Effects of continuous enzymolysis on the umami characteristics of Lentinula edodes and the flavor formation mechanism of umami peptides

Flavor effect, application status, and research trend of umami peptides based on microbial fermentation in food

Umami peptides are important non-volatile compounds produced by protein degradation, contributing to food umami flavor and enhancing product quality. Microbial fermentation promotes the production of taste peptides, including umami peptides, which act as key flavor substances and precursors. Microbial-derived umami peptides are cost-effective, easy to produce, and a major source of umami peptide production. Although microbial fermentation of umami peptides has been extensively studied in preparation, screening, and evaluation, a systematic review of microbial fermentation is still lacking. Therefore, this paper aims to address the following aspects: (1) umami peptide taste characteristics, influencing factors, and preparation methods; (2) microbial sources of umami peptides; (3) the current application status of microbial fermentation-derived umami peptides in various foods; and (4) future directions for microbial fermentation of umami peptides. Consequently, this literature review seeks to offer insights for advancing microbial fermentation in umami peptide production.

Optimization of enzymatic hydrolysate process of Volvariella volvacea and analysis of volatile flavor compounds in Maillard reaction

BACKGROUND

Edible fungi seasoning not only enhances umami flavor but also improves nutritional value in the production of traditional Chinese cuisine. Volvariella volvacea is a typical tropical and subtropical tasty edible fungus, with an annual production in China reaching 330, 000 tons, accounting for 80% of the global yield. Therefore, the high-value utilization of V. volvacea has become one of the current research hotspots. This study aimed to determine the optimal reaction conditions for the enzymatic hydrolysate and Maillard reaction (MR) products of V. volvacea and to identify the odor compounds in the enzymatic hydrolysate and MR products of V. volvacea to enhance the umami taste of V. volvacea.

RESULTS

The optimal conditions for enzymatic hydrolysate were a solid/liquid ratio of 1:10, pH 5.5, enzyme concentration of 4000 U g-1 (cellulase:Protamex™ = 1:1), a cellulase hydrolysis time of 90 min, followed by ProtamexTM hydrolysis for 120 min, resulting in optimal umami. An MR was performed to further release umami compounds in V. volvacea. The optimal conditions for the MR were determined to be 3% xylose, 5% cysteine, 110 °C, 80 min, and pH 6.0. Finally, odor compounds before and after the MR of V. volvacea were analyzed using two-dimensional gas chromatography-olfactometry-mass spectrometry. The results revealed that chicoric ketone (sweet) was the most abundant (125.78 ± 11.71 μg kg-1), followed by furfural (bread; 107.21 ± 2.83 μg kg-1) and 2-methylfuran (chocolate; 90.27 ± 2.66 μg kg-1).

CONCLUSION

This study provides more information for further studies on the umami compounds of V. volvacea and a theoretical basis for the development and utilization of V. volvacea. © 2025 Society of Chemical Industry.

Identification of Novel Umami Peptides from Low-Salt Dry-Cured Ham Skin and Revelation of the Umami Mechanism through Molecular Docking with T1R1/T1R3

Dry-cured ham is highly favored by consumers due to its unique flavor, which is attributed to its various umami peptides. Four novel umami peptides were isolated from the skin of low-salt dry-cured ham. Sensory evaluations and electronic tongue analysis demonstrated that these peptides exhibited umami thresholds of 0.125-0.5 mg/mL. Molecular docking with the T1R1/T1R3 receptor gave binding energies ranging from -8.6 to -7.638 kcal/mol, demonstrating that hydrogen bonds and van der Waals forces represent the main forces involved in the binding of these peptides to the umami receptor. Hydrogen bonding significantly enhance the binding stability, while the van der Waals forces optimize the binding conformation to promote conduction of the umami signal. These findings confirm the presence of novel umami peptides in the skin of low-salt dry-cured ham, thereby enriching the umami peptide database and providing a theoretical basis for the high-value utilization of byproducts in livestock product processing.

Identification, characterization and molecular docking study of umami peptides from Spanish mackerel head enzymatic hydrolysate and Maillard reaction products

Umami peptides were screened and identified from the enzymatic hydrolysate of Spanish mackerel head and its Maillard reaction products using ultrafiltration, gel chromatography, and LC-MS/MS (Liquid Chromatography-Tandem Mass Spectrometry). The umami properties of these peptides were subsequently evaluated and characterized using electronic tongue analysis and molecular docking. This study is the first to employ enzymatic hydrolysis combined with Maillard reaction for the preparation of umami peptides from Spanish mackerel head. Following this approach, a total of nine novel umami peptides were identified, including five from enzymatic hydrolysate (YDDKIY, ITPDEKGTTF, DAITTDDAGK, LEDGYPKEIQE, DAITPDEKGTTF) and four from Maillard reaction products (KDEGSDV, TPDEKGT, TEKAKGEP, FDAITPDEKGTTF). Sensory evaluation and electronic tongue analysis confirmed their distinct umami properties, with taste recognition thresholds ranging from 0.125 to 0.25 mg/mL. Molecular docking analysis revealed that these peptides interact with the T1R1/T1R3 umami receptor through hydrogen bonding and hydrophobic interactions, with key binding residues identified as Ser150, Ser256, and Glu128. This study provides a novel methodology for screening umami peptides from seafood by-products and lays the groundwork for their application as natural umami enhancers in the food industry.

