Identification of umami peptides based on virtual screening and molecular docking from Atlantic cod (Gadus morhua)

The molecular reactive pathway between lipoxygenase and lipase and reactive species generated in dielectric barrier discharge atmospheric cold plasma: An investigation using molecular docking

The molecular docking was explored to study the interactions between reactive species generated by cold plasma and the enzymes lipoxygenase (LOX) and lipase (LPS), with the aim of elucidating the molecular mechanisms governing these interactions. Molecular docking results suggest that both LOX and LPS are primarily involved in hydrogen bonding interactions with the seven reactive species. The key binding sites for LOX and LPS were identified as Ile 663 and Glu 188, respectively. Notably, the lowest docking energy was observed between LOX and NO (-13.75 kcal/mol), whereas for LPS, it is between LPS and NO3 (-12.08 kcal/mol). Increased treatment voltage and time resulted in higher inactivation levels, with LPS exhibiting higher residual activity compared to LOX. When the voltage was 75 kV and the time was 120 s, the residual activities of LOX and LPS were 42.88% and 56.77%, respectively. Consequently, the results enhance our understanding of the mechanisms underlying the inhibition of enzyme activity by reactive species generated by cold plasma. Moreover, cold plasma may serve as a novel preservation technology for inhibiting lipid oxidation of food by controlling enzyme activity.

Taste characterization and molecular docking study of novel umami flavor peptides in Yanjin black bone Chicken meat

Five polypeptides with a potential umami taste were isolated and purified from Yanjin black bone chicken. However, the flavor characteristics and umami mechanism have not been clarified. The umami properties of these five peptides were investigated in this work using a range of analytical techniques, computer simulation, and sensory evaluation. HE-10 and TP-7 exhibited the strongest umami flavors. Furthermore, dose-response experiments showed that the umami peptides enhanced umami by generating peptide mineral chelates. Environmental scanning electron microscopy (ESEM) microstructural analyses supported this finding. The molecular docking results indicated that the five polypeptides bind to four critical amino acid residues, namely Glu217, Glu148, Asp216, and His145, of the T1R1/T1R3 receptor. The binding occurred through van der Waals, electrostatic interactions, hydrogen bonding, and hydrophobic interactions. The main surface forces implicated include aromatic interactions, hydrogen bonding, hydrophilicity, and solvent accessibility.

Screening and identification of novel umami peptides from yeast proteins: Insights into their mechanism of action on receptors T1R1/T1R3

This study aimed to unravel the peptide profiles of six distinct yeast protein samples and identify novel umami peptides within them. Peptide characteristics analysis support the proposition that yeast protein peptide pools represent exceptional reservoirs of umami peptides. Nine potential umami peptides were screened using the iUmami_SCM, UMPred-FRL, Umami_YYDS, Umami-MRNN, Innovagen, Expasy-ProtParam, and ToxinPred tools. Peptides AGVEDVY, LFEQHPEYRK, AFDVQ, GPTVEEVD, NVVAGSDLR, ATNGSR, and VEVVALND (1 mg/mL) were confirmed to possess umami taste, and the first five peptides exhibited significant umami-enhancing effects on 0.35 % monosodium glutamate. Molecular docking indicated that peptide residues His, Arg, Tyr, Asp, Gln, Thr, Ser, and Glu primarily bound to His71, Ser107/109/148, Asp147/218, and Arg277 of T1R1 and Ser104/146, His145, Asp216, Tyr218, and Ala302 of T1R3 through hydrogen bonds. This study enriches the umami peptide repository for potential food additive use and establishes a theoretical foundation for exploring taste compounds in yeast proteins and their broader applications.

Identification of salty peptides from enzymolysis extract of oyster by peptidomics and virtual screening

Salty peptide as an important sodium substitute, which could reduce the risk of cardiovascular disease caused by excessive sodium intake. In this study, novel salty peptides were prepared and identified from enzymolysis extract of oysters by peptitomic identification, virtual screening and solid phase synthesis. Additionally, molecular simulation was used to study the taste mechanism of salty peptides. 316 peptides were identified in the enzymatic hydrolysates of oysters. 6 peptides, selected through virtual screening, were synthesized using solid-phase synthesis, and EK, LFE, LEY and DR were confirmed to possess a pleasing salty taste through electronic tongue evaluation. Molecular docking results indicated that these 4 peptides could enter the binding pocket within the transmembrane channel-like 4 (TMC4) cavity, wherein salt bridges, hydrogen bonds and attractive charges were the main binding forces. This study provides a rapid screening method for salty peptides in sea food products but possibly applied for other sources.

