Suppression of hTAS2R16 Signaling by Umami Substances

Chemical, Sensory Variations in Black Teas from Six Tea Cultivars in Jingshan, China

The development of black tea quality is the outcome of the synergistic interaction between tea cultivars and the ecological environment of the production area, including factors such as climate, soil, and cultivation practices. Nevertheless, within a specific geographical region, systematic analysis of the environmental regulation mechanisms governing processing adaptability and quality formation among different cultivars remains insufficient. This study evaluated six Camellia sinensis cultivars from the Jingshan region of Hangzhou, China, integrating non-targeted metabolomics, sensory profiling, bioassays, and molecular docking to elucidate cultivar-specific quality attributes. Non-volatile metabolomics identified 84 metabolites linked to color and taste, including amino acids, catechins, flavonoid glycosides, and phenolic acids. Sensory and metabolite correlations revealed that amino acids enhanced brightness and imparted fresh-sweet flavors, while catechins contributed to bitterness and astringency. Specific metabolites, such as 4-hydroxybenzoyl glucose and feruloyl quinic acid, modulated color luminance. Volatile analysis identified 13 aroma-active compounds (OAV ≥ 1), with 1-octen-3-ol, phenylacetaldehyde, and linalool endowing JK with distinct floral-fruity notes. Molecular docking further demonstrated interactions between these volatiles and olfactory receptors (e.g., OR1A1 and OR2J2), providing mechanistic insights into aroma perception. These findings establish a robust link between cultivar-driven metabolic profiles in black tea, offering actionable criteria for cultivar selection and quality optimization in regional tea production.

Biochanin a modulates steroidogenesis and cellular metabolism in human granulosa cells through TAS2Rs activation: a spotlight on ovarian function

BACKGROUND

Endocrine-disrupting chemicals (EDCs) interfere with the endocrine system and negatively impact reproductive health. Biochanin A (BCA), an isoflavone with anti-inflammatory and estrogen-like properties, has been identified as one such EDC. This study investigates the effects of BCA on transcription, metabolism, and hormone regulation in primary human granulosa cells (GCs), with a specific focus on the activation of bitter taste receptors (TAS2Rs).

METHODS

Primary human GCs from 60 participants were treated with 10 µM BCA, and selective antagonists were used to block TAS2R activation. The study assessed the expression of TAS2R14 and TAS2R43, and analyzed the impact on StAR and CYP17A1 gene expression. Intracellular calcium levels, lipid droplet size, and mitochondrial network complexity were measured to evaluate cellular metabolism and energy dynamics.

RESULTS

BCA treatment significantly upregulated TAS2R14 and TAS2R43 expression, leading to a 70% increase in StAR mRNA levels and a twofold increase in CYP17A1 expression (p < 0.05). These effects were reversed by TAS2R antagonists. Additionally, BCA treatment decreased intracellular Ca2+ levels (p < 0.01) and reduced lipid droplet size (p < 0.001), both of which were counteracted by antagonists. Enhanced mitochondrial network complexity (p < 0.001) was also observed, suggesting increased mitochondrial fusion and improved cellular energy dynamics.

CONCLUSION

The findings indicate that BCA modulates transcriptional and metabolic processes in GCs through the activation of TAS2Rs, highlighting their role in endocrine regulation. The statistically significant results emphasize the relevance of further exploring the effects of EDCs like BCA on reproductive health. Collaborative research efforts are essential to address and mitigate the adverse impacts of EDCs on fertility.

Umami and saltiness enhancements of vegetable soup by enzyme-produced glutamic acid and branched-chain amino acids

Introduction

One major challenge of reducing salt content in food is the risk of the overall taste becoming bland. Enhancing saltiness is an effective strategy for salt reduction, and the development of salt-reduced foods using these saltiness-enhancing flavorants as food additives is underway. However, an increasing number of consumers demand a reduction in additives in clean-label foods.

Objective

Enzyme processing of food is an attractive strategy for developing clean-label foods because enzymes are not considered additives. We aimed to improve the saltiness and umami intensity of vegetable soups by enzyme treatment while meeting clean-label requirements. We first optimized the enzymatic reaction conditions of a protease and glutaminase blend and then investigated the synergistic effects of this enzyme blend on the taste of vegetable soup.

