Isolation and identification of umami‐flavored peptides from Leccinum extremiorientale and their taste characteristic

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 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.

Identification, flavor characteristics and molecular docking of umami taste peptides of Xuanwei ham

To better understand the palatable properties of Xuanwei ham, the aqueous extract was isolated, analyzed and combin with sensory evaluation. Of umami-tasting activity and umami-enhancing impact, four new peptides (MDAIKKMQ, RKYEEVAR, YVGDEAQSKRG, and VNVDEVGGEALGR) were extracted and identified by ultrafiltration, gel separation, reverse performance liquid chromatography, and nano-LC-MS / MS. Sensory evaluation results showed that all of them had umami activity and enhanced umami taste, among which VNVDEVGGEALGR had the best effect. These peptides' umami taste thresholds ranged from 0.25 to 0.8 mg/mL. The MSG solution's umami taste threshold ranged from 0.125 to 0.5 mg/mL. Molecular docking results showed that the four umami peptides could be embedded into the binding pocket of the T1R3 cavity of the umami taste receptor T1R1/T1R3, wherein the binding sites Asp219, Asp150, and Thr179 may play crucial roles, and Glu222, Asp108, Glu217 and Glu148 play auxiliary roles. Hydrogen bonding and hydrophobic interactions were the most prominent interaction forces. This study helps to clarify the flavor characteristics of Xuanwei ham and could improve new processing technology.

Identification of umami peptides from Wuding chicken by Nano-HPLC-MS/MS and insights into the umami taste mechanisms

Wuding chicken is popular with consumers in China because of its umami taste. This study aimed to identify novel umami peptides from Wuding chicken and explore the taste mechanism of umami peptides. The molecular masses and amino acid compositions of peptides in Wuding chicken were identified by nano-scale liquid chromatography-tandem mass spectrometry (Nano-HPLC-MS/MS). The taste characteristics of the peptides synthesized by the solid-phase method were evaluated by sensory evaluation combined with electronic tongue technology. The secondary structure of the peptides was further analyzed by circular dichroism (CD), and the relationship between the structure and taste of the peptides was elucidated by molecular docking. The results showed that eight potential umami peptides were identified, among which FVT (FT-3), LDF (LF-3), and DLAGRDLTDYLMKIL (DL-15) had distinct umami tastes, and FT-3 had the highest umami intensity, followed by LF-3 and DL-15. The relative contents of β-sheets in the three umami peptides were 55.20%, 57.30%, and 47.70%, respectively, which were the key components of Wuding chicken umami peptides. In addition to LF-3 embedded in the cavity-binding domain of the TIR1, both FT-3 and DL-15 were embedded in the venus flytrap domain (VFTD) of the T1R3 to bind the umami receptor T1R1/T1R3. The main binding forces between the umami peptides and the umami receptor T1R1/T1R3 relied on hydrogen bonds and hydrophobic interactions, and the key amino acid residues of the combination of umami peptides and the umami receptor T1R1/T1R3 were Glu292, Asn235, and Tyr262.

Insights into the Flavor Differentiation between Two Wild Edible Boletus Species through Metabolomic and Transcriptomic Analyses

Despite the popularity of wild edible mushrooms due to their delectable flavor and nutritional value, the mechanisms involved in regulating and altering their taste remain underexplored. In this study, we analyzed the metabolome and transcriptome of Boletus brunneissimus (B. brunneissimus) and Leccinum extremiorientale (L. extremiorientale), two Boletus species collected from different environments. Using UHPLC-MS, we annotated 644 peaks and identified 47 differential metabolites via OPLS-DA analysis. Eight of these were related to flavor, including L-Aspartic acid, Glycine, D-Serine, L-Serine, L-Histidine, Tryptophan, L-Isoleucine, Isoleucine, and alpha-D-Glucose. These differential metabolites were mainly concentrated in amino acid metabolism pathways. Transcriptome analysis revealed differential genes between B. brunneissimus and L. extremiorientale, which were enriched in protein processing in the endoplasmic reticulum, as well as differential genes of the same Boletus species in different environments that were enriched in the ribosome pathway. The combination of metabolome and transcriptome analyses highlighted Glycine, L-Serine, and L-Aspartic acid as the key compounds responsible for the differences between the two Boletus species. Using the O2PLS model and Pearson's coefficient, we identified key genes that modulate the differences in metabolites between the two species. These results have significant implications for the molecular breeding of flavor in edible mushrooms.

