Search

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. • Peptidomics analysis of six yeast proteins was conducted using nano-LC-MS/MS. • Seven of the nine virtually screened peptides exhibited a confirmed umami taste. • AGVEDVY, LFEQHPEYRK, AFDVQ, GPTVEEVD, and NVVAGSDLR had umami-enhancing effects. • Peptide residues H, R, Y, D, Q, T, S, E are mainly bound to receptors via H-bonds. • Residues H, S, D, R, Y in T1R1/3 are particularly vital for umami taste perception. [ABSTRACT FROM AUTHOR]

Seasonings such as naturally fermented soy sauce without added monosodium glutamate (MSG), are currently a growth market in China. However, fraudulent and mislabeled zero-added MSG soy sauce may cause a risk of excessive MSG intake, increasing food safety issues for consumers. This study investigates stable carbon and nitrogen isotopes and 16 amino acids in typical Chinese in-market soy sauces and uses a similarity method to establish criteria to authenticate MSG addition claims. Results reveal most zero-added MSG soy sauces had lower δ 13C values (−25.2 ‰ to −17.7 ‰) and glutamic acid concentrations (8.97 mg mL−1 to 34.76 mg mL−1), and higher δ 15N values (−0.27 ‰ +0.95 ‰) and other amino acid concentrations than added-MSG labeled samples. A combined approach, using isotopes, amino acids, similarity coefficients and uncertainty values, was evaluated to rapidly and accurately identify zero-added MSG soy sauces from MSG containing counterparts. [Display omitted] • Isotopes and amino acids profiles were characterized for in-market soy sauces. • Strong correlations were found between isotopes and amino acids. • A new approach is proposed using similarity analysis to classify soy sauce. • A decision tree is established to identify zero-added MSG soy sauce. [ABSTRACT FROM AUTHOR]

• Virtual strategies were integrated for high-throughput screening of umami peptides. • Six novel umami peptides CN, SM, CRD, GESMTDGF, MS and DGC were identified. • CRD, GESMTDGF, DGC had higher umami intensity and obvious umami-enhancing effects. • Umami-tasting mechanism of peptides was partly revealed by docking with T1R1/T1R3. • H-bonds formed by hydrophilic AAs of T1R1/T1R3 play key roles in umami perception. 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. [ABSTRACT FROM AUTHOR]

• γ-Glu-AA-AAs were firstly synthesized with pea protein hydrolysate as substrates. • γ-Glu-AA-AAs exhibited taste-enhancing properties on umami, salty, and kokumi. • γ-Glu-AA-AAs interacted with CaSR and T1R3-MSG receptor. • Ser147, Ala168 and Ser170 were the key residues between the γ-Glu-AA-AAs and CaSR. Pea (Pisum sativum L.) protein hydrolysate (PPH) has a bitter taste, which has limited its use in food industry. γ-Glutamylation is used to debitter PPH. Results showed that the bitterness of PPH was decreased significantly due to the formation of γ-glutamyl peptides, including 16 γ-[Glu] (n=1/2) -amino acids (AAs) and 8 newly discovered γ-glutamyl tripeptides (γ-Glu-Asn-Phe, γ-Glu-Leu-Val, γ-Glu-Leu-Tyr, γ-Glu-Gly-Leu, γ-Glu-Gly-Phe, γ-Glu-Gly-Tyr, γ-Glu-Val-Val, and γ-Glu-Gln-Tyr). Their total production concentrations were 27.25 μmol/L and 77.76 μmol/L, respectively. The γ-Glu-AA-AAs presented an umami-enhancing, salty-enhancing, and kokumi taste when their concentration reached 1.67 ± 0.20 ∼ 2.07 ± 0.20, 1.65 ± 0.25 ∼ 2.29 ± 0.45 and 0.68 ± 0.19 ∼ 1.03 ± 0.22 mmol/L, respectively. The γ-Glu-AA-AAs exhibited a kokumi taste by entering the Venus flytrap (VFT) of the calcium-sensing receptor and interacting with Ser147, Ala168, and Ser170. γ-Glu-AA-AAs can enhance the umaminess of Monosodium Glutamate (MSG) as they can enter the binding pocket of the taste receptor type 1 subunit 3 (T1R3)-MSG complex. [ABSTRACT FROM AUTHOR]

