6, IL-1β, and TNF-α. Western blotting results revealed that SH suppressed DSS-induced activation of the NF-κB and MAPK pathways in the colon. Furthermore, SH partially restored the alteration of the gut microbiota in colitic mice. SH increased the Bacteroidetes/Firmicutes ratio and the relative abundance of Ruminococcaceae, Porphyromonadaceae, and Bacteroidetes S24-7, while decreased the abundance of potentially harmful bacteria Erysipelotrichaceae and Enterococcaceae. These results suggest that SH inhibited DSS-induced colitis by regulating the NF-κB and MAPK pathways and modulating microbiota composition.

Exoenzyme-producing halophilic bacteria from the former Lake Texcoco: identification and production of n-butyl oleate and bioactive peptides

Halophilic bacterias from saline soil from former Lake Texcoco were isolated, identified based on 16 rRNA and tested to produce glucolytic, nucleolytic, proteolytic and lipolytic exoenzymes. The Bacillus, Virgibacillus, Kocuria, Salinicoccus, Gracilibacillus, Halobacillus, Tenuibacillus and Nesterekonia genera where identified. Lipase/eserases and proteases from Nesterenkonia sp. and Nesterenkonia aethiopica showed halotolerant characteristics and were selected to synthesize the oleochemical n-butyl oleate and antioxidant peptides from muscle protein of common carp (Cyprinus carpio), respectively. In organic media (2,2,4-Trimethylpentane), the lipase/esterases from Nesterenkonia sp. (0.6 U/mL) and N. aethiopica (1.2 U/mL) achieved a 62.7% and 53.2% of n-butyl oleate conversion, respectively. The protein hydrolysis from muscle of common carp (C. carpio) showed a degree of hydrolysis of 4.5 ± 0.2% and 2.8 ± 0.1% when proteases from Nesterenkonia sp. and N. aethiopica were used, respectively. Three peptidic fractions ranging molecular masses between 254 and 1002 Da [M + H] show antioxidant scavenging activity, and the principal fraction with a peptide of 547.3 Da [M + H] showed an inhibition of 37.7 ± 1.8% and 16.3 ± 0.6%, when 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) were used, respectively. These findings showed that the enzymatic battery of the halophilic bacteria from former lake Texcoco can be used in hydrolysis and synthesis of molecules with applications in different fields as food technology or bioenergy.

Bioactive peptides from brown rice protein hydrolyzed by bromelain: Relationship between biofunctional activities and flavor characteristics

This study evaluated the biological properties of peptides from brown rice protein hydrolyzed by bromelain (eb-RPH) in relation to flavor characteristic. The fractionation into peptides < 1 kDa was observed to improve the DPPH, ABTS, and hydroxyl radical-scavenging activities (0.19, 2.28, and 24.64 mM Trolox, respectively), angiotensin-converting enzyme (ACE)-inhibitory activity (IC₅₀ value of 0.20 ± 0.011 mg protein/mL), as well as bitter and umami tastes. The < 1 kDa fraction was further analyzed by liquid chromatography-electrospray ionization/mass spectrometry to identify amino acid sequence associated with biological activities and flavor characteristics. Eight peptides were identified. Most of the identified peptides contained features of previously reported ACE inhibitory and antioxidant peptides, especially peptide FGGSGGPGG and FGGGGAGAGG. Evaluation of flavor characteristics using BIOPEP database demonstrated that they had high occurrence frequencies of umami peptides (ESDVVSDL, GSGVGGAK, and SSVGGGSAG) and low Q-value (938.75 to 282.22), suggesting that these peptides may be used as a fortifying health ingredient with good taste. PRACTICAL APPLICATION: The fractionated brown rice protein hydrolysate (< 1 kDa) has the potential to serve as a functional food ingredient in nutraceutical food and beverage products that can provide health benefits with good taste. Information on amino acid composition and spatial conformation of peptide may aid us to better understand the molecular mechanisms involved in bioactivities and flavor of brown rice peptide for industrial applications.

