Impact of obstructive sleep apnea syndrome on olfactory and gustatory capacity.

Only a few studies have investigated olfactory function in patients with obstructive sleep apnea syndrome (OSAS) using psychophysical testing, and there is a scarcity of data regarding taste evaluation in the existing literature. The primary objectives of this study were to assess both smell and taste in patients with OSAS and to explore the correlation between the severity of symptoms and sensory perception. A total of 85 OSAS patients and a control group comprising 81 subjects were enrolled. Initial assessments included anamnesis, nasal endoscopy, and the completion of questionnaires (Epworth Sleepiness Scale, Visual Analogue Scale, Questionnaire of Olfactory Disorders, and the importance of olfaction questionnaire). The diagnosis of OSAS was confirmed by polysomnography, while nasal airflow was evaluated using rhinomanometry. Olfaction was assessed using the Sniffin' Sticks test, and the Threshold-Discrimination-Identification (TDI) score was calculated. Taste evaluation was conducted in a subgroup of participants (42 patients, 38 controls) using taste strips. The mean TDI score was 31 ±â€…5.6 for OSAS patients and 35 ±â€…4.6 for controls, indicating a significant difference (P < 0.001). Similarly, the taste score was 7 ±â€…3.0 for OSAS patients and 12.6 ±â€…3.2 for controls (P < 0.001). No correlations were observed between TDI and Apnea Hypopnea Index (AHI) (r = -0.12; P = 0.28), as well as between the taste score and AHI (r = -0.31; P = 0.22). However, a weak but significant correlation between TDI score and Epworth Sleepiness Scale was detected (r = -0.05; P = 0.002). The study revealed a significant decrease in sensory perception among patients with OSAS, though open questions persist about the pathophysiology.

Determination of objective taste perception among Iranian medical sciences students during COVID­19 pandemic in Yazd, Eastern Iran: a case-control pilot study.

BACKGROUND: Taste disorders in patients suffering from COVID-19 were popular. Some people even after recovery report residual effects of loss of smell and taste. This study aimed to investigate the taste Perception of Iranian Medical Sciences students during the COVID-19 pandemic. METHODS: The case-control study evaluated 50 Medical Sciences students with a history of COVID-19 infection, as confirmed by the Novel Coronavirus (2019-nCOV) CFX96™ Real-Time PCR Detection System. The other participants consisted of 50 volunteer students with COVID-19 negative. The taste perception was measured with 4 different concentrations of the basic tastes. The stimuli were applied to the protruded tongue. Subjects were asked to identify the researcher when they felt the taste. Data are expressed as frequency distribution and analyzed with the Chi-Square test (P < 0.05). RESULTS: In this survey, 54% of participants were male and 46% were female, the mean age of participants was 22.96 ± 5 years. The results showed a significant difference in the sweet and bitter taste perception score according to the history of dietary supplement use. The bitter taste perception score declared a considerable difference since COVID-19 infection. There was no significant difference between the taste perception in the two studied groups for all 4 basic tastes according to gender, COVID-19 infection status, history of taste and smell disorders, and the elapsed time since COVID-19 infection. CONCLUSION: Our findings could provide important insights into taste perception. The history of dietary supplementation may influence how sweetness and saltiness are perceived. There was a noticeable difference in bitter taste perception depending on the time that had elapsed since the most recent COVID-19 infection.

Effects of weight change on taste function; a systematic review.

BACKGROUND: The aim of this review is to evaluate the relationship between weight status and taste perception and preference of sweet, salt, fat, bitter, and sour through reviewing observational and interventional studies with objective methods. METHODS: A comprehensive literature search was performed in 6 online databases of PubMed, Scopus, Web of Science, Cochrane, Embase, and Google Scholar up to October 2021. The following keywords were used in the search strategy: (Taste OR "Taste Perception" OR "Taste Threshold" OR "Taste preference" OR "Taste sensitivity" OR "Taste changes") AND (weight OR "Weight gain" OR "weight loss" OR "weight change"). RESULTS: Most observational studies indicate that four taste sensitivities or perceptions (especially sweet and salt taste perception) are lower in subjects with overweight and obesity. The longitudinal studies reported that sweet and fat preference is increased along with weight gain in adults. It is concluded that taste perceptions are decreased in individuals with overweight and obesity, especially in men. Also, taste perception and preference change after weight loss but not significantly. CONCLUSION: It is suggested that the results of the interventional studies are not conclusive and need further studies with the same and standard design adjusting cofounding variables including genetic, gender, age and food condition of subjects.