A novel directed enzymolysis strategy for the preparation of umami peptides in Stropharia rugosoannulata and its mechanism of taste perception

This study aimed to explore the effect of directed enzymolysis on the umami characteristics of S. rugosoannulata, clarify the flavour formation mechanism of umami peptides. We expressed a new aminopeptidase (DNPEP) and obtained the umami peptides of S. rugosoannulata by alkaline protease and DNPEP. The optimal enzymolysis conditions were temperature 55 °C, solid-liquid ratio 1:20 (g/mL), alkaline protease enzymolysis (60 min, 0.5 %, pH 9.0), and DNPEP enzymolysis (80 min, 0.3 %, pH 8.0). The umami peptide components were separated by ultrafiltration and gel filtration chromatography. Six umami peptides (EEAKFN, KAELDLH, LADVEEDK, LKEAHDVA, AHLDYGDGK, and LGKSEDDVSK) were identified by LC-MS/MS and virtual screening, and the umami thresholds of the peptides were 0.15-1.09 mmol/L. Molecular simulations revealed that the amino acid residues Glu301, Ser217, Asp218, and Arg277 were crucial in the binding of the umami peptide to the T1R1/T1R3. Therefore, this study provides a theoretical basis for the development of mushroom condiments.

Identification and characterization of umami-ACE inhibitory peptides from traditional fermented soybean curds

Fermented soybean curds (FSC) are popular because of its umami taste. Its bioactivities are of interest. Peptides in FSC were identified using nano-HPLC-MS/MS, and 11 candidate peptides showing potential umami and ACE inhibitory activities were screened using various databases. Pharmacophore model analysis showed their high probability of ACE inhibition with fit values >2, which showed the peptides bound to umami receptors and ACE mainly through hydrogen bond, and electrostatic and hydrophobic interactions. Additionally, their docking and interaction energy were independent of the peptide length. Three high umami-ACE inhibitory peptides (VE, FEF, and WEEF) were synthesized. Their umami thresholds were WEEF (0.32 mM) < FEF (0.55 mM) < VE (1.10 mM), while their IC50 were WEEF (85 ± 2 μM) < FEF (170 ± 10 μM) < VE (205 ± 5 μM). NO and ET-1 production were dose-dependent with WEEF showing the best ACE inhibitory activity. The results allowed identification of effective umami agents and ACE inhibitory peptides from fermented soybean products. It could also be useful method for screening potential umami-ACE inhibitory peptides.

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.

Identification and taste characteristics of novel umami peptides from Yanjin black bone chicken hydrolysates and their binding mechanism with umami receptor

This study aimed to obtain umami peptides from Yanjin black bone chicken and to investigate the formation mechanism of umami taste. The umami peptides were purified from the enzymatic hydrolysate of chicken using ultrafiltration (UF), gel filtration chromatography (GFC), and reversed-phase high-performance liquid chromatography (RP-HPLC). Potential novel umami peptides were then identified by nano-scale liquid chromatography-tandem mass spectrometry (nano-HPLC-MS/MS). Based on the predictions of iUmami-SCM and BIOPEP-UWM databases, five umami peptides (EELK, EEEIK, EELMK, LEEEIK, DELDKYS) with high umami scores were synthesized. Sensory evaluation revealed that these umami peptides exhibited a threshold ranging from 0.12 mg mL-1 to 0.36 mg mL-1. Circular dichroism (CD) analysis indicated the presence of β-sheet structures in the umami peptides that could be associated with taste formation. In addition, molecular docking and molecular dynamics (MD) were employed to investigate the binding mechanisms between umami peptides and the umami receptor T1R1/T1R3. The findings reveal that Lys155, Arg255, and Gln250 of T1R1/T1R3 potentially play critical roles in umami peptide binding. Taken together, our results lay a foundation for researching flavor substances and for developing flavor products from Yanjin black bone chicken.

