The flavor-enhancing action of glutamate and its mechanism involving the notion of kokumi

Molecular simulation screening and sensory evaluation unearth a novel kokumi compound with bitter-masking effect: N-lauroyl-L-tryptophan

N-lauroyl-L-tryptophan (LT), which has the strongest potential flavor-presenting activity, was skillfully screened from numerous N-Lau-AAs docked to different taste receptors by molecular simulation techniques. Subsequently, LT was synthesized employing food-grade commercial enzymes and structurally characterized, the optimized yields of LT could reach 69.08%, 76.16%, and 50.40%, respectively. Sensory and E-tongue evaluations showed that LT at 1 mg/L significantly benefited the performance of different taste sensations and exhibited different bitter taste masking effects: L-Ile (68.42%), L-Trp (68.18%), D-salicylic acid (48.48%) and quinine (35.00%). The molecular docking results illustrated that LT had a high affinity for various taste receptors, dominated by hydrogen bonding and hydrophobic interactions. This work provided a rare systematic elucidation of the potential and mechanism of enzymatically synthesized LT in enhancing taste properties. It provides novel insights into the directions and strategies for the excavation and innovation of flavor enhancers and food flavors.

Characteristics of kopyor coconut (Cocos nucifera L.) using sensory analysis and metabolomics-based approach

Kopyor is a coconut with unique characteristics from Indonesia, one of the largest coconut producers in the world. Kopyor is an edible mature coconut with soft endosperm. Although this fruit is one of the most popular coconuts in the world, there are limited studies on its properties, including its sensory attributes and metabolite profiles. This study investigates the characteristics of kopyor using sensory evaluation, a widely targeted metabolomics approach, and multivariate analysis. The liquid (water) and solid (flesh) endosperms were collected as the samples. The results showed that kopyor has characteristics that distinguish it from normal mature and young coconuts. Kopyor water has a milky, creamy, nutty, bitter, and astringent taste with an oily aftertaste and mouthfeel. Kopyor flesh is soft and moist and gives a sandy mouth feel. This study analyzed the sensory attributes of the kopyor endosperm for the first time and compared it with those of normal mature and young coconuts. A gas chromatography mass spectrometry analysis showed that kopyor contained wider variety of metabolites than normal coconuts of the same age. Based on the differential analysis and orthogonal projections to latent structures-regression, kopyor water was characterized by the accumulation of flavor-related metabolites, such as amino acids and organic acids, which contributed to its sensory complexity. This study solidified the effects of maturation and endosperm type on metabolite accumulation in kopyor endosperm. This pioneering information will lead to the future use of kopyor and other unique coconuts worldwide for food, contributing to the sustainability of the coconut industry.

Effects of umami substances as taste enhancers on salt reduction in meat products: A review

Sodium is one of the essential additives in meat processing, but excessive sodium intake may increase risk of hypertension and cardiovascular disease. However, reducing salt content while preserving its preservative effect, organoleptic properties, and technological characteristics poses challenges. In this review, the mechanism of salt reduction of umami substances was introduced from the perspective of gustation-taste interaction, and the effects of the addition of traditional umami substances (amino acids, nucleotides, organic acids(OAs)) and natural umami ingredients (mushrooms, seaweeds, tomatoes, soybeans, tea, grains) on the sensory properties of the meat with reduced-salt contents were summarized. In addition, the impacts of taste enhancers on eating quality (color, sensory, textural characteristics, and water-holding capacity (WHC)), and processing quality (lipid oxidation, pH) of meat products (MP) and their related mechanisms were also discussed. Among them, natural umami ingredients exhibit distinct advantages over traditional umami substances in terms of enhancing quality and nutritional value. On the basis of salt reduction, natural umami ingredients improve the flavor, texture, WHC and antioxidant capacity. This comprehensive review may provide the food industry with a theoretical foundation for mitigating salt consumption through the utilization of umami substances and natural ingredients.