Effect of ultrasound on the characterization and peptidomics of foxtail millet bran protein hydrolysates

Protein hydrolysates have attracted much attention for their high biological activity and are a crucial product form for the utilization of foxtail millet bran by-products. In this study, changes in the structure, functionality, activity and peptide profile of foxtail millet bran protein hydrolysates (FMBPHs) at different ultrasound powers (0 - 600 W) were investigated. The results showed that ultrasound promoted the transformation of α-helix and β-sheet to random coils and β-turn, and the exposure of hydrophobic groups and sulfhydryl groups in FMBPHs. The average particle size of the samples decreased, and the absolute value of the ζ-potential increased significantly. Simultaneously, smaller porous particles and loose fragments appeared on the surface of FMBPHs when the ultrasonic power was increased to 450 W. Additionally, 450 W ultrasound treatment improved solubility, foaming properties, emulsifying properties, thermal stability of FMBPHs. The DPPH, ABTS and hydroxyl radical scavenging ability (IC50, 2.65, 1.06 and 3.02 mg/mL), Fe2+ chelating activity (IC50, 2.62 mg/mL), and reducing power of the samples were also enhanced. The peptidomics results demonstrated that ultrasonication increased the number of active peptides in the hydrolysate, and the relative abundance of 17 active peptides was obviously elevated at 450 W. Peptide map analysis showed that ultrasound-induced structural modifications affected the peptide profiles of Ubiquitin-like domain-containing protein, Cupin type-1 domain-containing protein, 40S ribosomal protein S19, and Oleosin 1, showing changes in the abundance of certain peptides, which may be related to changes in the characterization of FMBPHs.

Novel dual-pathogen multi-epitope mRNA vaccine development for Brucella melitensis and Mycobacterium tuberculosis in silico approach

Brucellosis and Tuberculosis, both of which are contagious diseases, have presented significant challenges to global public health security in recent years. Delayed treatment can exacerbate the conditions, jeopardizing patient lives. Currently, no vaccine has been approved to prevent these two diseases simultaneously. In contrast to traditional vaccines, mRNA vaccines offer advantages such as high efficacy, rapid development, and low cost, and their applications are gradually expanding. This study aims to develop multi-epitope mRNA vaccines argeting Brucella melitensis and Mycobacterium tuberculosis H37Rv (L4 strain) utilizing immunoinformatics approaches. The proteins Omp25, Omp31, MPT70, and MPT83 from the specified bacteria were selected to identify the predominant T- and B-cell epitopes for immunological analysis. Following a comprehensive evaluation, a vaccine was developed using helper T lymphocyte epitopes, cytotoxic T lymphocyte epitopes, linear B-cell epitopes, and conformational B-cell epitopes. It has been demonstrated that multi-epitope mRNA vaccines exhibit increased antigenicity, non-allergenicity, solubility, and high stability. The findings from molecular docking and molecular dynamics simulation revealed a robust and enduring binding affinity between multi-epitope peptides mRNA vaccines and TLR4. Ultimately, Subsequently, following the optimization of the nucleotide sequence, the codon adaptation index was calculated to be 1.0, along with an average GC content of 54.01%. This indicates that the multi-epitope mRNA vaccines exhibit potential for efficient expression within the Escherichia coli(E. coli) host. Analysis through immune modeling indicates that following administration of the vaccine, there may be variation in immunecell populations associated with both innate and adaptive immune reactions. These types encompass helper T lymphocytes (HTL), cytotoxic T lymphocytes (CTL), regulatory T lymphocytes, natural killer cells, dendritic cells and various immune cell subsets. In summary, the results suggest that the newly created multi-epitope mRNA vaccine exhibits favorable attributes, offering novel insights and a conceptual foundation for potential progress in vaccine development.