• Sensory-guided fractionation revealed umami compounds in pea protein isolate. • Monosodium glutamate (MSG) was found at subthreshold concentrations. • Ribonucleotides were identified as umami enhancing compounds with MSG. • Ribonucleotides reported synergistic umami enhancing activity. The umami taste of pea protein ingredients can be desirable or undesirable based on the food application. The compounds contributing to the umami perception of pea protein isolate (PPI) were investigated. Sensory-guided prep-liquid chromatography fractionation of a 10% aqueous PPI solution revealed one well-known compound, monosodium glutamate (MSG), however, it was reported at a subthreshold concentration. Two umami enhancing compounds 5′-adenosine monophosphate (AMP) and 5′-uridine monophosphate (UMP) were subsequently identified after the LC fractions were re-evaluated with MSG. Sensory recombination studies, utilizing the aqueous PPI solution as the base, confirmed AMP and UMP were umami enhancers of MSG and contributed approximately 81% of the perceived umami intensity. However UMP was only reported to enhance umami perception in combination with AMP (not individually) indicating synergistic interactions were observed between the two enhancer compounds. Therefore the presence of all three compounds are important for umami perception and provide an improved basis to tailor the flavor profile in PPI products. [ABSTRACT FROM AUTHOR]

Highlights • Identification of six novel umami and umami-enhancing peptides from PPIH. • RGENESEEEGAIVT was the first discovered umami and umami-enhancing tetradecapeptide. • Peptides could enhance the overall taste of chicken soup and soy sauce. • E-tongue has the potential to distinguish taste attributes of peptide solutions. Abstract Six novel peptides were separated from peanut protein isolate hydrolysate (PPIH) using ethanol precipitation and gel chromatography, and identified as DQR, NNP, EGF, EDG, TESSSE and RGENESEEEGAIVT by UPLC–ESI–QTOF–MS/MS. On the basis of sensory results, all peptides were perceived umami with threshold values from 0.39 to 1.11 mM and had umami-enhancing abilities simultaneously with threshold values from 0.33 to 0.82 mM. RGENESEEEGAIVT was the first discovered tetradecapeptide with umami and umami-enhancing ability. The dose–response test revealed that umami-enhancing activities of identified peptides were different: TESSSE and RGENESEEEGAIVT imparted better umami intensity when equimolar monosodium glutamate (MSG) was added into 0.5 g/L MSG solution. Taste profile analyses of complex mixtures with/without synthetic peptides were determined by both electronic tongue and human panellists, suggesting that umami peptides influence multiple tastes and electronic tongue has the potential to replace sensory test to distinguish taste attributes of foods rich in peptides. [ABSTRACT FROM AUTHOR]

Highlights • An electrochemical immunosensor was constructed for detecting MSG in foodstuffs. • Au@MoS 2 /Ch nanocomposite was evaluated for enhancing the sensor performance. • Real food sample analysis was carried out to obtain the sensor's functionality. • The proposed technique was proved to be practical, selective and sensitive. Abstract We report an amperometric immunosensor for the detection of monosodium glutamate (MSG) using a glassy carbon electrode modified with gold nanoparticle decorated on a molybdenum disulfide/chitosan (Au@MoS 2 /Ch) nanocomposite. In the present detection technique, Au@MoS 2 /Ch was used as a conductive matrix and anti-glutamate antibody was immobilized on to its surface via carbodiimide coupling method. Chemical and morphological attributes of the various components of the immunosensor were confirmed by UV– vis spectroscopy, SEM, TEM and XRD analysis. Electrochemical characterizations were carried out by CV, DPV and EIS. Overall results showed the effective fabrication of highly conductive Au@MoS 2 /Ch nanocomposite for sensitive electrochemical detection of MSG. A linear relationship was perceived between the change in current and concentration of MSG. The relationship was found to be consistent in the detection range of 0.05–200 µM. Statistical validation of the assay showed limit of detection and limit of quantification values as 0.03 and 0.1 µM, respectively (R2 = 0.99). [ABSTRACT FROM AUTHOR]

Highlights • A novel bivariate model for the molecular docking and kinetic simulation with T1R1/T1R3 was created. • The addition of MSG enlarged the size of the binding cavity of T1R3. • The addition of MSG caused small peptides, such as bi- or tri-peptides, to bind with T1R3. • The number of residues increased which play critical roles in hydrogen bonds. Abstract In order to investigate the synergistic effect between umami peptides, monosodium glutamate (MSG) and the taste receptor T1R1/T1R3, a novel bivariate model was created based on our previous work. The results showed three specific changes upon the addition of MSG between umami peptides and T1R1/T1R3, in terms of energy and conformation. First, the addition of MSG enlarged the size of the binding cavity of T1R3 from 534.125 A3 to 1135.75 A3. Second, the addition of MSG caused small peptides to bind with T1R3, with the lowest docking energy and docking interaction energy, −77.2295 and −60.7146 kcal/mol respectively. Third, five binding residues ,including Glu-429, Gln-302, Gly-304, Try-107 and His-364, increased which play critical roles in hydrogen bonding. They are consistent with the results of electronic tongue and facilitate better understanding of the synergism. Furthermore, novel umami and umami-enhanced compounds could be discovered, based on the use of the novel bivariate model. [ABSTRACT FROM AUTHOR]