[Determinants of salt taste threshold among urban residents: the KOBE study].

Objectives　Though having a high salt taste threshold has been associated with hypertension, its exact determinants remains unclear. This study aimed to identify the determinants of salt taste threshold in a community-based population and to determine the relationship between salt taste thresholds and the simultaneous presence of multiple determinants.Methods　Of the 1,117 participants of the baseline survey of the Kobe study, a cohort study of healthy urban residents, aged 40-74 years, with no history of cancer or cardiovascular diseases, nor undergoing treatment for hypertension, diabetes, or dyslipidemia, was conducted. Among them, 1,116 underwent the salt taste threshold test, and urine samples were collected to determine their estimated salt intake. The salt taste threshold test was carried out using SALSAVE®, with a salt taste threshold of 0.6% defined as normal, and that of 0.8% or more defined as high. A binomial logistic regression model was used, with high salt taste threshold as the objective variable, and life and family status, education, smoking and alcohol drinking status, intake status of salt dried fish, stress indicators, and daily salt intake (estimated from the urine sample) as the explanatory variables. A binomial logistic regression analysis was conducted, through multivariate analysis using the forced entry method, with factors influencing salt taste threshold as explanatory variables, and salt taste threshold (normal/high) as the objective variable. This analysis was performed excluding the urinary sodium-to-potassium ratio to account for multicollinearity with the estimated daily salt intake.Results　The mean age was 60.9±9.0 years for men, and 58.0±8.7 years for women. The salt taste threshold was normal in 80.9% (n=903) of the participants (73.6% [n=251] men and 84.1% [n=652] women), and high in 19.1% (n=213) of the participants (26.3% [n=90] men and 15.9% [n=123] women). Multivariate analysis revealed that smoking habits were significantly associated with a higher salt taste threshold, with an odds ratio (95% confidence interval) of 2.51 (1.33-4.74) for all participants. The odds ratio for a high salt taste threshold was 1.45 (1.03-2.03) for the top 25% estimated daily salt intake group, showing a significant association with a high salt taste threshold. In the analysis by sex, smoking habits were associated with higher salt taste thresholds, while an association with estimated daily salt intake was observed only in men.Conclusion　Smoking status and estimated daily salt intake were associated with higher salt taste thresholds in healthy urban residents.

Evaluation of masticatory behavior and taste sensitivity after pacifier removal in preschool children: a 1-year follow-up.

OBJECTIVE: The aim was to investigate the influence of pacifier removal on the development of masticatory function and taste sensitivity in preschool children. METHODS: Sixty children (mean age 48.2 months) were divided into two groups: pacifier group (n = 28) and a control group (n = 32), which were evaluated and followed up for a period of 12 months (at baseline, 6 months, and 1 year). Masticatory and swallowing functions were assessed using the Mastication Observation and Evaluation (MOE) protocol and Orofacial Myofunctional Rating (MBGR), respectively. Detection thresholds for sucrose and urea were measured by the staircase method. The two-way ANOVA mixed model was used for time*group interaction analysis. RESULTS: MOE scores improved significantly over time in both groups, although a significant difference between groups persisted after 1 year. On the other hand, swallowing scores were significantly different at baseline, but within 1 year, the scores were no longer different between groups. Chewing time and the number of cycles were not different between groups and both decreased after 1 year. Sucrose sensitivity was significantly greater in the control group at baseline and changed over time (p < 0.05), being no longer different between groups after 6 months. Bitter sensitivity did not differ over time nor between groups. CONCLUSIONS: Detection threshold for sucrose differed significantly between children with and without pacifier habit at a mean age of 42 months. Total masticatory function did not self-correct after sucking habit removal within a 1-year period. CLINICAL RELEVANCE: Children with pacifier habit showed important changes in masticatory function that did not self-correct 1 year after cessation of the habit, highlighting the need for prevention and habit interruption as early as possible.