Discrimination and evaluation of commercial salmons by low-molecule-weight compounds: Oligopeptides and phosphatides

In this study, the overall sensory characteristics and low-molecule-weight compounds were analyzed to achieve the discrimination of different commercial salmons and investigate the salmon's sensory and nutritional quality. The results showed that above the overall sensory properties, O. mykiss, S. salar, and O. kisutch were the most satisfied salmons by the panel with the desirable texture and flavor, which displayed a large potential for growth in the consumption market. The alcohols and sulfur compounds were key volatile compounds contributing to typical aroma of O. masou and O. gorbuscha, response higher than others by 147% to 167%. The oligopeptides and phospholipids in salmon could be used as biomarkers for discrimination of these salmon. Oligopeptides were also closely related to the taste quality of salmon. Seventeen oligopeptides showed potential umami activity based on molecular docking results, especially Arg-Val and Ser-Asn, which were the key tastants contributing to the umami of salmon.

Identification and screening of umami peptides from skipjack tuna (Katsuwonus pelamis) hydrolysates using EAD/CID based micro-UPLC-QTOF-MS and the molecular interaction with T1R1/T1R3 taste receptor

In this study, the enzymatic hydrolysates of skipjack tuna, Katsuwonus pelamis, were purified by ultrafiltration and further identified through micro-ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (micro-UPLC-QTOF-MS). The potential umami peptides were identified using both conventional collision-induced dissociation (CID) and novel electron-activated dissociation (EAD) fragmentation techniques. Nine novel umami peptides with iUmami-SCM > 588 were screened. Sensory evaluation and electronic tongue analysis were performed to confirm the taste characteristics of the umami peptides, indicating that these umami peptides all exhibited varying degrees of umami taste. Molecular docking and molecular dynamics simulation were utilized to investigate the interaction with T1R1/T1R3 taste receptors. The docking results revealed that Asp234, Ser23, Glu231, and Ile237 appeared most frequently in all docking sites and formed stable complexes through hydrogen bonding and electrostatic interactions. Furthermore, molecular dynamics simulation allowed for a more comprehensive analysis of their interactions within a dynamic environment, providing a deeper understanding of the umami perception mechanism involving umami peptides and receptors.

Chitosan and inulin synergized with Lactiplantibacillus plantarum LPP95 to improve the quality characteristics of low-salt pickled tuber mustard

Low-salt pickled vegetables are in line with a healthier diet, yet ensuring consistent quality of such products is challenging. In this study, low-salt tuber mustard pickles fermented with Lactiplantibacillus plantarum LPP95 in the presence of chitosan and inulin were analyzed over a 30-day period, and quality changes were evaluated. Total acid productions along with high bacterial counts (106 CFU/mL) were observed in the initial 20 days during indoor storage temperature, in which the reduced fiber aperture was found significantly lead to an increase in crispness (16.94 ± 1.87 N) and the maintenance of a low nitrate content (1.23 ± 0.01 mg/kg). Moreover, the combined pickling treatment resulted in higher malic acid content, lower tartaric acid content, and a decrease in the content of bitter amino acids (e.g., isoleucine and leucine), thus leading to an increase in the proportion of sweet amino acids. Additionally, combined pickling led to the production of unique volatile flavor compounds, especially the distinct spicy flavor compounds isothiocyanates. Moreover, the combined pickling treatment resulted in an increase in the abundance of Lactiplantibacillus and promoted microbial diversity within the fermentation system. Thus, the synergistic effect among chitosan, inulin, and L. plantarum LPP95 significantly enhanced the quality of pickles. The study offers a promising strategy to standardize the quality of low-salt fermented vegetables.

High-throughput discovery of umami peptides from pork bone and elucidation of their molecular mechanism for umami taste perception

This study endeavored to high-throughput identify umami peptides from pork bone. Pork bone protein extracts were hydrolyzed using proteinase K and papain, enzymes selected through computational proteolysis of pork type I collagen under the controlled conditions predicted by umami intensity-guided response surface analysis. Peptide sequences (GVNAMLRK, HWDRSNWF, PGRGCPGN, NLRDNYRF, PGWETYRK, GPGCKAGL, VAQWRKCL, GPTAANRM) in hydrolysates were virtually screened as potential umami peptides. Sensory evaluation confirmed that six of these peptides demonstrate a progressive increase in umami intensity. Molecular docking revealed that hydrophilic amino acids in umami peptides predominantly formed hydrogen bonds with T1R1/T1R3. Specifically, residues Thr, Asn, Lys, Ser and Glu of peptides mainly interacted with Ser107/148/276 of T1R1, and residues Tyr, Arg and Asp played crucial roles in binding to the Ser104/146 and His145 of T1R3. This study offers insights into the high-value utilization of pork bones and guides the development of umami peptides in various food proteins.