Study on the relationship between structure and taste activity of the umami peptide of Stropharia rugosoannulata prepared by ultrasound

Through virtual screening, electronic tongue verification, and molecular docking technology, the structure-taste activity relationship of 47 kinds of umami peptides (octapeptide - undecapeptide) from Stropharia rugosoannulata prepared by simultaneous ultrasonic-assisted directional enzymatic hydrolysis was analyzed. The umami peptides of S.rugosoannulata can form hydrogen bond interaction and electrostatic interaction with umami receptors T1R1/T1R3. The amino acid residues at the peptides' N-terminal and C-terminal play a vital role in binding with the receptors to form a stable complex. D, E, and R are the primary amino acids in the peptides that easily bind to T1R1/T1R3. The basic amino acid in the peptides is more easily bound to T1R1, and the acidic amino acid is more easily bound to T1R3. The active amino acid sites of the receptors to which the peptides bind account for 42%-65% of the total active amino acid residues in the receptors. ASP147 and ASP219 are the critical amino acid residues for T1R1 to recognize the umami peptides, and ARG64, GLU45, and GLU48 are the critical amino acid residues for T1R3 to recognize the umami peptides. The increase in the variety and quantity of umami peptides is the main reason for improving the umami taste of the substrate prepared by synchronous ultrasound-assisted directional enzymatic hydrolysis. This study provides a theoretical basis for understanding simultaneous ultrasound-assisted directional enzymatic hydrolysis for preparing umami peptides from S.rugosoannulata, enhancing the flavor of umami, and the relationship between peptide structure and taste activity.

Preparation, pungency and bioactivity of gingerols from ginger (Zingiber officinale Roscoe): a review

Ginger has been widely used for different purposes, such as condiment, functional food, drugs, and cosmetics. Gingerols, the main pungent component in ginger, possess a variety of bioactivities. To fully understand the significance of gingerols in the food and pharmaceutical industry, this paper first recaps the composition and physiochemical properties of gingerols, and the major extraction and synthesis methods. Furthermore, the pungency and bioactivity of gingerols are reviewed. In addition, the food application of gingerols and future perspectives are discussed. Gingerols, characterized by a 3-methoxy-4-hydroxyphenyl moiety, are divided into gingerols, shogaols, paradols, zingerone, gingerdiones and gingerdiols. At present, gingerols are extracted by conventional, innovative, and integrated extraction methods, and synthesized by chemical, biological and in vitro cell synthesis methods. Gingerols can activate transient receptor potential vanilloid type 1 (TRPV1) and induce signal transduction, thereby exhibiting its pungent properties and bioactivity. By targeted mediation of various cell signaling pathways, gingerols display potential anticancer, antibacterial, blood glucose regulatory, hepato- and renal-protective, gastrointestinal regulatory, nerve regulatory, and cardiovascular protective effects. This review contributes to the application of gingerols as functional ingredients in the food and pharmaceutical industry.

Umami peptides screened based on peptidomics and virtual screening from Ruditapes philippinarum and Mactra veneriformis clams

The existing technology used for screening umami peptides is time-consuming and labor-intensive, making it difficult to meet the requirements of rapid screening of peptides. In this study, a high-throughput screening method for umami peptides was established based on peptidomics and virtual screening including the mass spectrometry, iUmami-SCM, PeptideRanker, and T1R1/T1R3 receptor. Subsequently, they were characterized and validated using sensory evaluation and electronic tongue. Results showed that 18 potential umami peptides were screened from two clams. Among them, 16 peptides had umami characteristics with thresholds range 0.123-1.481 mmol/L, and the accuracy of the screening method was about 88.9%. Additionally, active sites such as Tyr143, Gly144, Ser146, Ala145, His121, Ser123, and Glu277 may play a critical role in flavor presentation by molecular docking with T1R1/T1R3. The paper could provide a fast and reliable method for screening umami peptides as well as lay the foundation for novel strategies for evaluating umami taste.

Research progress in the screening and evaluation of umami peptides

Umami is an important element affecting food taste, and the development of umami peptides is a topic of interest in food-flavoring research. The existing technology used for traditional screening of umami peptides is time-consuming and labor-intensive, making it difficult to meet the requirements of high-throughput screening, which limits the rapid development of umami peptides. The difficulty in performing a standard measurement of umami intensity is another problem that restricts the development of umami peptides. The existing methods are not sensitive and specific, making it difficult to achieve a standard evaluation of umami taste. This review summarizes the umami receptors and umami peptides, focusing on the problems restricting the development of umami peptides, high-throughput screening, and establishment of evaluation standards. The rapid screening of umami peptides was realized based on molecular docking technology and a machine learning method, and the standard evaluation of umami could be realized with a bionic taste sensor. The progress of rapid screening and evaluation methods significantly promotes the study of umami peptides and increases its application in the seasoning industry.