• Electrochemical impedimetric biosensor for umami substance detection was developed. • Electrochemical impedance spectroscopy enhanced T1R1 biosensor performance. • T1R1 biosensor had low detection limits for monosodium glutamate and inosine-5′-monophosphate. • T1R1 biosensor had wide linear ranges for monosodium glutamate and inosine-5′-monophosphate. Umami substances can provide a palatable flavour for food. In this study, an electrochemical impedimetric biosensor was developed for detecting umami substances. This biosensor was fabricated by immobilising T1R1 onto AuNPs/reduced graphene oxide/chitosan which was in advance electro-deposited onto a glassy carbon electrode. The evaluation by the electrochemical impedance spectrum method showed that the T1R1 biosensor performed well with low detection limits and wide linear ranges. Under the optimised incubation time (60 s), the electrochemical response was linearly related to the concentrations of the detected targets monosodium glutamate and inosine-5′-monophosphate within their respective linear range of 10-14 to 10-9 M and 10-16 to 10-13 M. The low detection limit of monosodium glutamate and inosine-5′-monophosphate was 10−15 M and 10−16 M, respectively. Moreover, the T1R1 biosensor exhibited high specificity to umami substances even in the real food sample. The developed biosensor still retained 89.24% signal intensity after 6-day storage, exhibiting a desirable storability. [ABSTRACT FROM AUTHOR]

Oenococcus oeni ( O. oeni ) induces malolactic fermentation to improve wine quality. However, the molecular basis of mechanisms involved in its freeze-drying resistance remains unclear. In this work, O. oeni SD-2a without freeze-drying (No-FD), with freeze-drying (FD) and freeze-drying with monosodium glutamate (MSG) (FD-MSG) were investigated. Flow cytometry results showed severe cell damage in FD cells and less membrane transmissibility in FD-MSG cells. Meanwhile, extracellular polymeric substances (EPS) were detected in FD and FD-MSG cells by scanning electron microscopy. Bioinformatic analysis revealed that varying proteins were involved in carbon, lipid and nucleic acids metabolism, stress response, oxidoreductase activity and signal sensing. Among the identified proteins, the highlighted proteins were those involved in polysaccharides production and signal sensing for freeze-drying resistance and cyclopropane fatty acid metabolism for MSG addition. [ABSTRACT FROM AUTHOR]

An effective and simultaneous liquid chromatography-tandem mass spectrometry (LC–MS/MS) method was used with the aim of quantifying monosodium glutamate (MSG) in foodstuffs, such as chips, taste cubes, sauces and soups. The results were linear ( R 2  = 1), with very low LOD and LOQ values, 1.0 µg/kg, 5.0 µg/kg, respectively. Excellent repeatability and reproducibility were also achieved. This highly sensitive and robust LC–MS/MS technique was applied successfully for the detection and quantification of MSG in a wide variety of foodstuffs. MSG contents ranged from 0.01 g/100 g to 15.39 g/100 g in food samples. Importantly, determination of free glutamic acid in the daily diet could also prevent various side effects associated with consumption of excess free glutamic acid. [ABSTRACT FROM AUTHOR]

