Synergistic Effect of Kokumi-Active γ-Glutamyl Peptides and l-Glutamate on Enhancing Umami Sensation and Stimulating Cholecystokinin Secretion via T1R1/T1R3 Activation in STC-1 Cells

Flavor and structure characteristics of egg white peptides based on γ-glutamylation modification: A promising flavor enhancement strategy

The widespread use of egg white peptides (EWP) in healthy foods is limited by undesirable flavors. In this study, transglutaminase (TG) was used to catalyze the γ-glutamylation reaction between glutamine (Gln) and EWP, modifying the structure and flavor of EWP. The interaction of Gln and EWP altered the primary structure and spatial conformation of EWP, thus increasing the solubility. γ-glutamylation reduced the bitterness and increased umami of EWP by consuming hydrophobic bitter amino acids and generating umami peptides. Twenty-one synthesized γ-glutamyl peptides were identified in G-EWP after γ-glutamylation, which could enhance the sweetness, saltiness, umami, and kokumi taste of basic substances. All of these peptides could enter the Venus flytrap (VFT) of calcium-sensing receptor (CaSR), which might be the mechanism of G-EWP with enhanced kokumi taste. Overall, this research provided the theoretical basis for flavor improvement of EWP.

TastePeptides-Meta: A One-Stop Platform for Taste Peptides and Their Structural Derivatives, Including Taste Properties, Interactions, and Prediction Models

Taste peptides have nutritional and sensory properties, and their structural derivatives show unique taste modulation effects. The increasing number of taste peptide candidates requires a fast and accurate screening methodology using advanced detection tools. Notably, existing platforms lack integrated bioinformatics solutions to provide accurate retrieval and prediction capabilities. In response to this need, TastePeptides-Meta is proposed, comprising 2,926 peptides entries, 975 peptide structural derivatives, and 954 synergistic (enhancing) data from 282, 109, and 103 peer-reviewed studies, respectively. It was equipped with corresponding machine learning-driven prediction modules and domain-specific analytical toolkits. As an online interactive platform, TastePeptides-Meta provides multiple interfaces that allow searching, downloading and predicting taste peptides. We believe that the public availability of TastePeptides-Meta and its implementation of standardized data schemas will accelerate mechanistic investigations in the field of taste peptides and the development of data-driven, interpretable models for predicting and exploring taste mechanisms. The TastePeptides-Meta platform can be accessed online at http://www.tastepeptides-meta.com/.

Identification of umami peptides and mechanism of the interaction with umami receptors T1R1/T1R3 in pigeon meat

OBJECTIVE

Pigeon meat offer an ideal source for extracting fresh flavor peptides. These peptides not only enhance the taste of food but also have potential health benefits, including providing low-sugar, low-sodium, and low-calorie options for individuals with conditions like diabetes, hypertension, and obesity. Therefore, further research into the pigeon industry holds promise for addressing both economic and nutritional needs.

METHODS

To explore umami peptides and their molecular binding mechanisms with umami receptor type 1 member 1 in pigeon meat, an enzymatic hydrolysate product is isolated, analyzed, and subjected to sensory evaluation. Fifteen peptides with high freshness characteristics are separated and identified by ultrafiltration, gel separation, reverse performance liquid chromatography, and nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS/MS).

RESULTS

The molecular docking results show that the amino acid residue Glu128 is a common ligand binding site for all of the fresh-flavored peptides to taste T1R1/T1R3 receptors and it exerts freshness-presenting effects with 15 fresh-flavored peptides through hydrogen bonding, electrostatic interactions, salt bridges, and hydrophobic interactions.

CONCLUSION

This study provides a theoretical basis and technical support for the subsequent development of flavor peptide products in pigeon meat.

A comprehensive review of plant-derived salt substitutes: Classification, mechanism, and application

The diseases caused by excessive sodium intake derived from NaCl consumption have attracted widespread attention worldwide, and many researchers are committed to finding suitable ways to reduce sodium intake during the dietary process. Salt substitute is considered an effective way to reduce sodium intake by replacing all/part of NaCl in food without reducing the saltiness while minimizing the impact on the taste and acceptability of the food. Plant-derived natural ingredients are generally considered safe and reliable, and extensive research has shown that certain plant extracts or specific components are effective salt substitutes, which can also give food additional health benefits. However, these plant-derived salt substitutes (PSS) have not been systematically recognized by the public and have not been well adopted in the food industry. Therefore, a comprehensive review of PSS, including its material basis, flavor characteristics, and taste mechanism is helpful for a deeper understanding of PSS, accelerating its research and development, and promoting its application.

Gamma-glutamylation of beef protein hydrolysates to improve its overall taste and functions of gastro-intestinal hormone (CCK and GLP-1) pro-secretion and anti-inflammation

γ-Glutamylation of beef protein hydrolysate (BPH) by L-glutaminase was carried out to improve the taste, as well as enhance the stimulating effect of gastrointestinal hormone (CCK and GLP-1) secretion and the anti-inflammatory property. Results of sensory evaluation showed that the kokumi taste, umaminess, saltiness of the γ-glutamylated product (γ-GBPH) were significantly higher (p < 0.05), whilst the bitterness was remarkably decreased (p < 0.05) than that of BPH. γ-GBPH had a better promoting effect (p < 0.05) on CCK and GLP-1 secretion and a higher inhibition (p < 0.05) on TNF-α and IL-8 production than BPH in vitro cell experiments. In γ-GBPH, 15 γ-Glutamylated amino acids (γ-[Glu](n =1/2)-AAs) and 10 γ-Glutamyl-tripeptide (γ-Glu-AA-AAs) were synthesized from the bitter amino acids and bitter peptides, respectively, and their total production yield was 140.01-170.46 mg/g and 149.06 mg/g, respectively. The synthesized γ-Glu-AA-AAs entered the binding pocket of the calcium-sensitive receptor (CaSR), and they all interacted with three reported amino acid residues (Ser147, Ala168, and Ser170) of CaSR.