A review of taste-active compounds in meat: Identification, influencing factors, and taste transduction mechanism

Poultry and livestock meat are important parts of the human diet. As living standards have improved, food taste has become a major influence on consumer quality assessment and meat purchasing choices. There is increasing research interest in meat taste and meat taste-active compounds, which include free amino acids, flavor nucleotides, taste-active peptides, organic acids, soluble sugars, and inorganic ions. Taste component research is also an important part of sensory science. A deeper understanding of the meat taste perception mechanism and interactions among different taste compounds will promote the development of meat science and sensory evaluation. This article reviews the main taste compounds in meat, factors influencing their concentrations, and the identification and measurement of taste-active compounds, as well as summarizing the mechanisms of taste sensing and perception. Finally, the future of scientific taste component evaluation is discussed. This review provides a theoretical basis for research on meat taste and an important reference for the development of the meat industry.

Preparation of umami peptides from chicken breast by batch coupled enzymatic hydrolysis and membrane separation mode and the taste mechanism of identified umami peptides

Batch coupled enzymatic hydrolysis and membrane separation mode (BCEH-MSM) is efficient in preparing active peptides due to enzyme being more purposeful in hydrolysing macromolecular. Therefore, BCEH-MSM probably could be an alternative option to the traditional enzymatic hydrolysis and offline membrane separation mode (TEH-OMSM). This work aimed to explore the potential of BCEH-MSM in enhancing the enzymatic hydrolysis (EH) efficiency and the umami of the enzymatic hydrolysate. The EH efficiency was valuated based on product yields. Amino acid analyzer and HPLC were used to analyze tasting compounds. Electronic-tongue was used to determine umami intensity. The results showed that BCEH-MSM exhibited superior EH efficiency and higher umami intensity compared to TEH-OMSM. LC-MS/MS was used to identify peptides with higher umami intensity in the enzymatic hydrolysate. LGEETF, VNFDGEI, and QLSELLRAGSSPNL had umami profile verified by electronic-tongue. Molecular docking further showed that crucial amino acid residues involved in the binding to T1R1/T1R3 was His145.

Unraveling the flavor profiles of chicken meat: Classes, biosynthesis, influencing factors in flavor development, and sensory evaluation

Chicken is renowned as the most affordable meat option, prized by consumers worldwide for its unique flavor, and universally recognized for its essential savory flavor. Current research endeavors are increasingly dedicated to exploring the flavor profile of chicken meat. However, there is a noticeable gap in comprehensive reviews dedicated specifically to the flavor quality of chicken meat, although existing reviews cover meat flavor profiles of various animal species. This review aims to fill this gap by synthesizing knowledge from published literature to describe the compounds, chemistry reaction, influencing factors, and sensory evaluation associated with chicken meat flavor. The flavor compounds in chicken meat mainly included water-soluble low-molecular-weight substances and lipids, as well as volatile compounds such as aldehydes, ketones, alcohols, acids, esters, hydrocarbons, furans, nitrogen, and sulfur-containing compounds. The significant synthesis pathways of flavor components were Maillard reaction, Strecker degradation, lipid oxidation, lipid-Maillard interaction, and thiamine degradation. Preslaughter factors, including age, breed/strain, rearing management, muscle type, and sex of chicken, as well as postmortem conditions such as aging, cooking conditions, and low-temperature storage, were closely linked to flavor development and accounted for the significant differences observed in flavor components. Moreover, the sensory methods used to evaluate the chicken meat flavor were elaborated. This review contributes to a more comprehensive understanding of the flavor profile of chicken meat. It can serve as a guide for enhancing chicken meat flavor quality and provide a foundation for developing customized chicken products.

Exploring of multi-functional umami peptides from Stropharia rugosoannulata: Saltiness-enhancing effect and mechanism, antioxidant activity and potential target sites

Umami peptides enhance flavor and offer potential health benefits. We analyzed the taste-value profiles of five novel umami peptides from Stropharia rugosoannulata using E-tongue, exhibiting significant saltiness characteristics. While the peptides PHEMQ and SEPSHF exhibited higher saltiness, their mixture with salt did not enhance saltiness compared to individual peptides. Surprisingly, SGCVNEL, which was initially weak in saltiness, showed remarkably enhanced saltiness when mixed with salt, possibly due to have strong binding with receptors. Molecular docking elucidated the salt-forming mechanism of TMC4, highlighting the P2-domain and hydrogen bonds' role in the composite structure stability. Evaluation of the antioxidant activity evaluation demonstrated dose-dependent effects primarily through free radical scavenging via the single-electron transfer potential mechanism for SGCVNEL, EPLCNQ, and ESCAPQL. Docking experiments with antioxidant targets revealed varied binding stabilities, indicating diverse antioxidant effects of the peptides. These findings provide valuable insights into the exploration and application of versatile bioactive flavor peptides.

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.