Progress in Multisensory Synergistic Salt Reduction

Excessive salt intake, primarily from sodium chloride prevalent in modern food processing, poses a significant public health risk associated with hypertension, cardiovascular diseases and stroke. Researchers worldwide are exploring approaches to reduce salt consumption without compromising food flavor. One promising method is to enhance salty taste perception using multisensory synergies, leveraging gustatory, olfactory, auditory, visual, tactile and trigeminal senses to decrease salt intake while preserving food taste. This review provides a comprehensive overview of salt usage in foods, mechanisms of salty taste perception and evaluation methods for saltiness. Various strategies for reducing salt consumption while maintaining food flavor are examined, with existing salt reduction methods' advantages and limitations being critically analyzed. A particular emphasis is placed on exploring the mechanisms and potential of multisensory synergy in salt reduction. Taste interactions, olfactory cues, auditory stimulation, visual appearance and tactile sensations in enhancing saltiness perception are discussed, offering insights into developing nutritious, appealing low-sodium foods. Furthermore, challenges in current research are highlighted, and future directions for effective salt reduction strategies to promote public health are proposed. This review aims to establish a scientific foundation for creating healthier, flavorful low-sodium food options that meet consumer preferences and wellness needs.

Umami Characteristics and Taste Improvement Mechanism of Meat

Taste is one of the five senses that detect vital information about what we are eating. Comprehending taste is crucial for enhancing the flavor of foodstuffs and high-protein foods like meat. Umami has global recognition as the fifth elementary taste, alongside sweetness, sourness, saltiness, and bitterness. Umami compounds are known to enhance the sensation of recognized flavors such as salty, sweet, bitter, and others. This could end up in greater food consumption by consumption by consumers. With the rising global population, meat consumption is rising and is projected to double by 2025. It is crucial to comprehend the umami mechanism of meat and meat products, identify novel compounds, and employ laboratory methodologies to gather varied information. This knowledge will aid in the development of new consumer products. Although very limited information is available on umami taste and compounds in meat through research data. This article discusses recent advancements in umami compounds in other foodstuff as well as meat to aid in designing future research and meat product development. Moreover, another objective of this review is to learn present techniques in foodstuffs to enhance umami taste and utilize that knowledge in meat products.

Enhancing the palatability of cultivated meat

Cultivated meat (CM) has transitioned from a futuristic concept to a present reality, with select products approved for consumption and sale in Singapore, Israel, and the USA. This evolution has emphasized scalable, cost-effective, and sustainable production, as well as navigation of regulatory pathways. As CM develops, a crucial challenge lies in delivering products that are highly appealing to consumers. Central to this will be refining CM palatability, a term encompassing food's taste, aroma, texture, tenderness, juiciness, and color. We explore the scientific and engineering approaches to producing palatable CM, including cell-line selection, cell differentiation, and post-processing techniques. This includes a discussion of the structural and compositional properties of meat that are intrinsically coupled to palatability.

Novel kokumi peptides from yeast extract and their taste mechanism via an in silico study

Yeast extract, a widely utilized natural substance in the food industry and biopharmaceutical field, holds significant potential for flavor enhancement. Kokumi peptides within yeast extracts were isolated through ultrafiltration and gel chromatography, followed by identification using liquid chromatography tandem mass spectrometry (LC-MS/MS). Two peptides, IQGFK and EDFFVR, were identified and synthesized using solid-phase methods based on molecular docking outcomes. Sensory evaluations and electronic tongue analyses conducted with chicken broth solutions revealed taste thresholds of 0.12 mmol L-1 for IQGFK and 0.16 mmol L-1 for EDFFVR, respectively, and both peptides exhibited kokumi properties. Additionally, through molecular dynamics simulations, the binding mechanisms between these peptides and the calcium-sensing receptor (CaSR) were explored. The findings indicated stable binding of both peptides to the receptor. IQGFK primarily interacted through electrostatic interactions, with key binding sites including Asp275, Asn102, Pro274, Trp70, Tyr218, and Ser147. EDFFVR mainly engaged via van der Waals energy and polar solvation free energy, with key binding sites being Asp275, Ile416, Pro274, Arg66, Ala298, and Tyr218. This suggests that both peptides can activate the CaSR, thereby inducing kokumi activity. This study provides a theoretical foundation and reference for the screening and identification of kokumi peptides, successfully uncovering two novel kokumi peptides derived from yeast extract.