Advances in flavor peptides with sodium-reducing ability: A review

Condiments (such as sodium chloride and glutamate sodium) cause consumers to ingest too much sodium and may lead to a variety of diseases, thus decreasing their quality of life. Recently, a salt reduction strategy using flavor peptides has been established. However, the development of this strategy has not been well adopted by the food industry. There is an acute need to screen for peptides with salty and umami taste, and to understand their taste characteristic and taste mechanism. This review provides a thorough analysis of the literature on flavor peptides with sodium-reducing ability, involving their preparation, taste characteristic, taste mechanism and applications in the food industry. Flavor peptides come from a wide range of sources and can be sourced abundantly from natural foods. Flavor peptides with salty and umami tastes are mainly composed of umami amino acids. Differences in amino acid sequences, spatial structures and food matrices will cause different tastes in flavor peptides, mostly attributed to the interaction between peptides and taste receptors. In addition to being used in condiments, flavor peptides have also anti-hypertensive, anti-inflammatory and anti-oxidant abilities, offering the potential to be used as functional ingredients, thus making their future in the food industry extremely promising.

Synthesis of taste active γ-glutamyl peptides with pea protein hydrolysate and their taste mechanism via in silico study

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.

Generation of kokumi γ-glutamyl short peptides in Spanish dry-cured ham during its processing

The typical dry-cured ham flavor is rich in umami and brothy perceptions, for which short peptides may contribute. Particularly, γ-glutamyl peptides could be the responsible of these previously reported attributes, as they exert a synergistic interaction with other basic tastes and modify the intensity of salty, sweet, and umami tastes. The content of peptides has been reported to evolve along the processing, but no kokumi γ-glutamyl peptides have been identified in Spanish dry-cured hams yet. In this research, nine γ-glutamyl dipeptides (γ-EA, γ-EC, γ-EE, γ-EF, γ-EL, γ-EM, γ-EV, γ-EW, and γ-EY) and two γ-glutamyl tripeptides (GSH and γ-EVG) have been quantitated at 6, 12, 18 and 24 months of traditional processing of Spanish dry-cured ham by performing a Q Exactive Orbitrap-based tandem mass spectrometry. The results show an increase of γ-EA, γ-EE, γ-EF, γ-EL, γ-EM and γ-EVG, obtaining maximums at 24 months of curing ranging from 0.14 (γ-EVG) to 18.86 (γ-EL) μg/g dry-cured ham. Otherwise, γ-EV, γ-EW and γ-EY accumulated until the 18th month of storage to 15.10, 0.54 and 3.17 μg/g dry-cured ham, respectively; whereas γ-EC and GSH amounts decreased starting from 0.0676 and 4.41 μg/g dry-cured ham, respectively at earlier stages. The concentration dynamics of these compounds may be linked with proteolytic and oxidative reactions during processing. In addition, due to their synergistic effect on kokumi activity, this could constitute insights of the brothy perceptions of dry-cured ham, and these peptides probably contribute to the sensory differences existing in long processed Spanish dry-cured hams.

Identifying Umami Peptides Specific to the T1R1/T1R3 Receptor via Phage Display

Umami peptides are small molecular weight oligopeptides that play a role in umami taste attributes. However, the identification of umami peptides is easily limited by environmental conditions, and the abundant source and high chromatographic separation efficiency remain difficult. Herein, we report a robust strategy based on a phage random linear heptapeptide library that targets the T1R1-Venus flytrap domain (T1R1-VFT). Two candidate peptides (MTLERPW and MNLHLSF) were readily identified with high affinity for T1R1-VFT binding (KD of MW-7 and MF-7 were 790 and 630 nM, respectively). The two peptides exhibited umami taste and significantly enhanced the umami intensity when added to the monosodium glutamate solution. Overall, this strategy shows that umami peptides could be developed via phage display technology for the first time. The phage display platform has a promising application to discover other taste peptides with affinity for taste receptors of interest and has more room for improvement in the future.

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

Umami peptides have currently become the research focus in the food umami science field and the key direction for umami agent development. This is because umami peptides have good processing characteristics, umami and nutritional values. We here used virtual screening (including online enzymolysis through ExPASy PeptideCutter, bioactivity screening using the PeptideRanker, toxicity and physicochemical property prediction using Innovagen and ToxinPred software), molecular docking, and electronic tongue analysis to identify umami peptides generated from Atlantic cod myosin. Twenty-three putative umami peptides were screened from the myosin. Molecular docking results suggested that these 23 peptides could enter the binding pocket in the T1R3 cavity, wherein Glu128 and Asp196 were the main amino acid residues, and that hydrogen bonding and electrostatic interactions were the main binding forces. Twelve synthetic peptides tested on the electronic tongue exhibited umami taste and a synergistic effect with monosodium glutamate (MSG). Among them, GGR, AGCD, and SGDAW had higher umami intensities than the other peptides, while SGDAW and NDDGW exhibited stronger umami-enhancing capabilities in 0.1% MSG solution. This study offers a method for the rapid screening of umami peptides from marine protein resources and places the foundation for their application in the food industry.