Changes in taste and food preferences in breast cancer patients receiving chemotherapy: a pilot study.

PURPOSE: Cancer treatment may relate to appetite reduction and malnutrition. We investigated taste alterations and dish-type preferences during chemo- and/or radiation therapy in breast cancer patients. METHODS: Breast cancer patients (BC, n = 59) scheduled to receive cancer therapy and healthy subjects (control group or CTRL, n = 49) were voluntarily recruited. Taste detection thresholds (DTs) and recognition thresholds (RT) were compared between pre-treatment BC patients and CTRL for sweet (sucrose), salty (NaCl), bitter (caffeine), and sour (citric acid) solutions. Changes in taste thresholds and dish preferences during treatment were monitored in the BC group. Blood chemistry and anthropometric data were collected. RESULTS: At baseline, BC patients demonstrated lower sweet and salty DTs and RTs and a higher sour RT compared to CTRL. Bitter DT and RT were similar in both groups. Mild/soft dishes were preferred over fried/oily dishes by BC patients. Throughout treatment in BC patients, sweet thresholds significantly declined, while salty, bitter, and sour DTs and RTs were not affected, and there was no increase in preference for a dish. However, preference towards mild/soft dishes remained. While sweet-sour fruits and sweetened nuts were not favored during therapy. CONCLUSIONS: Sensitivities to sweet, salty, and sour but not bitter tastes differed between BC patients and CTRL. During treatment, sweet taste sensitivity increased while other tastes were unaffected. BC patients preferred mild/soft dishes over fried and sweetened dishes compared to CTRL. Our findings may contribute to developing dishes for breast cancer patients to increase food intake and thereby lower the risk of malnutrition.

Detection thresholds for quinine, PTC, and PROP measured using taste strips.

PURPOSE: In clinical practice, when ability to perceive bitter taste is studied, quinine is preferred to phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP) as taste stimulus, because many subjects are genetically non-tasters for PTC/PROP. However, it is poorly known how sensitive anterior (front) and posterior (back) parts of the tongue are to different bitter tastants that are detected by different bitter taste receptors (TAS2Rs). In the present study, we aimed to characterize sensitivity to bitter taste at front and back parts of tongue. METHODS: We measured thresholds for quinine, PTC, and PROP using the "taste strips", employing seven concentrations of each stimulus both at front and back parts of tongue in 203 healthy participants (56% females, mean age 28 years). RESULTS: Our data confirmed the hypothesis that the inability to perceive quinine was less frequent than the inability to perceive PTC and PROP: People can still perceive the bitter taste of quinine even if they are "non-tasters" for PROP/PTC. As expected, strong correlations between PTC and PROP thresholds were observed. Interestingly, correlations between thresholds for quinine and PTC/PROP also emerged. Overall, the detection thresholds were lower when measured at front part of the tongue. CONCLUSIONS: Our data suggest that determining taster status for quinine using paper "taste strips", applied to front part of the tongue, represents a suitable method for the screening for ageusia for bitter taste.

Taste sensitivity in anorexia nervosa: A systematic review.

OBJECTIVE: There is evidence for altered processing of taste in anorexia nervosa, particularly in the areas of reward processing and hedonic sensitivity. However, research on whether people with anorexia nervosa identify taste stimuli accurately, known as taste sensitivity, has yielded mixed findings. The objective of this study was to synthesize the literature on taste sensitivity in this disorder to provide a basis for future discussion on whether altered taste sensitivity may be also implicated in wider atypical taste processing in anorexia. METHOD: Electronic databases were searched systematically to identify published research examining taste sensitivity in anorexia. Search terms were "anorexia nervosa", or "eating disorder", combined with "taste". 18 studies met inclusion criteria. RESULTS: The review of the findings suggest that individuals with AN may experience reduced taste sensitivity that may improve following recovery. However, there was a significant variability in results across studies, potentially reflecting methodological problems including low sample sizes, experimental designs, and uncontrolled confounding variables. DISCUSSION: This review suggests that altered taste sensitivity could represent a component in the wider altered taste processing observed in anorexia nervosa. However, the heterogeneity of findings highlight the need for future research to consider methodological issues raised by this review.