• Metabolite variation in two species of chaya leaves was described. • Young chaya leaves exhibited high umami taste intensity. • l -glutamic acid and 5′-adenosine monophosphate accumulated in young leaves. • Quinic acid, trigonelline, and other small peptides are novel umami compounds. Chaya (Cnidoscolus chayamansa and C. aconitifolius) is a fast-growing medicinal plant, and its leaves exhibit a strong umami taste. Here metabolite variation and umami-related compounds in the leaves of two chaya species were determined using a multiplatform untargeted-metabolomics approach, electronic tongue, and in silico screening. Metabolite profiles varied between the leaves of the two species and among leaf maturation stages. Young leaves exhibited the highest umami taste intensity, followed by mature and old leaves. Partial least square regression and computational molecular docking analyses revealed five potent umami substances (quinic acid, trigonelline, alanyl–tyrosine, leucyl–glycyl–proline, and leucyl–aspartyl–glutamine) and three known umami compounds (l -glutamic acid, pyroglutamic acid, and 5′-adenosine monophosphate). The five substances were validated as novel umami compounds using electronic tongue assay; leucyl–glycyl–proline exhibited synergism with monosodium glutamate, thereby enhancing the umami taste. Thus, substances contributing to the taste of chaya leaves were successfully identified. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the taste characteristics of doenjang water extract (DWE) for component compounds that contribute to its taste. A 1% DWE solution elicited the highest umami taste ratings in a taste profile test. A 3% solution of DWE was used as substitute for 9.4% of monosodium glutamate in a taste soup base, and it masked the bitter taste of hydrolysed animal protein when mixed in solution. DWE was fractionated, based on molecular weights, and fraction IV (F-IV; 1000>MW⩾500) had the highest peptide contents and elicited the strongest umami taste. The acidic peptide fraction of F-IV elicited the strongest umami taste. The major bound-type amino acids in DWE, F-IV and the acidic peptide fraction were Glu and Asp. These data show that the umami taste characteristics were a result of the low molecular weight acidic peptides naturally produced during the fermentation of soybeans. [Copyright &y& Elsevier]

Abstract: The chemical composition (dry matter, crude protein, crude fat, total carbohydrates, and ash) and non-volatile components content (soluble sugars, free amino acids, and 5′-nucleotides) of 10 popular Croatian wild edible mushroom species (Agaricus campestris, Boletus edulis, Calocybe gambosa, Cantharellus cibarius, Craterellus cornucopioides, Entoloma clypeatum, Flammulina velutipes, Macroleptiota procera, Morchella elata, and Pleurotus ostreatus) were determined. All investigated mushrooms were found to be good sources of proteins and total carbohydrates, with contents varying in the ranges of 27.95–38.89, and 42.62–66.78g/100g, respectively. In addition, the fat contents were very low 1.34–6.45g/100g. B. edulis (19.87mg/g) showed the highest concentration of essential amino acids and M. elata (14.25mg/g) the lowest concentration. Monosodium glutamate-like components and total flavour 5′-nucleotides were the highest in C. cornucopioides (45.85 and 13.88mg/g, respectively), and lowest in F. velutipes (7.63 and 1.05mg/g, respectively). Equivalent umami concentration values in 10 Croatian wild edible mushrooms ranged from 73.78 to 1186.45g MSG/100g dry weight, and overall, all these mushrooms possessed highly umami taste. [Copyright &y& Elsevier]

Abstract: GABA-producing lactic acid bacteria were isolated from kimchi and salt-fermented Jot-gal, which are traditional Korean fermented foods. The strain, BJ-20, isolated from salt-fermented Jot-gal (cod gut), possessed the highest GABA-producing ability in MRS broth with 1% monosodium glutamate (MSG), as determined by thin layer chromatography. The BJ-20 strain was identified as Lactobacillus brevis and designated as L. brevis BJ20. A sea tangle solution was fermented over 5days to produce GABA using L. brevis BJ20. During fermentation, the GABA concentration dramatically increased, while the glutamic acid concentration decreased. This result indicates that the glutamic acid was converted to GABA by L. brevis BJ20 in the fermented sea tangle solution. Furthermore, the fermented solution exhibited strong antioxidant activities, such as DPPH scavenging, superoxide scavenging, and xanthine oxidase inhibition, which were higher than those of BHA as a positive control. [Copyright &y& Elsevier]

• Perceived umami intensity (PUI) is quantified in foods from seven categories by 2-AFC method. • PUI varied in umami component contents, food types and structures. • EUC is available in quantifying PUI of meat, dairy, vegetable and mushroom products. • Prediction models for PUI and EUC are established with data from E-tongue by BPNN. Umami intensity promotes food flavor blending and food choice, while a universal quantification procedure is still lacking. To evaluate perceived umami intensity (PUI) in seven categories of foods, modified two-alternative forced choice (2-AFC) method with monosodium glutamate as reference was applied. Meanwhile, we explored whether equivalent umami concentration (EUC) by chemical analysis and electronic tongue (E-tongue) are applicable in PUI quantification. The results indicated that EUC was appropriate in quantifying PUI of samples from meat, dairy, vegetable and mushroom groups (r = 1.00, p < 0.05). Moreover, models with a good prediction capacity for PUI and EUC (R 2 > 0.99) were established in separated food categories by back propagation neural networks, where E-tongue data were set as input. This study explored the effectiveness of the three methods in evaluating the PUIs of various foods, which provides multiple choices for the food industry. [ABSTRACT FROM AUTHOR]