Results

Sensory evaluations indicated that the reaction products (e.g., protein hydrolysates or amino acids) could enhance the umami, kokumi, and saltiness intensity of vegetable soup supplemented with 0.5% NaCl. Notably, the saltiness intensity ratio of the enzyme-treated soup with 0.50, 0.45, and 0.40% NaCl were increased by 1.31-, 1.16-, and 0.99-fold, respectively, when this ratio for the control soup with 0.50% NaCl was set to 1.0. This indicates a 20% salt reduction rate can be achieved by enzyme treatment. Moreover, we found that these enhancements were synergically caused by enzyme-produced glutamic acid and branched-chain amino acids.

Conclusion

Our findings suggest that using enzyme blends of bacterial and fungal proteases and glutaminase is an effective approach to enhancing the saltiness levels of vegetable soups while meeting clean-label requirements.

Taste Sensor Assessment of Bitterness in Medicines: Overview and Recent Topics

In recent decades, taste sensors have been increasingly utilized to assess the taste of oral medicines, particularly focusing on bitterness, a major obstacle to patient acceptance and adherence. This objective and safe method holds promise for enhancing the development of patient-friendly medicines in pharmaceutical companies. This review article introduces its application in measuring the intensity of bitterness in medicine, confirming the achievement of taste masking, distinguishing taste differences between branded and generic medicines, and identifying substances to suppress bitterness in target medicines. Another application of the sensor is to predict a significant increase in bitterness when medicine is taken with certain foods/beverages or concomitant medication. Additionally, to verify the sensor's predictability, a significant correlation has been demonstrated between the output of a bitter-sensitive sensor designed for drug bitterness (BT0) and the bitterness responses of the human taste receptor hT2R14 from BitterDB (huji.ac.il). As a recent advancement, a novel taste sensor equipped with lipid/polymer membranes modified by 3-Br-2,6-dihydroxybenzoic acid (2,6-DHBA), based on the concept of allostery, is introduced. This sensor successfully predicts the bitterness of non-charged pharmaceuticals with xanthine skeletons, such as caffeine or related compounds. Finally, the future prospects of taste sensors are discussed.

Influence of Sodium Chloride on Human Bitter Taste Receptor Responses

In the past, taste interactions between sodium chloride (NaCl) and bitter tastants were investigated in human sensory studies, and the suppression of bitterness by sodium was observed. It is currently not clear if this phenomenon occurs predominantly peripherally or centrally and if the effect is general or only particular bitter compounds are blocked. Therefore, the influence of NaCl at the receptor level was tested by functional expression assays using four out of ∼25 human bitter taste receptors together with prototypical agonists. It was observed that NaCl affected only the responses of particular bitter taste receptor-compound pairs, whereas other bitter responses remained unchanged upon variations of the sodium concentrations. Among the tested receptors, TAS2R16 showed a reduction in signaling in the presence of NaCl. This demonstrates that for some receptor-agonist pairs, NaCl reduces the activation at the receptor level, whereas central effects may dominate the NaCl-induced bitter taste inhibition for other substances.

Inhibitors of human bitter taste receptors from the five-flavour berry, Schisandra chinensis

The human bitter taste 2 receptor member 16 (TAS2R16) is one of 25 class A G-protein-coupled receptors (GPCRs) and responds to a variety of molecules responsible for the bitter taste sensation perceived in humans. TAS2R16 can be activated by β-glucopyranosides, and its activation can be inhibited by probenecid, a synthetic drug compound used to treat gout. In this study we describe naturally derived compounds which can inhibit the activation of TAS2R16 by salicin in vitro. These compounds belong to the lignan class derived from the fruit of Schisandra chinensis, which is commonly known as the five-flavour berry. We further tested other analogs with this lignan scaffold, found their differential inhibitory activities towards TAS2R16 in vitro, and sought to rationalize the activity using molecular docking of these lignans on a computationally modelled structure of TAS2R16. Selected lignans with inhibitory activity against other TAS2Rs reveal sub-millimolar inhibitory activity towards TAS2R10, TAS2R14, and TAS2R43 in cell-based assays. These compounds with demonstrated in vitro inhibition of bitter taste receptors may serve as tool compounds to investigate the molecular mechanisms of hTAS2Rs biology in gustatory and non-gustatory tissues.