Identification of Novel Umami Peptides from Yeast Protein through Enzymatic, Sensory, and In Silico Approaches

This study aimed to rapidly develop novel umami peptides using yeast protein as an alternative protein source. Yeast protein hydrolysates exhibiting pronounced umami intensity were produced using flavorzyme under optimum conditions determined via a sensory-guided response surface methodology. Six out of 2138 peptides predicted to possess umami taste by composite machine learning and assessed as nontoxic, nonallergenic, water-soluble, and stable using integrated bioinformatics were screened as potential umami peptides. Sensory evaluation results revealed these peptides exhibited multiple taste attributes (detection threshold: 0.37 ± 0.10-1.1 ± 0.30 mmol/L), including umami. In light of the molecular docking outcomes, it is inferred that hydrogen bond, hydrophobic, and electrostatic interactions enhanced the theoretically stable binding of peptides to T1R1/T1R3, with their contributions gradually diminishing. Hydrophilic amino acids within T1R1/T1R3, especially Ser, may play a particularly pivotal role in binding with umami peptides. Future research will involve establishing heterologous cell models expressing T1R1 and T1R3 to delve into the cellular physiology of umami peptides. Peptide sequences (FADL, LPDP, and LDIGGDF) also had synergistic saltiness-enhancing effects; to overcome the limitation of not investigating the saltiness enhancement mechanism, comprehensive experiments at the molecular and cellular levels will also be conducted. This study offers a rapid umami peptide development framework and lays the groundwork for exploring yeast protein taste compounds.

Identification of flavor peptides based on virtual screening and molecular docking from Hypsizygus marmoreuss

Hypsizygus marmoreuss is an under-explored source of flavor peptides that can enhance the flavor of NaCl or MSG, allowing products to be reformulated in line with reduction policies. This study utilized advanced techniques, including UPLC-Q-TOF MS/MS and molecular docking, to identify H. marmoreuss peptides. Sensory evaluations revealed 10 peptides with pronounced umami flavors and seven with dominantly salty tastes. VLPVPQK scored highest for umami intensity (5.2), and EGNPAHQK for salty intensity (6.2). Further investigation influenced by 0.35 % MSG or 0.35 % NaCl exposed peptides with elevated umami and salty thresholds. LDSPATPEK, VVEGEPSLK, and QKLPEKPER had umami-enhancing thresholds of 0.18, 0.18, and 0.35 mM, while LDSPATPEK and VVEGEPSLK had similar thresholds for salt (0.09 mM). Molecular docking revealed that taste receptor proteins interacted with umami peptides through hydrogen, carbon-hydrogen, alkyl, and van der Waals forces. Specific amino acids in the umami receptor T1R1 had roles in bonding with umami peptides through hydrogen and carbon-hydrogen interactions. In conclusion, molecular docking proved to be an effective and efficient method for flavor peptide screening. Further, this study demonstrated that flavor peptides from H. marmoreuss had the capacity to enhance NaCl and MSG flavours and might be useful tools for reformulation, reducing salt and MSG contents.

Sacha Inchi (Plukenetia volubilis L.) Protein Hydrolysate as a New Ingredient of Functional Foods