Longitudinal study of factors affecting taste sense decline in old-old individuals.

The sense of taste plays a pivotal role for personal assessment of the nutritional value, safety and quality of foods. Although it is commonly recognised that taste sensitivity decreases with age, alterations in that sensitivity over time in an old-old population have not been previously reported. Furthermore, no known studies utilised comprehensive variables regarding taste changes and related factors for assessments. Here, we report novel findings from a 3-year longitudinal study model aimed to elucidate taste sensitivity decline and its related factors in old-old individuals. We utilised 621 subjects aged 79-81 years who participated in the Septuagenarians, Octogenarians, Nonagenarians Investigation with Centenarians Study for baseline assessments performed in 2011 and 2012, and then conducted follow-up assessments 3 years later in 328 of those. Assessment of general health, an oral examination and determination of taste sensitivity were performed for each. We also evaluated cognitive function using Montreal Cognitive Assessment findings, then excluded from analysis those with a score lower than 20 in order to secure the validity and reliability of the subjects' answers. Contributing variables were selected using univariate analysis, then analysed with multivariate logistic regression analysis. We found that males showed significantly greater declines in taste sensitivity for sweet and sour tastes than females. Additionally, subjects with lower cognitive scores showed a significantly greater taste decrease for salty in multivariate analysis. In conclusion, our longitudinal study revealed that gender and cognitive status are major factors affecting taste sensitivity in geriatric individuals.

Determinants of Obesity in Italian Adults: The Role of Taste Sensitivity, Food Liking, and Food Neophobia.

Recent evidence has suggested that factors related to sensory perception may explain excess weight. The objective of this study was to consider multiple aspects while investigating the phenomenon of obesity. One goal was to compare taste acuity (taste threshold and density of fungiform papillae) in both normal weight and obese subjects. Thresholds for 4 basic tastes and the fat stimulus were investigated. A second research goal was to study the relationship between food neophobia and food liking according to the body mass index and taste sensitivity. The results showed that obese subjects seem to have higher threshold values and a reduced number of fungiform papillae than do normal weight subjects. Food neophobia did not vary with nutritional status, whereas differences were found for food liking, with obese subjects showing significantly higher liking ratings for high energy dense products compared with normal weight subjects.

Impact of self-tongue brushing on taste perception in Thai older adults: A pilot study.

Oral hygiene influences taste, affecting appetite and nutrition in older adults. However, the impact of self-administered tongue brushing on their taste perceptions was unclear. This pilot study (N = 44) was aimed to observe the changes in taste thresholds using Filter Paper Disc after tongue brushing in Thai older adults. Based on the results, continuous tongue brushing for 3 months reduced tongue coat (p < 0.01) and improved subjective taste in 74% of participants. Sweet and salty recognition thresholds were reduced in both anterior and posterior tongue, while sour and bitter thresholds were reduced only in posterior tongue. No changes in umami (savory) were observed. Daily brushing was more effective than weekly brushing in improving the sweet and bitter tastes. The data suggested that tongue brushing could improve perception of multiple tastes and daily tongue brushing was recommended as routine personal care for older adults. This study supports further investigation in a randomized-controlled setting.

Alcoholic beverage strength discrimination by taste may have an upper threshold.