Noteworthy Consensus Effects of D/E Residues in Umami Peptides Used for Designing the Novel Umami Peptides

Aspartic acid (D) and glutamic acid (E) play vital roles in the umami peptides. To understand their exact mechanism of action, umami peptides were collected and cut into 1/2/3/4 fragments. Connecting D/E to the N/C-termini of the fragments formed D/E consensus effect groups (DEEGs), and all fragments containing DEEG were summarized according to the ratio and ranking obtained in the above four situations. The interaction patterns between peptides in DEEG and T1R1/T1R3-VFD were compared by statistical analysis and molecular docking, and the most conservative contacts were found to be HdB_277_ARG and HdB_148_SER. The molecular docking score of the effector peptides significantly dropped compared to that of their original peptides (-1.076 ± 0.658 kcal/mol, p value < 0.05). Six types of consensus fingerprints were set according to the Top7 contacts. The exponential of relative umami was linearly correlated with ΔGbind (R2 = 0.961). Under the D/E consensus effect, the electrostatic effect of the umami peptide was improved, and the energy gap between the highest occupied molecular orbital-the least unoccupied molecular orbital (HOMO-LUMO) was decreased. The shortest path map showed that the peptides had similar T1R1-T1R3 recognition pathways. This study helps to reveal umami perception rules and provides support for the efficient screening of umami peptides based on the material richness in D/E sequences.

Highly sensitive determination of L-glutamic acid in pig serum with an enzyme-free molecularly imprinted polymer on a carbon-nanotube modified electrode

Through electrochemical polymerization using L-glutamic acid (L-Glu) as a template and 4,6-diaminoresorcinol as a functional monomer, an enzyme-free molecularly imprinted polymer (MIP) based L-Glu sensor with multi-walled carbon nanotubes (MWCNTs) decorated on a glassy carbon electrode (GCE), namely G-MIP/MWCNTs/GCE, was developed in this work. The reaction conditions were optimized as follows: electrochemical polymerization of 23 cycles, pH of 3.0, molar ratio of template/monomer of 1 : 4, volume ratio of elution reagents of acetonitrile/formic acid of 1 : 1, and elution time of 2 min. The prepared materials and molecularly imprinted polymer were characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) as well as electrochemical methods. The electrochemical properties of different electrodes were investigated via differential pulse voltammetry (DPV), showing that the electrode of G-MIP/MWCNTs/GCE exhibited excellent catalytic oxidation activity towards L-Glu. A good linear relationship between peak-currents and L-Glu concentrations in a range from 1.00 × 10-8 to 1.00 × 10-5 mol L-1 was observed, with a detection limit of 5.13 × 10-9 mol L-1 (S/N = 3). The imprinted sensor possesses excellent selectivity, high sensitivity, and good stability, which have been successfully applied for the detection of L-Glu in pig serum samples with a recovery rate of 97.4-105.5%, being comparable to commercial high-performance liquid chromatography, demonstrating a simple, rapid, and accurate way for the determination of L-Glu in the fields of animal nutrition and biomedical engineering.

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.

Taste-taste associations in chemotherapy-induced subjective taste alterations: findings from a questionnaire survey in an outpatient clinic

PURPOSE

Chemotherapy-induced taste alteration is a side effect that can result in malnutrition and reduced quality of life in cancer patients. However, the underlying causes of this phenomenon remain unclear, and evidence-based treatments have not been established. This study focused on patients' subjective symptoms of taste alterations aimed to explore how the sensitivity to basic tastes changes due to anticancer agents and how alterations in one taste perception are associated with changes in other tastes during chemotherapy.