Sacha inchi (Plukenetia volubilis L.) is an under-exploited crop with great potential due to its nutritional and medicinal characteristics. A Sacha inchi protein isolate (SII), obtained from defatted Sacha inchi flour (SIF), was hydrolyzed by Bioprotease LA 660 under specific conditions. The hydrolysates were characterized chemically, and their digestibility and antioxidant capacity were evaluated by in vitro cell-free experiments to select the hydrolysate with major antioxidant activity. Sacha inchi protein hydrolysate at 20 min (SIH20B) was selected, and the anti-inflammatory capacity was evaluated by RT-qPCR and ELISA techniques, using two different doses in monocytes THP-1 stimulated with lipopolysaccharide (LPS). The results obtained showed that the in vitro administration of SIH20B down-regulated the TNF-α gene and reduced the release of this cytokine, whereas the anti-inflammatory cytokines IL-10 and IL-4 were up-regulated in LPS-stimulated monocytes and co-administrated with SIH20B. The peptides contained in SIH20B were identified, and the 20 more relatively abundant peptides with a mass by 1 kDa were subjected to in silico analysis to hypothesize those that could be responsible for the bioactivity reported in the hydrolysate. From the identified peptides, the peptides AAGALKKFL and LGVKFKGGL, among others, are proposed as the most biologically actives. In conclusion, SIH20B is a novel, natural source of high-value-added biopeptides that could be used as an ingredient in formulations of food or nutraceutical compounds.

Food-derived peptides unleashed: emerging roles as food additives beyond bioactivities

Innovating food additives stands as a cornerstone for the sustainable evolution of future food systems. Peptides derived from food proteins exhibit a rich array of physicochemical and biological attributes crucial for preserving the appearance, flavor, texture, and nutritional integrity of foods. Leveraging these peptides as raw materials holds great promise for the development of novel food additives. While numerous studies underscore the potential of peptides as food additives, existing reviews predominantly focus on their biotic applications, leaving a notable gap in the discourse around their abiotic functionalities, such as their physicochemical properties. Addressing this gap, this review offers a comprehensive survey of peptide-derived food additives in food systems, accentuating the application of peptides' abiotic properties. It furnishes a thorough exploration of the underlying mechanisms and diverse applications of peptide-derived food additives, while also delineating the challenges encountered and prospects for future applications. This well-time review will set the stage for a deeper understanding of peptide-derived food additives.

Exploring the Relationship between Small Peptides and the T1R1/T1R3 Umami Taste Receptor for Umami Peptide Prediction: A Combined Approach

Umami peptides are known for enhancing the taste experience by binding to oral umami T1R1 and T1R3 receptors. Among them, small peptides (composed of 2-4 amino acids) constitute nearly 40% of reported umami peptides. Given the diversity in amino acids and peptide sequences, umami small peptides possess tremendous untapped potential. By investigating 168,400 small peptides, we screened candidates binding to T1R1/T1R3 through molecular docking and molecular dynamics simulations, explored bonding types, amino acid characteristics, preferred binding sites, etc. Utilizing three-dimensional molecular descriptors, bonding information, and a back-propagation neural network, we developed a predictive model with 90.3% accuracy, identifying 24,539 potential umami peptides. Clustering revealed three classes with distinct logP (-2.66 ± 1.02, -3.52 ± 0.93, -2.44 ± 1.23) and asphericity (0.28 ± 0.12, 0.26 ± 0.11, 0.25 ± 0.11), indicating significant differences in shape and hydrophobicity (P < 0.05) among potential umami peptides binding to T1R1/T1R3. Following clustering, nine representative peptides (CQ, DP, NN, CSQ, DMC, TGS, DATE, HANR, and STAN) were synthesized and confirmed to possess umami taste through sensory evaluations and electronic tongue analyses. In summary, this study provides insights into exploring small peptide interactions with umami receptors, advancing umami peptide prediction models.

Exploring the interaction mechanism of chlorogenic acid and myoglobin: Insights from structure and molecular dynamics simulation

This study focused on non-covalent complex of myoglobin-chlorogenic acid (Mb-CA) and the changes in conformation, oxidation, and microstructure induced by varying concentrations of CA (10-40 μmol/g Mb). Employing molecular docking and dynamics simulations, further insights into the interaction between Mb and CA were obtained. The findings revealed that different CA concentrations enhanced Mb's thermal stability, while diminishing particle size, solubility, and relative content of metmyoglobin (MetMb%). The optimal interaction occurred at 40 μmol/g Mb. Furthermore, CA exhibited static quenching of Mb, with thermodynamic analysis confirming a 1:1 complex formation. These insights deepen our understanding of interaction between Mb and CA, providing valuable clarity.