Mung Bean Protein Hydrolysates Protect Mouse Liver Cell Line Nctc-1469 Cell from Hydrogen Peroxide-Induced Cell Injury

Mung bean is nutritious and rich in protein (19.5%–33.1%). However, there are few studies on mung bean protein active peptides so the mung bean protein hydrolysates (MBPHs) were investigated for evaluating their ability to clear intracellular reactive oxygen species (ROS) and regulating the ability of antioxidant enzymes on NCTC-1469 cells. Results showed that MBPHs, MBPHs-I (molecular weight < 3 kDa), MBPHs-II (molecular weight between 3 and 10 kDa), and MBPHs-III (molecular weight > 10 kDa) could all improve the survival rate of cells compared with the model group. MBPHs, MBPHs-I, and MBPHs-II could significantly decrease the content of lactate dehydrogenase (LDH) and reduce the generation of malonaldehyde (MDA) at a concentration of 0.4 mg/mL. Regarding the intracellular ROS, the result showed that MBPHs-I significantly reduced the production of ROS (from 58.3% to 26.6%) and had a dose-dependent relationship. In addition, the amino acid analysis showed that MBPHs-I had a balanced amino acid composition. MBPHs-I is rich in lysine but was deficient in cereals. Therefore, the hydrophobic and aromatic amino acids in MBPHs-I were high, which could improve its antioxidant activity. According to the results, MBPHs-I was the best and most potent natural antioxidant and it can contribute to drug development and medical application.

Purification and Identification of Antioxidant Alcalase-Derived Peptides from Sheep Plasma Proteins

In this study, sheep plasma was submitted to Alcalase-hydrolysis and peptides with better antioxidant properties measured through both the ferric-reducing antioxidant power (FRAP) and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability assays were isolated and identified. After hydrolysate ultrafiltration and semi-preparative reverse-phase high-performance liquid chromatography, nine fractions (F1-F9) were obtained, with the two first (F1 and F2) showing the greatest antioxidant potential. These two fractions were further separated by the AKTA purifier system to generate four (F1-1-F1-4) and five (F2-1-F2-5) fractions, respectively, with two of them (F1-2 and F2-1) exhibiting appreciable FRAP activity and DPPH radical scavenging ability. Using liquid chromatography-tandem mass spectrometry, three antioxidant peptides were identified. From their amino acid sequences (QTALVELLK, SLHTLFGDELCK, and MPCTEDYLSLILNR), which include amino acids that have been previously reported as key contributors to the peptide antioxidant properties, it can be maintained that they come mainly from serum albumin. These results suggested that the sheep plasma protein can be considered as a good source of antioxidant peptides and bring forth new possibilities for the utilization of animal blood by-products.

Four Antioxidant Peptides from Protein Hydrolysate of Red Stingray (Dasyatis akajei) Cartilages: Isolation, Identification, and In Vitro Activity Evaluation

In the work, water-soluble proteins of red stingray (Dasyatis akajei) cartilages were extracted by guanidine hydrochloride and hydrolyzed using trypsin. Subsequently, four antioxidant peptides (RSHP-A, RSHP-B, RSHP-C, and RSHP-D) were isolated from the water-soluble protein hydrolysate while using ultrafiltration and chromatographic techniques, and the amino acid sequences of RSHP-A, RSHP-B, RSHP-C, and RSHP-D were identified as Val-Pro-Arg (VPR), Ile-Glu-Pro-His (IEPH), Leu-Glu-Glu--Glu-Glu (LEEEE), and Ile-Glu-Glu-Glu-Gln (IEEEQ), with molecular weights of 370.46 Da, 494.55 Da, 647.64 Da, and 646.66 Da, respectively. VPR, IEPH, LEEEE, and IEEEQ exhibited good scavenging activities on the DPPH radical (EC50 values of 4.61, 1.90, 3.69, and 4.01 mg/mL, respectively), hydroxyl radical (EC50 values of 0.77, 0.46, 0.70, and 1.30 mg/mL, respectively), superoxide anion radical (EC50 values of 0.08, 0.17, 0.15, and 0.16 mg/mL, respectively), and ABTS cation radical (EC50 values of 0.15, 0.11, 0.19, and 0.18 mg/mL, respectively). Among the four isolated antioxidant peptides, IEPH showed the strongest reducing power and lipid peroxidation inhibition activity, but LEEEE showed the highest Fe2+-chelating ability. The present results suggested that VPR, IEPH, LEEEE, and IEEEQ might have the possibility of being an antioxidant additive that is used in functional food and pharmaceuticals.

Assessment of antioxidant properties of membrane ultrafiltration peptides from mungbean meal protein hydrolysates

BACKGROUND

Bioactive peptides can prevent damage associated with oxidative stress in humans when consumed regularly. Recently, peptides have attracted immense interest because of their beneficial functional properties, safety and little or no side effects when used at high concentration. Most antioxidant peptides are small in size, less than 1 kDa, and contains a high proportion of hydrophobic amino acid. Particularly, tyrosine, leucine, alanine, isoleucine, valine, lysine, phenyalanine, cysteine, methionine and histidine in peptide chain exhibited high antioxidant activity. Mungbean meal protein (MMP) is highly abundant in hydrophobic amino acids. It indicated that MMP might be a good source of antioxidants. Therefore, the objectives were to optimize the conditions used to generate mungbean meal protein hydrolysate (MMPH) with antioxidant activity from bromelain and to investigate the antioxidant activities of different molecular weight (MW) peptide fraction.