BACKGROUND: Given the association between alcohol consumption and negative health consequences, there is a need for individuals to be aware of their consumption of ethanol, which requires knowledge of serving sizes and alcoholic strength. This study is one of the first to systematically investigate the ability to discriminate alcoholic strength by taste. METHODS: Nine discrimination tests (total n = 413) according to International Standardization Organization (ISO) 4120 sensory analysis methodology "triangle test" were performed. RESULTS: A perceptible difference was found for vodka in orange juice (0.0 vs. 0.5% vol; 0 vs. 1% vol), pilsner and wheat beer (0.5 vs. 5% vol), and vodka in orange juice (5 vs. 10% vol, 20 vs. 30% vol, and 30 vs. 40% vol). The percentage of the population perceiving a difference between the beverages varied between 36 and 73%. Alcoholic strength (higher vs. lower) was correctly assigned in only 4 of the 7 trials at a significant level, with 30 to 66% of the trial groups assigning the correct strength. For the trials that included beverages above 40% vol (vodka unmixed, 40 vs. 50% vol and vodka in orange juice, 40 vs. 50% vol), testers could neither perceive a difference between the samples nor assign correct alcoholic strength. CONCLUSIONS: Discrimination of alcoholic strength by taste was possible to a limited degree in a window of intermediate alcoholic strengths, but not at higher concentrations. This result is especially relevant for drinkers of unlabeled, over-proof unrecorded alcoholic beverages who would potentially ingest more alcohol than if they were to ingest commercial alcohol. Our study provides strong evidence for the strict implementation and enforcement of labeling requirements for all alcoholic beverages to allow informed decision making by consumers.

Salt taste sensitivity thresholds in adolescents: are there any relationships with body composition and blood pressure levels?

The aim of this study was to identify the salt taste sensitivity thresholds and relationships with body composition and blood pressure levels in a cross-sectional study of adolescents. Blood pressure and body composition were measured with a digital device and by anthropometry, respectively. The salt taste sensitivity threshold was measured with 9 solutions with different sodium chloride concentrations to assess the sensitivity to saltiness. The solutions (4, 8, 15, 30, 60, 120, 250, 500 and 1000 mmol/L sodium chloride) were served in increasing concentrations until the taste was correctly identified. The taste sensitivity threshold was then classified as normal or high. In total, 421 adolescents (55.6% female), with an average age of 15.8 ± 0.91 years, were evaluated. The median threshold was 30 mmol/L, and 36.1% had a high threshold. The high blood pressure prevalence was 12.6%, and 25.5% of the subjects were overweight. When the mean systolic and diastolic blood pressure levels were compared between the normal and increased threshold groups after adjusting for gender, age, sedentary lifestyle and body mass index, only diastolic blood pressure showed a statistically significant effect (P < 0.0001) between the groups. The effect of a high threshold on body composition after adjusting for gender, age and physical inactivity was not significant (P = 0.177). There was no relationship between a high threshold and systolic pressure or body composition in the evaluated adolescents; therefore, only diastolic blood pressure was affected.

Not salt taste perception but self-reported salt eating habit predicts actual salt intake.

Excessive dietary salt intake is related to cardiovascular morbidity and mortality. Although dietary salt restriction is essential, it is difficult to achieve because of salt palatability. However, the association between salt perception or salt eating habit and actual salt intake remains uncertain. In this study, we recruited 74 healthy young individuals. We investigated their salt-eating habits by questionnaire and salt taste threshold through a rating scale that used serial dilution of a sodium chloride solution. Predicted 24-hr urinary salt excretions using Kawasaki's and Tanaka's equations estimated dietary salt intake. Participants' mean age was 35 yr, and 59.5% were male. Salt sense threshold did not show any relationship with actual salt intake and a salt-eating habit. However, those eating "salty" foods showed higher blood pressure (P for trend=0.048) and higher body mass index (BMI; P for trend=0.043). Moreover, a salty eating habit was a significant predictor for actual salt intake (regression coefficient [ß] for Kawasaki's equation 1.35, 95% confidence interval [CI] 10-2.69, P=0.048; ß for Tanaka's equation 0.66, 95% CI 0.01-1.31, P=0.047). In conclusion, a self-reported salt-eating habit, not salt taste threshold predicts actual salt intake.

Tongue-on-a-Chip: Parallel Recording of Sweet and Bitter Receptor Responses to Sequential Injections of Pure and Mixed Sweeteners.