Abstract: Spectrophotometric data followed by a suitable treatment of chemometric analysis were used for the simultaneous determination of monosodium glutamate (MSG), guanosine 5′-monophosphate (GMP) and inosine 5′-monophosphate (IMP) in stock cube samples, without any previous extraction step. By this way, the overlapping of the absorption spectra was resolved using a PLS-1 model. The concentration for experimental calibration matrix were varied between 5.03–34.2μgmL−1 for IMP and GMP, and 448–1399μg mL−1 for MSG. The relative errors of prediction (REPCV %) were 1.8, 2.8 and 3.1 for IMP, GMP and MSG, respectively. To verify the accuracy of the proposed method a recovery study on real samples was carried out with satisfactory results (92–110%). [Copyright &y& Elsevier]

Abstract: A survey on free glutamic acid (Glu) content in a variety of foods (broths, soups, sauces and salad dressings), with and without added monosodium glutamate (MSG), was carried out. A simple procedure, involving a dilution step for liquid samples or homogenization with 0.1N HCl for solid and slurry samples, followed by derivatization with o-phthaldialdehyde, HPLC separation on C18 column and spectrofluorometric detection, was employed to quantify Glu, as well as a number of other free amino acids and biogenic amines. Broths and soups with added MSG had Glu contents of 92.7–341mg/100g. The highest amounts of Glu in foods with no added MSG were found in products containing hydrolyzed proteins (up to 129mg/100g). None of the products ready for consumption exceeded the limit of 10g/kg of food, established by the European Directive, 95/2/CE [European Parliament and Council Directive (1995). No. 95/2/EC of 20 February 1995 on food additives other than colours and sweeteners. Official Journal, L061, 1–40]. Relatively high amounts of biogenic amines were found in marmite (77.3mg/100g of putrescine and 32.2mg/100g of tyramine) and soy sauce while broths and soups showed generally low amounts of biogenic amines, putrescine being the most represented. [Copyright &y& Elsevier]

Abstract: Three species of canned mushrooms are available in Taiwan, including Agaricus bisporus, Volvariella volvacea and Flammulina velutipes. The non-volatile taste components of fruit bodies and broth in cans were studied. Mushroom cans of V. volvacea and F. velutipes had similar weights whereas the cans of A. bisporus were lighter. Contents of soluble sugars and polyols were in the range of 22.9–30.9 and 5.62–14.2 mg g−1 for fruit bodies and broth, respectively. Contents of total free amino acids were in the descending order of F. velutipes (247 and 146 μg g−1)> A. bisporus (42.8 and 33.3 μg g−1)> V. volvacea (27.2 and 12.4 μg g−1) for fruit bodies and broth, respectively. Three mushrooms were considerably different in their profiles of free amino acids. γ-Aminobutyric acid was found in the canned mushrooms. As compared with other taste components, contents of monosodium glutamate-like components were relatively lower. Contents of flavour 5′-nucleotides were in the range 14.8–36.5 μg g−1. Equivalent umami concentration (EUC) values were in the range of 0.10–13.2 mg MSG/100 g and in the descending order of F. velutipes > A. bisporus > V. volvacea. However, EUC values were low and insignificant in canned mushrooms. [Copyright &y& Elsevier]

• Alkali could dissolve flocculated polymers increasing 21 % soluble MSGB. • Ultrasound mainly released intercellular components increasing 18% MSGB. • Papain and lysozyme had similar effects on cell wall degradation. • Combined treatment led to 78% soluble MSGB yielding 6.6 × 109 CFU mL-1 B. subtilis. • The key to improve B. subtilis production was the release of carbohydrate. Due to the hindrance of flocculated polymers and bacterial cell wall, the production of Bacillus subtilis using monosodium glutamate byproduct (MSGB) was low. With the assistance of scanning electron microscope images, effects of alkali, lysozyme, papain, ultrasound, and their combinations on MSGB were evaluated using the results of soluble protein, carbohydrate, monosaccharides and peptidoglycans. Alkali could dissolve flocculated polymers increasing 21% soluble MSGB, and thus enhanced the subsequent treatments (ultrasound, lysozyme, or papain) to increase 14–17% soluble MSGB. As ultrasound mainly released intercellular components (mannose, and glucose) while lysozyme or papain mainly released cell wall components (peptidoglycans), the combination of alkali, ultrasound, and enzymes led to a highest soluble MSGB (78%), yielding a maximal B. subtilis production of 6.6 × 109 colony-forming units mL−1. This yield was about 33 times that of using untreated MSGB, and the key to improve B. subtilis production was the release of carbohydrate. [ABSTRACT FROM AUTHOR]