Aquafeed fermentation improves dietary nutritional quality and benefits feeding behavior, meat flavor, and intestinal microbiota of Chinese mitten crab (Eriocheir sinensis)

Normally, proper fermentation can be an efficient and widely used method to improve feed quality in animal rearing; however, the studies on crustaceans, especially Eriocheir sinensis, remain limited. This study aimed to investigate whether feed fermentation could meliorate dietary nutritional value and benefit E. sinensis rearing. First, non-fermented feed (NFD) and fermented feed (FD) were produced and assessed, respectively. Then, the "Y" maze feed choice behavior test (180 times; 30 times, 6 rounds) was conducted to assess the attractiveness of these 2 feeds for crabs. Finally, a total of 80 crabs (44.10 ± 0.80 g) were randomly assigned into 2 groups with 4 replicates, and fed the experimental diets for 8 weeks to evaluate the effects of each feed on growth, antioxidant capacity, meat flavor, and intestinal microbiota. In this study, FD showed higher levels of crude protein (P < 0.01), soluble protein (P < 0.01), amino acids (P < 0.05), lactic acid (P < 0.001), and lower levels of crude fiber (P < 0.05) and antinutritional factors (agglutinin, trypsin inhibitor, glycinin, and β-conglycinin) (P < 0.001) than NFD. Additionally, FD was more attractive to crabs than NFD (P < 0.01) and it stimulated the appetite of crabs more than NFD (P < 0.05). The growth performance, feed efficiency, and digestive enzyme activity of FD-fed crabs were significantly higher than those of NFD-fed crabs (P < 0.05). The electronic sensory measurements and free amino acid profiles revealed that the FD diet had positive impacts on the meat flavor of crabs, particularly in "sweet" and "umami" tastes. Moreover, the antioxidant capacity of FD-fed crabs was significantly higher than that of NFD-fed crabs (P < 0.05). Fermented feed also affected the diversity and composition of intestinal microflora. The functional prediction of microbial communities showed that crabs fed FD had a better microecological environment in the intestine. In conclusion, the fermentation of aquafeed could be an effective approach to enhance feed quality and therefore benefit E. sinensis rearing.

Revealing the Secret of Umami Taste of Peptides Derived from Fermented Broad Bean Paste

To understand the umami taste of fermented broad bean paste (FBBP) and explore the umami mechanism, eight peptides (PKALSAFK, NKHGSGK, SADETPR, EIKKAALDANEK, DALAHK, LDDGR, and GHENQR) were separated and identified via ultrafiltration, RP-HPLC, and UPLC-QTOF-MS/MS methods. Sensory experiments suggested that eight novel peptides showed umami/umami-enhancing and salt-enhancing functions. Significantly, the threshold of EIKKAALDANEK in aqueous solution exceeded that of most umami peptides reported in the past 5 years. The omission test further confirmed that umami peptides contributed to the umami taste of FBBP. Molecular docking results inferred that all peptides easily bind with Ser, Glu, His, and Asp residues in T1R3 through hydrogen bonds and electrostatic interactions. The aromatic interaction, hydrogen bond, hydrophilicity, and solvent-accessible surface (SAS) were the main interaction forces. This work may contribute to revealing the secret of the umami taste of FBBP and lay the groundwork for the efficient screening of umami peptides.

Isolation, identification and sensory evaluation of kokumi peptides from by-products of enzyme-modified butter

BACKGROUND

Enzyme-modified butter is used as a common raw material to obtain a natural milk flavor. Butter protein is a by-product in butter processing that can be used as substrate to produce taste-active peptides, which can create additional value and new application opportunities, making the method more environmentally friendly.