METHODS

A cross-sectional questionnaire-based interview survey was conducted on 215 patients undergoing chemotherapy. The subjective sensitivity to each basic taste was assessed using a visual analog scale, and the incidence of taste alterations due to different chemotherapy regimens was calculated. Multivariate logistic regression analysis was performed to determine whether there were associations between changes in one taste sensitivity and changes in other taste sensitivities.

RESULTS

Approximately half (49.5%) of the patients experienced chemotherapy-induced taste alterations. An analysis of subjective changes in basic tastes revealed that the salt and umami taste systems were more sensitive to chemotherapy than other taste systems. Patients with altered sensitivity to sweet taste were significantly more likely to report altered sensitivity to salt, bitter, and sour tastes. Moreover, umami-salt and bitter-sour taste sensitivities were significantly related to each other.

CONCLUSION

This study suggests that changes in subjective sensitivities to one basic taste during chemotherapy may be accompanied by changes in other tastes in specific combinations. Considering taste associations in dietary guidance may help improve the nutritional status of cancer patients experiencing taste alterations due to chemotherapy.

Quality Evaluation of Shiitake Blanched and Centrifuged Broths as Functional Instant Drinks

In the process of making mushrooms into vacuum-fried crisps, the resulting blanched broth (BB) and centrifuged broth (CB) are often discarded, thereby increasing the amount of wastewater and treatment costs. This study measured the proximate compositions, bioactive components, taste components, and minerals of freeze-dried BB and CB and then used functional indigestible dextrin (Fibersol-2) as a carrier to make these two broths into instant drinks. The solids of the BB and CB contained protein (16.88-19.21%), fat (0.01-0.23%), ash (12.89-13.50%), carbohydrate (67.28-70.00%), sugars and polyols (40.55-45.68%), free amino acids (6.58-6.69%), 5'-nucleotides (0.98-1.47%), and bioactive components, especially polysaccharides (4.53-7.45%), ergothioneine (both 0.19%), and total phenols (0.15-0.36%). The equivalent umami concentration of BB was 2.77-fold higher than that of the CB. Both BB and CB showed compositions and essential minerals that are rich in taste. Using a nine-point hedonic test, it was found that the solid contents of BB and CB in the instant drink affected the consumer's preference. The flavor and overall preference of instant drinks with 2.5% BB or CB were the best amongst consumers. Overall, the BB and CB were rich in nutrients and bioactive and taste components and could be developed as a functional food in the form of a drink.

Interkingdom Detection of Bacterial Quorum-Sensing Molecules by Mammalian Taste Receptors

Bitter and sweet taste G protein-coupled receptors (known as T2Rs and T1Rs, respectively) were originally identified in type II taste cells on the tongue, where they signal perception of bitter and sweet tastes, respectively. Over the past ~15 years, taste receptors have been identified in cells all over the body, demonstrating a more general chemosensory role beyond taste. Bitter and sweet taste receptors regulate gut epithelial function, pancreatic β cell secretion, thyroid hormone secretion, adipocyte function, and many other processes. Emerging data from a variety of tissues suggest that taste receptors are also used by mammalian cells to "eavesdrop" on bacterial communications. These receptors are activated by several quorum-sensing molecules, including acyl-homoserine lactones and quinolones from Gram-negative bacteria such as Pseudomonas aeruginosa, competence stimulating peptides from Streptococcus mutans, and D-amino acids from Staphylococcus aureus. Taste receptors are an arm of immune surveillance similar to Toll-like receptors and other pattern recognition receptors. Because they are activated by quorum-sensing molecules, taste receptors report information about microbial population density based on the chemical composition of the extracellular environment. This review summarizes current knowledge of bacterial activation of taste receptors and identifies important questions remaining in this field.