A microfluidic tongue-on-a-chip platform has been evaluated relative to the known sensory properties of various sweeteners. Analogous metrics of typical sensory features reported by human panels such as sweet taste thresholds, onset, and lingering, as well as bitter off-flavor and blocking interactions were deduced from the taste receptor activation curves and then compared. To this end, a flow cell containing a receptor cell array bearing the sweet and six bitter taste receptors was transiently exposed to pure and mixed sweetener samples. The sample concentration gradient across time was separately characterized by the injection of fluorescein dye. Subsequently, cellular calcium responses to different doses of advantame, aspartame, saccharine, and sucrose were overlaid with the concentration gradient. Parameters describing the response kinetics compared to the gradient were quantified. Advantame at 15 µM recorded a significantly faster sweetness onset of 5 ± 2 s and a longer lingering time of 39 s relative to sucrose at 100 mM with an onset of 13 ± 2 s and a lingering time of 6 s. Saccharine was shown to activate the bitter receptors TAS2R8, TAS2R31, and TAS2R43, confirming its known off-flavor, whereas addition of cyclamate reduced or blocked this saccharine bitter response. The potential of using this tongue-on-a-chip to bridge the gap with in vitro assays and taste panels is discussed.

Association between underweight and taste sensitivity in middle- to old-aged nursing home residents in Sri Lanka: a cross-sectional study.

Low taste sensitivity may be one factor related to undernutrition, which is a major problem in developing countries. The purpose of this cross-sectional study was to examine the association between underweight, one indicator of undernutrition, and taste sensitivity in middle- to old-aged Sri Lankan nursing home residents. Participants were 946 residents with BMI of <25·0 from 25 nursing homes. Data were obtained on height, weight, taste sensitivity, subjective taste ability, sex, age, ethnicity, number of years in nursing homes, activities of daily living (ADL), frequency of exercise, bowel movements, smoking status, drinking status, current number of chronic diseases, number and kinds of medications used, self-reporting questionnaire 20 (SRQ20), subjective smell ability, number of teeth present, Eichner index and flow rate of saliva. Low sensitivity to bitter taste, being male, old age, low ADL, smoking experience, drinking experience, fewer medications used and no use of medication for hypertension and diabetes were each associated with underweight (P < 0·05). In a multilevel Poisson regression model adjusted for sex, age, ADL, smoking status, drinking status, number of medications used, use of medication for hypertension and diabetes and flow rate of saliva, subjects with low sensitivity (>0·003% quinine hydrochloride dihydrate) to bitter taste had a significant 1·70 times higher prevalence ratio (95% confident interval 1·04-2·80) for underweight compared with those with high sensitivity (0·0001% quinine hydrochloride dihydrate). These results suggest that low taste sensitivity to bitter taste may be one factor related to underweight.

Gustatory dysfunction in euthyroid primary hypothyroidism.

Objectives: The study assessed gustatory functions in patients with primary hypothyroidism who are euthyroid on supplemental hormone therapy with levothyroxine over six months' duration and to evaluate the association of gustatory dysfunction, if any, with the serum TSH levels. Design: This analytical community-based cross-sectional study was conducted in April 2021, following participants' ethical approval and written informed consent. Setting: The study was conducted in a tertiary health care centre in Bangalore, Karnataka, India. Participants: Sixty-eight subjects participated in this study: 34 primary hypothyroid patients and an equal number of healthy controls. Interventions: Gustatory sensations were assessed by the triple drop test, and scores were given depending on the identification of the tastants (sweet, sour, salty, and bitter). The taste scores were compared, and the association between TSH levels and gustatory parameters were evaluated. Results: Overall taste scores were lesser in hypothyroid patients. This finding depicted that their taste thresholds were increased and were statistically significant (p < 0.001), though the association between the degree of hypogeusia and TSH levels was not statistically significant. Conclusion: Patients with primary hypothyroidism can suffer from hypogeusia, which may revert to normal once they achieve euthyroid status with levothyroxine supplementation. However, this has not been conclusively shown in studies. Our study concluded that hypogeusia was present in primary hypothyroidism despite patients being euthyroid on hormone supplementation, and it was not dependent on the serum TSH levels. Funding: None declared.

Identification and Verification of Novel Umami Peptides Isolated from Hybrid Sturgeon Meat (Acipenser baerii × Acipenser schrenckii).