METHODS

Response Surface Methodology (RSM) was used for screening of the optimal conditions to produce MMPH. After that MMPH was fractionated using ultrafiltration membranes with different MW distributions. Crude-MMPH and four fractions were investigated for five antioxidant activities: 2,2,1-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, superoxide, ferric reducing antioxidant power (FRAP) and metal ion chelation activity.

RESULTS

The optimal condition to produce the MMPH was 15% (w/w) of bromelain and hydrolysis time for 12 h which showed the greatest DPPH and ABTS radical scavenging activity. After mungbean protein from optimal condition was separated based on different molecular weight, the DPPH radical scavenging activity was the highest for the F4 (less than 1 kDa) peptide fraction. Metal ion chelating activity was generally weak, except for the F4 that had a value of 43.94% at a protein concentration of 5 mg/mL. The F4 also exhibited high hydroxyl and superoxide activities (54 and 65.1%), but moderate activity for ferric reducing antioxidant power (0.102 mmole Fe2+/g protein) compared to other peptide fractions and crude-MMPH. Molecular weight and amino acid were the main factors that determined the antioxidant activities of these peptide fractions. Results indicated that F4 had strong antioxidant potentials.

DISCUSSION

The lowest MW fraction (less than 1 kDa) contributed to the highest DPPH, superoxide, hydroxyl and metal chelation activity because influence of low MW and high content of hydrophobic amino acid in peptide chain. Results from this study indicated that MMPH peptides donate protons to free radicals because they had significantly high DPPH value compared to superoxide, hydroxyl and FRAP, which reactions were electron donation. Moreover, MMPH peptides had the ability to inhibit transition metal ions because of highly abundant glutamic acid and aspartic acid in peptide chain.

Comparisons of Processing Stability and Antioxidant Activity of the Silkworm Pupae Protein Hydrolysates by Spray-dry and Freeze-dry

Silkworm pupae protein (SPP) was pretreated by different processing (heat/alkali/pepsin) and then hydrolyzed by five proteases (trypsin/flavorzyme/papain/protamex/alcalase), respectively. It was found that the combination of heat pretreatment and alkali pretreatment followed by enzymatic hydrolysis with trypsin and flavorzyme could remarkably improve the protein recovery. The hydrolysates obtained from silkworm pupae protein hydrolyzed with trypsin and flavorzyme were stable at the pH range of 4.0–8.0, remaining 95 % of its original reducing power and 90 % of its OH• scavenging activity. However, they were susceptible to alkaline treatments (pH > 10.0) and lost >30 % of their antioxidant activities. Pasteurization (65 °C × 30 min) or autoclaving sterilization (121 °C × 20 min) did not show notable effects on the antioxidant activities. It was concluded that silkworm pupae protein hydrolysates (SPPH) were better to be applied in either neutral or acidic food system rather than in alkaline conditions.

Volatile flavour compounds, sensory characteristics and antioxidant activities of mungbean meal protein hydrolysed by bromelain

Enzymatic mungbean meal protein hydrolysate (eb-MPH) is a novel natural flavour/antioxidant source. A 15% bromelain (w/w) concentration with a hydrolysis time of 12 h was the optimum conditions to produce eb-MPH, which showed the greatest antioxidant activities and sensory characteristics. eb-MPH was composed of oligopeptides that had low molecular weight (< 10 kDa) as well as surface hydrophobicity and high content of hydrophobic amino acids. eb-MPH contributed to DPPH (80) and ABTS (95%) scavenging activities and to savoury/sweet flavour volatile compounds (3-methyl-butanal, furfural and benzaldehyde), bouillon odour, sweet odour, chicken odour, meaty odour, moderate bitter taste and umami. In addition, principal component analysis (PCA) showed that 72.87% of the total variance confirmed the correlation between DH, S₀, DPPH, ABTS, sensory characteristics and volatile flavour compounds. These results suggested that eb-MPH can be used as a natural food flavouring agent and antioxidant.