Changes in flavor and biological activities of Lentinula edodes hydrolysates after Maillard reaction

This study aimed to elucidate how the Maillard reaction (MR) affects the flavor and bioactivities of Lentinula edodes hydrolysates (LEHs). Changes in flavor were investigated using non-targeted metabolomics techniques (GC-MS and LC-MS/MS) and sensory evaluation. Simultaneously, UV absorption, fluorescence, and FT-IR spectra were used to characterize the process of MR. We also evaluated the effects of MR on the antioxidant activity, hypoglycemic activity and antimicrobial activity of LEHs in vitro. The results revealed that MR produced many volatile aldehydes and ketones and decreased the content of most amino acids, sugars and flavonoids in the LEHs while increasing the content of l-theanine and succinic acid. MRPs had a strong caramel and like-meat flavor and an obvious improvement in umami, taste continuity, and total acceptability. Furthermore, MR improved the antioxidant and antimicrobial properties of LEHs. This research establishes a theoretical foundation for MR in the deep processing of edible mushrooms.

Comprehensive analysis of pigment alterations and associated flavor development in strip and needle green teas

Strip/needle green teas (SGT/NGT) processed using innovative technologies are in high demand; however, mechanisms behind their color and flavor have not been comprehensively studied. We aimed to reveal the dynamics of major pigmented components (carotenoids, lipids, flavonoids, and Maillard products) and their contributions to the flavor of green teas. The total content of flavonoids in SGT and NGT were 255 ± 4.51 and 201 ± 3.91 mg·g-1, respectively; these values are slightly lower than that in fresh leaves (FLs), resulting in a fresh and sweet aftertaste. In average, carotene content in SGT/NGT (24.8 μg·g-1) was higher than in FL (17.4 μg·g-1), whilst xanthophyll content (603 μg·g-1) decreased to one-half of that in FL (310 μg·g-1). Among the 218 primary metabolites, glutamine, glutamic acid, and arginine were found to accumulate and were dominate contributors for the umami and sweet taste. Notably, more than 96 volatiles were screened and revealed their correlations with carotenoids, lipids, and amino acids. Overall, the synergism between pigments and their non-enzymatic derivates' contribution to GT characterized flavor was illustrated.

Insights into major pigment accumulation and (non)enzymatic degradations and conjugations to characterized flavors during intelligent black tea processing

Intelligently processed black teas (BT) possess premium quality but there is a lack in comprehensive understanding of flavor formation mechanism. In this study, the accumulation of carotenoids, flavonoids, and Maillard products and (non)enzymatic degradations and conjugations to characterized flavors were comprehensively studied. Significant decrease was observed that flava-3-ols were heavily oxidised from > 240 mg·g-1 in fresh leaves (FL) to < 30 mg·g-1, while other 21 flavonoids decreased by < 30% in BT, accompanied by a sweet aftertaste. Carotenes and xanthophylls, significantly accumulated during withering compared to FL (from 641 ± 39.7 μg·g-1 to 728 ± 44.9 μg·g-1) but decreased in BT. Strong correlations were confirmed between the 218 primary metabolites, carotenoids, and flavonoids, and their contributions to BT sweet tastes were elucidated. Furthermore, 45 floral/sweet volatiles with VIP > 1 originating from carotenoids, lipids, and amino acids were screened. An integrated illustration of pigments thermal- and enzymatic-dominated contributions to BT flavour was comprehensively conducted.

Kokumi-Enhancing Mechanism of N-l-lactoyl-l-Met Elucidated by Sensory Experiments and Molecular Simulations

Recent research indicates that N-lactoyl amino acid derivatives have the potential as kokumi substances, with their kokumi profile closely linked to that of amino acids. This study aimed to explore the unexplored effects resulting from the introduction of lactate groups into l-Methional (l-Met), a prevalent flavor compound found in foods, such as tomatoes, known for its ability to activate the monosodium glutamate response. N-l-Lac-l-Met was enzymatically synthesized using food grade, and its taste profile and underlying mechanisms were investigated. The structure of N-l-Lac-l-Met was determined by high-performance liquid chromatography (HPLC)-mass spectrometry (MS)/MS. Sensory evaluation revealed the presence of astringency, kokumi, and bitterness of N-l-Lac-l-Met. In a stimulated broth, N-l-Lac-l-Met exhibited enhanced umami and kokumi taste perception compared to l-Met while demonstrating good stability within pH 5 to 9. A molecular simulation and quantum mechanics analysis indicated that the formation of an amide bond played a crucial role in the kokumi-enhancing effect of N-l-Lac-l-Met, specifically by increasing its affinity with umami receptors T1R1-T1R3 and a kokumi receptor CaSR. These findings established the relationship between amide bond formation and the kokumi-enhancing effect of N-l-Lac-l-Met, presenting its potential application as the kokumi substance in the food industry.