Novel Umami Peptides from Mushroom (Agaricus bisporus) and Their Umami Enhancing Effect via Virtual Screening and Molecular Simulation

This study aimed to identify novel umami peptides in Agaricus bisporus and investigate their umami enhancing effect. We virtually screened 155 potential umami peptides from the ultrasound-assisted A. bisporus hydrolysate according to Q values, iUmami-SCM, Umami_YYDS, and Tastepeptides_DM models, and molecular docking. Five peptides (AGKNTNGSQF, DEAVARGATF, REESDFQSSF, SEETTTGVHH, and WNNDAFQSSTN) were synthesized for sensory evaluation and kinetic analysis. The result showed that the umami thresholds of the five peptides were in the range of 0.21-0.40 mmol/L. Notably, REESDFQSSF, SEETTTGVHH, and WNNDAFQSSTN had low dissociation constant (KD) values and high affinity for the T1R1-VFT receptor. The enhancing effect of the three peptides with MSG or IMP was investigated by sensory evaluation, kinetic analysis, and molecular dynamics simulations. In stable complexes, ARG_277 in T1R1 played a major role in umami peptide binding to T1R1-VFT. These results provide a theoretical basis for future screening of umami peptides and improving the umami taste of food containing mushrooms.

Identification, screening and taste mechanisms analysis of two novel umami pentapeptides derived from the myosin heavy chain of Atlantic cod (Gadus morhua)

Umami peptides are new ingredients for the condiment and seasoning industries, with healthy and nutrition characteristics, some of which were identified from aquatic proteins. This study aims to further explore novel umami peptides from Atlantic cod (Gadus morhua) by combining in silico, nano-HPLC-MS/MS, sensory evaluation, and electronic tongue analysis. Two novel peptides, Leu-Val-Asp-Lys-Leu (LVDKL) and Glu-Ser-Lys-Ile-Leu (ESKIL), from the myosin heavy chain of Atlantic cod (Gadus morhua), were screened and confirmed to have strong umami tastes with the thresholds of 0.427 mM and 0.574 mM, respectively. The molecular docking was adopted to explore the interactions between the umami peptides and the umami taste receptor T1R1/T1R3, which showed that the umami peptides interacted with T1R1/T1R3 mainly by electrostatic interaction, hydrogen bond interaction, and hydrophobic interaction. Furthermore, the physicochemical properties of the peptides were investigated by in silico methods and cell viability experiments. This study will provide a better understanding of the umami taste in Atlantic cod and will promote the development of condiments and seasonings.

Flavor Characteristics of Umami Peptides from Wuding Chicken Revealed by Molecular Dynamics Simulation

Wuding chicken is famous for its delicious meat, and HLEEEIK, LDDALR, and ELY were jointly extracted from different processing stages of Wuding chicken. However, whether these peptides can be used as umami supplements is unclear. The sensory evaluation tests were used to study the taste characteristics. The secondary structure of the peptides and their interaction with T1R1/T1R3 were predicted by the circular dichroism spectrum and molecular dynamics simulation. The umami threshold was 0.03125 to 0.06250 mg/mL, all of which could increase umami, saltiness, sweetness, and mask bitterness. Compared with HLEEEIK, the frequency of umami active fragments and the improvement rate of the umami score of EEE increased by 133.35% and 40.09%, respectively. Peptides were dominated by umami taste according to sensory analysis, among which EE-3 (3.18) has the highest umami intensity followed by LR-4 (2.58), HK-7 (2.13), and EY-3 (1.82). The main secondary structure of umami peptides was β-folding, and Tyr74, Arg323, Arg272, and Gln35 were the key amino acid residues for binding of umami peptides to the receptor. This study further elucidated that the umami intensity of the peptides could be altered by changing the sequence composition of the peptides, which enhanced our understanding of the complex flavor properties of umami peptides.

Virtual screening and characteristics of novel umami peptides from porcine type I collagen

This study aimed to rapidly and precisely discover novel umami peptides from porcine type I collagen using virtual screening, sensory evaluation and molecular docking simulation. Porcine type I collagen was hydrolyzed in silico and six umami peptide candidates (CN, SM, CRD, GESMTDGF, MS, DGC) were shortlisted via umami taste, bioactivity, toxicity, allergenicity, solubility and stability predictions. The sensory evaluation confirmed that these peptides exhibited umami taste, with CRD, GESMTDGF and DGC displaying higher umami intensity and significant umami-enhancing effects in 0.35% sodium glutamate solution. Molecular docking predicted that Ser 276/384/385 of T1R1 and Asn68, Val277, Thr305, Ser306, Leu385 of T1R3 may also play critical roles in binding umami peptides. The umami taste of peptides may be perceived mainly through the formation of hydrogen bonds with the hydrophilic amino acids of T1R1/T1R3. This work provided a robust procedure and guidance to develop novel umami peptides from food byproducts.