A novel multi-biofunctional protein from brown rice hydrolysed by endo/endo-exoproteases

Brown rice, which is a less allergenic food grain and contains essential amino acids, was hydrolysed by bromelain and PROTEASE FP51® to improve its functionalities and taste for food applications. The hydrolysate prepared by bromelain (eb-RPH) had high protein solubility, surface hydrophobicity, low molecular weight peptides, hydrophobic amino acids (leucine, valine and glycine) and flavor amino acids (glutamic acid and aspartic acid). The eb-RPH exhibited higher 1,1-diphenyl-2-picrylhydrazyl (DPPH˙) and 2,2'-azino-bis 3-ethylbenzthiazoline-6-sulfonic (ABTS˙(+)) radical-scavenging activities of 76.62% and 52.96%, respectively, and possessed a better foaming capacity (221.76%) and emulsifying capacity (32.34%) than the hydrolysate prepared by PROTEASE FP51® (ep-RPH) did. The eb-RPH gave the desired taste, which is attributed to volatile flavor compounds (benzaldehyde, benzeneacetaldehyde and 2-acetyl-1-pyrroline) and non-volatile flavor compounds, such as monosodium glutamate, 5'-guanosine monophosphate and 5'-inosine monophosphate (0.07, 0.03 and 0.05 mg mL(-1), respectively). Brown rice peptides generated by bromelain were novel bioactive peptides with multifunctional properties.

Antioxidants: Characterization, natural sources, extraction and analysis

Recently many review papers regarding antioxidants from different sources and different extraction and quantification procedures have been published. However none of them has all the information regarding antioxidants (chemistry, sources, extraction and quantification). This article tries to take a different perspective on antioxidants for the new researcher involved in this field. Antioxidants from fruit, vegetables and beverages play an important role in human health, for example preventing cancer and cardiovascular diseases, and lowering the incidence of different diseases. In this paper the main classes of antioxidants are presented: vitamins, carotenoids and polyphenols. Recently, many analytical methodologies involving diverse instrumental techniques have been developed for the extraction, separation, identification and quantification of these compounds. Antioxidants have been quantified by different researchers using one or more of these methods: in vivo, in vitro, electrochemical, chemiluminescent, electron spin resonance, chromatography, capillary electrophoresis, nuclear magnetic resonance, near infrared spectroscopy and mass spectrometry methods.

Effect of fermentation on the antioxidant activity in plant-based foods

This study provides an overview of the factors that influence the effect of fermentation on the antioxidant activity and the mechanisms that augment antioxidative activities in fermented plant-based foods. The ability of fermentation to improve antioxidant activity is primarily due to an increase in the amount of phenolic compounds and flavonoids during fermentation, which is the result of a microbial hydrolysis reaction. Moreover, fermentation induces the structural breakdown of plant cell walls, leading to the liberation or synthesis of various antioxidant compounds. These antioxidant compounds can act as free radical terminators, metal chelators, singlet oxygen quenchers, or hydrogen donors to radicals. The production of protease, α-amylase and some other enzymes can be influenced by fermentation that may have metal ion chelation activity. Because the mechanisms that affect antioxidant activity during fermentation are extremely varied, further investigation is needed to establish the precise mechanisms for these processes.

Isolation and characterization of collagen and antioxidant collagen peptides from scales of croceine croaker (Pseudosciaena crocea)

Acid soluble collagen (ASC) from scales of croceine croaker (ASC-C) was successfully isolated with the yield of 0.37% ± 0.08% (dry weight basis), and characterized as type I collagen on the basis of amino acid analysis and electrophoretic pattern. The antioxidant hydrolysate of ASC-C (ACH) was prepared through a two-stage in vitro digestion (4-h trypsin followed by 4-h pepsin), and three antioxidant peptides (ACH-P1, ACH-P2, and ACH-P3) were further isolated from ACH using ultrafiltration, gel chromatography, and RP-HPLC, and their amino acid sequences were identified as GFRGTIGLVG (ACH-P1), GPAGPAG (ACH-P2), and GFPSG (ACH-P3). ACH-P1, ACH-P2, and ACH-P3 showed good scavenging activities on hydroxyl radical (IC₅₀ 0.293, 0.240, and 0.107 mg/mL, respectively), DPPH radical (IC₅₀ 1.271, 0.675, and 0.283 mg/mL, respectively), superoxide radical (IC₅₀ 0.463, 0.099, and 0.151 mg/mL, respectively), and ABTS radical (IC₅₀ 0.421, 0.309, and 0.210 mg/mL, respectively). ACH-P3 was also effectively against lipid peroxidation in the model system. The antioxidant activities of three collagen peptides were due to the presence of hydrophobic amino acid residues within the peptide sequences. The collagen peptides might be used as antioxidant for the therapy of diseases associated with oxidative stress, or reducing oxidative changes during storage.