• The typical kokumi-active γ-glutamyl peptides exhibit the umami-enhancing effect. • These γ-glutamyl peptides have certain affinity with T1R3 in the presence of MSG. • The Glu-301, Ala-302, Thr-305 and Ser-306 play critical roles in the ligand-T1R3-MSG interaction. • γ-E-γ-EV might exhibit the best umami-enhancing effect. The umami-enhancing effect of typical kokumi-active γ-glutamyl peptides was verified by sensory evaluation. To investigate the umami-enhancing molecular mechanism of the peptide on monosodium glutamate (MSG) taste, a novel hypothetical receptor, taste type 1 receptor 3 (T1R3)-MSG complex, was constructed. These peptides demonstrated strong interactions with T1R3-MSG. Moreover, four amino acid residues, Glu-301, Ala-302, Thr-305, and Ser-306, were critical in ligand-receptor interactions. In detail, γ-Glu-γ-Glu-Val (γ-E-γ-EV) readily interacts with T1R3 through hydrogen bonds and hydrophobic interactions. While γ-E-γ-EV did not bind to MSG, γ-Glu-Val (γ-EV) and γ-Glu-Leu (γ-EL) showed high binding affinity to MSG and interacted with T1R3 through hydrophobic bonds suggesting that the interactions between dipeptides and T1R3-MSG were weaker than tripeptides. These results demonstrated that kokumi-active γ-glutamyl peptides could enhance the umami taste of MSG, and exhibit synergistic effects in activating T1R3. This study provides a theoretical reference for interactions between the novel umami-enhancing substances and umami receptor. [ABSTRACT FROM AUTHOR]

• Thirty taste-associated odorants were identified from soy sauce by GC/O-AT. • Four saltiness-enhancing and six umami-enhancing odorants were detected. • 3-(Methylthio)propanal was the most effective odorant in enhancing salty and umami. • The umami-associated odorant 1-octen-3-ol could enhance saltiness significantly. Odor-taste interaction has become a popular salt reduction method. In this study, the odorants associated with saltiness in soy sauce were selected by gas chromatography/olfactometry-associated taste (GC/O-AT), and their ability to induce saltiness/umami enhancement was verified by sensory evaluation. A total of 30 taste-associated odorants were perceived, including 5 saltiness-associated and 2 umami-associated odorants. Among them, 3-(methylthio)propanal, 1-octen-3-ol, 3-(methylthio)-1-propanol, and 2,5-dimethylpyrazine could significantly enhance saltiness of 0.3% NaCl solution (p < 0.05). Furthermore, 3-(methylthio)propanal, maltol, 2,5-dimethyl-4-hydroxy-3(2 H)-furanone (HDMF), dimethyl trisulfide, 3-(methylthio)-1-propanol and 1-octen-3-ol could also enhance the umami taste in 0.3% monosodium glutamate solution. Compared with zero or strong-salt-content (0.8%) solution, the saltiness of weak-salt-content (0.3%) was enhanced significantly by adding the odorant. These results suggest that salty food is an efficient source for selecting saltiness-enhancing odorants, which could be used to compensate NaCl reduction in food. [ABSTRACT FROM AUTHOR]

• Disodium succinate (WSA) contributes to umami taste. • WSA exhibits the strongest relative umami taste at the condition of 25 °C, 0.1% Na+ addition, and pH 7.5. • WSA shows good stability after heat treatment. Disodium succinate (WSA) contributes to umami taste in seafoods and it is abundantly found in scallops. However, the actual application of WSA in foods is limited due to a lack of understanding of its taste characteristics and stability. In this study, two-alternative forced choice method was used to determine the relative umami intensity of WSA compared to monosodium glutamate, as well as the relative umami intensity under different conditions (pH and temperature). WSA concentration–taste intensity curve was established, which fitted well with a logarithmic-linear regression (R 2 = 0.96). WSA exhibited the strongest umami intensity at 25 °C, 0.1% Na+ addition, and pH 7.5. It also had a good thermal stability, which met the needs of high temperature heating during food processing. In conclusion, this research provided useful information on umami characteristics of WSA and the results widen the application of WSA in the food industry. [ABSTRACT FROM AUTHOR]