To explore the umami mechanism in sturgeon meat, five peptides (ERRY, VRGPR, LKYPLE, VKKVFK, and YVVFKD) were isolated and identified by ultrafiltration, gel filtration chromatography, and UPLC-QTOF-MS/MS. The omission test confirmed that the five umami peptides contributed to the umami taste of sturgeon meat. Also, the peptides had the double effective role of enhancing both umami and saltiness. The threshold of ERRY was only 0.031, which exceeded most umami peptides in the last 3 years. Molecular docking results showed that five peptides could easily bind to Gly167, Ser170, and Try218 residues in T1R3 through hydrogen bonds and electrostatic interactions. Furthermore, molecular dynamics simulations indicated that hydrogen bonds and hydrophobic interactions were the main intermolecular interaction forces. This study could contribute to revealing the umami taste mechanism of sturgeon meat and provide new insights for effective screening of short umami peptides.

Human Gingival Fibroblasts as a Novel Cell Model Describing the Association between Bitter Taste Thresholds and Interleukin-6 Release.

Human gingival fibroblast cells (HGF-1 cells) present an important cell model to investigate the gingiva's response to inflammatory stimuli such as lipopolysaccharides from Porphyromonas gingivalis (Pg-LPS). Recently, we demonstrated trans-resveratrol to repress the Pg-LPS evoked release of the pro-inflammatory cytokine interleukin-6 (IL-6) via involvement of bitter taste sensing receptor TAS2R50 in HGF-1 cells. Since HGF-1 cells express most of the known 25 TAS2Rs, we hypothesized an association between a compound's bitter taste threshold and its repressing effect on the Pg-LPS evoked IL-6 release by HGF-1 cells. To verify our hypothesis, 11 compounds were selected from the chemical bitter space and subjected to the HGF-1 cell assay, spanning a concentration range between 0.1 µM and 50 mM. In the first set of experiments, the specific role of TAS2R50 was excluded by results from structurally diverse TAS2R agonists and antagonists and by means of a molecular docking approach. In the second set of experiments, the HGF-1 cell response was used to establish a linear association between a compound's effective concentration to repress the Pg-LPS evoked IL-6 release by 25% and its bitter taste threshold concentration published in the literature. The Pearson correlation coefficient revealed for this linear association was R2 = 0.60 (p < 0.01), exceeding respective data for the test compounds from a well-established native cell model, the HGT-1 cells, with R2 = 0.153 (p = 0.263). In conclusion, we provide a predictive model for bitter tasting compounds with a potential to act as anti-inflammatory substances.

Identification of Novel Umami Peptides in Chicken Breast Soup through a Sensory-Guided Approach and Molecular Docking to the T1R1/T1R3 Taste Receptor.

Ultrafiltration combined with nanoliquid chromatography quadrupole time-of-flight mass spectrometry (nano-LC-QTOF-MS) and sensory evaluation was used to separate and identify umami peptides in chicken breast soup. Fifteen peptides with umami propensity scores of >588 were identified from the fraction (molecular weight ≤1 kDa) using nano-LC-QTOF-MS, and their concentrations ranged from 0.02 ± 0.01 to 6.94 ± 0.41 µg/L in chicken breast soup. AEEHVEAVN, PKESEKPN, VGNEFVTKG, GIQKELQF, FTERVQ, and AEINKILGN were considered as umami peptides according to sensory analysis results (detection threshold: 0.18-0.91 mmol/L). The measurement of point of subjective equality showed that these six umami peptides (2.00 g/L) were equivalent to 0.53-0.66 g/L of monosodium glutamate (MSG) in terms of umami intensity. Notably, the sensory evaluation results showed that the peptide of AEEHVEAVN significantly enhanced the umami intensity of the MSG solution and chicken soup models. The molecular docking results showed that the serine residues were the most frequently observed binding sites in T1R1/T1R3. The binding site Ser276 particularly contributed to the formation of the umami peptide-T1R1 complexes. The acidic glutamate residues observed in the umami peptides were also involved in their binding to the T1R1 and T1R3 subunits.