Identification of the Bioavailable Peptidome of Chia Protein Hydrolysate and the In Silico Evaluation of Its Antioxidant and ACE Inhibitory Potential

The incorporation of novel, functional, and sustainable foods in human diets is increasing because of their beneficial effects and environmental-friendly nature. Chia (Salvia hispanica L.) has proved to be a suitable source of bioactive peptides via enzymatic hydrolysis. These peptides could be responsible for modulating several physiological processes if able to reach the target organ. The bioavailable peptides contained in a hydrolysate obtained with Alcalase, as functional foods, were identified using a transwell system with Caco-2 cell culture as the absorption model. Furthermore, 20 unique peptides with a molecular weight lower than 1000 Da and the higher statistical significance of the peptide-precursor spectrum match (-10 log P) were assessed by in silico tools to suggest which peptides could be those exerting the demonstrated bioactivity. From the characterized peptides, considering the molecular features and the results obtained, the peptides AGDAHWTY, VDAHPIKAM, PNYHPNPR, and ALPPGAVHW are anticipated to be contributing to the antioxidant and/or ACE inhibitor activity of the chia protein hydrolysates.

Peptidomics Screening and Molecular Docking with Umami Receptors T1R1/T1R3 of Novel Umami Peptides from Oyster (Crassostrea gigas) Hydrolysates

In this study, novel umami peptides were prepared from oyster (Crassostrea gigas) hydrolysates, and their umami mechanisms were investigated. Umami fractions G2 and G3 were isolated by gel filtration chromatography (GFC) and sensory evaluation. The umami scores of the G2 and G3 fractions were 7.8 ± 0.12 and 7.5 ± 0.18, respectively. 36 potential umami peptides with molecular weights below 1500 Da, E and D accounting for >30% of the peptides and iUmami-SCM > 588 were screened by peptidomics. Peptide source analysis revealed that myosin, paramyosin, and sarcoplasmic were the major precursor proteins for these peptides. The electronic tongue results demonstrated that the synthetic peptides DPNDPDMKY and NARIEELEEE possessed an umami characteristic, whereas SIEDVEESRNK and ISIEDVEESRNK possessed a saltiness characteristic. Additionally, molecular docking results indicated that the umami peptide (DPNDPDMKY, NARIEELEEE, SIEDVEESRNK, and ISIEDVEESRNK) binds to H145, S276, H388, T305, Y218, D216, and Q389 residues in the T1R3 taste receptor via a conventional hydrogen bond and a carbon-hydrogen bond. This research provides a new strategy for the screening of umami peptides.

Excavation, identification and structure-activity relationship of heat-stable umami peptides in the processing of Wuding chicken

Umami peptides from different stages of Wuding chicken processing were discovered, isolated, and purified using ultrafiltration membrane, gel filtration chromatography, and reversed-phase high-performance liquid chromatography, and the binding mechanism was explored. Twelve umami peptides were found by nano-scale liquid chromatography-tandem mass spectrometry, three of which (HLEEEIK, LDDALR, and ELY) existed throughout the processing step. The umami score and the frequency of active fragments of umami were highest for LEEEL, followed by EEF. The main active sites between umami peptide and receptor T1R1/T1R3 were Tyr262, Glu325, and Glu292, and hydrophobic interaction and hydrogen bonding were the main forces, and bitter amino acids were also important components of umami peptides. It was found for the first time that heat-stable umami peptides exist in Wuding chickens, which provides a basis for the identification and screening of umami peptides in local chickens, and also helps to study the structure-activity relationship of umami peptides.