RESULTS

Putative kokumi peptides from hydrolysates of protein by-products were isolated by gel filtration chromatography and reversed-phase high-performance liquid chromatography. The isolated peptide fraction with the most pronounced kokumi taste was screened by sensory evaluation and electronic tongue analysis. Eleven peptides were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Six peptides were synthesized to verify their taste characteristics. Five synthetic peptides (FTKK, CKEVVRNANE, EELNVPG, VPNSAEER and YPVEPFTER) showed different intensity levels of kokumi taste. Of these peptides, the decapeptide CKEVVRNANE had the highest kokumi intensity.

CONCLUSION

The newly identified kokumi peptides increased the kokumi taste intensity and showed some synergistic effect with umami taste. Both termini of the peptides seem to play an important role in taste characteristic. Glu residue at both termini can increase the kokumi taste intensity. This work indicated that it was feasible to produce kokumi peptides by enzymatic hydrolysis of the protein by-products of butter. © 2022 Society of Chemical Industry.

Isolation, identification and characterization of taste peptides from fermented broad bean paste

Pixian broad-bean paste (PBBP) is a famous fermented condiment in China, which may produce abundant flavor peptides during fermentation process. Herein, the tasteful peptides from fermented broad-bean (FB) were separated...

An update on extra-oral bitter taste receptors

Bitter taste-sensing type 2 receptors (TAS2Rs or T2Rs), belonging to the subgroup of family A G-protein coupled receptors (GPCRs), are of crucial importance in the perception of bitterness. Although in the first instance, TAS2Rs were considered to be exclusively distributed in the apical microvilli of taste bud cells, numerous studies have detected these sensory receptor proteins in several extra-oral tissues, such as in pancreatic or ovarian tissues, as well as in their corresponding malignancies. Critical points of extra-oral TAS2Rs biology, such as their structure, roles, signaling transduction pathways, extensive mutational polymorphism, and molecular evolution, have been currently broadly studied. The TAS2R cascade, for instance, has been recently considered to be a pivotal modulator of a number of (patho)physiological processes, including adipogenesis or carcinogenesis. The latest advances in taste receptor biology further raise the possibility of utilizing TAS2Rs as a therapeutic target or as an informative index to predict treatment responses in various disorders. Thus, the focus of this review is to provide an update on the expression and molecular basis of TAS2Rs functions in distinct extra-oral tissues in health and disease. We shall also discuss the therapeutic potential of novel TAS2Rs targets, which are appealing due to their ligand selectivity, expression pattern, or pharmacological profiles.

Spices, Condiments, Extra Virgin Olive Oil and Aromas as Not Only Flavorings, but Precious Allies for Our Wellbeing

Spices, condiments and extra virgin olive oil (EVOO) are crucial components of human history and nutrition. They are substances added to foods to improve flavor and taste. Many of them are used not only to flavor foods, but also in traditional medicine and cosmetics. They have antioxidant, antiviral, antibiotic, anticoagulant and antiinflammatory properties and exciting potential for preventing chronic degenerative diseases such as cardiomyopathy and cancer when used in the daily diet. Research and development in this particular field are deeply rooted as the consumer inclination towards natural products is significant. It is essential to let consumers know the beneficial effects of the daily consumption of spices, condiments and extra virgin olive oil so that they can choose them based on effects proven by scientific works and not by the mere illusion that plant products are suitable only because they are natural and not chemicals. The study begins with the definition of spices, condiments and extra virgin olive oil. It continues by describing the pathologies that can be prevented with a spicy diet and it concludes by considering the molecules responsible for the beneficial effects on human health (phytochemical) and their eventual transformation when cooked.

Trp-Trp acts as a multifunctional blocker for human bitter taste receptors, hTAS2R14, hTAS2R16, hTAS2R43, and hTAS2R46

Many functional food ingredients activate human bitter taste receptors (hTAS2Rs). In this study, A novel inhibitor, Trp-Trp, for hTAS2R14 was identified by searching for the agonist peptide's analogs. Trp-Trp also inhibited hTAS2R16, hTAS2R43, and hTAS2R46, which share the same agonists with hTAS2R14. The multifunctional characteristic of Trp-Trp is advantageous for use as bitterness-masking agents in functional foods.