Identification, Characterization, and Receptor Binding Mechanism of New Umami Peptides from Traditional Fermented Soybean Paste (Dajiang)

Dajiang, a traditional Chinese condiment, is made from fermented soybeans. It is highly popular among consumers as a result of its delicious umami flavor, which mainly originates from umami peptides. To examine the mechanism of umami taste in Dajiang, we selected Dajiang samples with strong umami taste and subjected them to purification and identification analysis using ethanol precipitation, gel chromatography, reversed-phase high-performance liquid chromatography, and ultraperformance liquid chromatography-tandem mass spectrometry. Subsequently, on the basis of toxicity and umami prediction analysis, we screened, synthesized, and characterized three novel bean umami peptides in Dajiang: TLGGPTTL, 758.4174 Da; GALEQILQ, 870.4811 Da; and HSISDLQ, 911.4713 Da. Their sensory threshold values were 0.25, 0.40, and 0.17 mmol/L, respectively. Furthermore, molecular docking results showed that hydrogen-bonding and hydrophobic interactions are important interaction forces in the binding of umami peptide to taste receptors. Ser147 and Glu148 of the T1R3 taste receptor are important amino acid residues for binding of the three umami peptides. This study uncovers the mechanism of umami-peptide-driven flavor in fermented soybean products.

Identification and Verification of Novel Umami Peptides Isolated from Hybrid Sturgeon Meat (Acipenser baerii × Acipenser schrenckii)

To explore the umami mechanism in sturgeon meat, five peptides (ERRY, VRGPR, LKYPLE, VKKVFK, and YVVFKD) were isolated and identified by ultrafiltration, gel filtration chromatography, and UPLC-QTOF-MS/MS. The omission test confirmed that the five umami peptides contributed to the umami taste of sturgeon meat. Also, the peptides had the double effective role of enhancing both umami and saltiness. The threshold of ERRY was only 0.031, which exceeded most umami peptides in the last 3 years. Molecular docking results showed that five peptides could easily bind to Gly167, Ser170, and Try218 residues in T1R3 through hydrogen bonds and electrostatic interactions. Furthermore, molecular dynamics simulations indicated that hydrogen bonds and hydrophobic interactions were the main intermolecular interaction forces. This study could contribute to revealing the umami taste mechanism of sturgeon meat and provide new insights for effective screening of short umami peptides.

Identification of Novel Umami Peptides in Termitornyces albuminosus (Berk) Heim Soup by In Silico Analyses Combined with Sensory Evaluation: Discovering Potential Mechanism of Umami Taste Formation with Molecular Perspective

In this study, 24 peptides were identified in Termitornyces albuminosus (Berk) Heim soup, 12 of which were predicted to possess an umami taste based on the BIOPEP-UWM or Umami-MRNN databases. Among these 12 peptides, four peptides (i.e., QNDF, QGGDF, EPVTLT, and EVNYDFGGK) exhibited the lowest affinity energy with the umami receptor type 1 member 1 (T1R1) subunit. Molecular docking and molecular dynamics simulation further confirmed the strong binding of these four umami peptides to the umami receptor T1R1/T1R3, with the EVNYDFGGK forming the most stable complex. After synthesizing the four peptides, their umami taste was validated through sensory and electronic tongue analyses with recognition thresholds ranging from 0.0938 to 0.3750 mmol/L. Notably, the EVNYDFGGK peptide displayed the strongest umami taste (recognition threshold, 0.0938 mmol/L). This study may contribute to the industrial development of T. albuminosus by providing a new understanding of the mechanism of its umami formation.

A Machine Learning Method to Identify Umami Peptide Sequences by Using Multiplicative LSTM Embedded Features

Umami peptides enhance the umami taste of food and have good food processing properties, nutritional value, and numerous potential applications. Wet testing for the identification of umami peptides is a time-consuming and expensive process. Here, we report the iUmami-DRLF that uses a logistic regression (LR) method solely based on the deep learning pre-trained neural network feature extraction method, unified representation (UniRep based on multiplicative LSTM), for feature extraction from the peptide sequences. The findings demonstrate that deep learning representation learning significantly enhanced the capability of models in identifying umami peptides and predictive precision solely based on peptide sequence information. The newly validated taste sequences were also used to test the iUmami-DRLF and other predictors, and the result indicates that the iUmami-DRLF has better robustness and accuracy and remains valid at higher probability thresholds. The iUmami-DRLF method can aid further studies on enhancing the umami flavor of food for satisfying the need for an umami-flavored diet.