Taste Sensitivity Research Articles

Peri-threshold Trigeminal Stimulation with Capsaicin Increases Taste Sensitivity in Humans

IntroductionTaste perception is affected by trigeminal stimuli, i.e., capsaicin. This has been studied at suprathreshold concentrations. However, little is known about taste perception at threshold level in the presence of low concentration of capsaicin. The aim of the study was to explore whether taste sensitivity for sweet, sour, salt, bitter, and umami is modulated by the presence of capsaicin in the peri-threshold range.MethodsFifty-seven adults (age range 19–85 years; 32 women) with functional gustation participated in the study. Based on their perception of phenylthiocarbamide (PTC), the group was stratified into non-tasters (n = 20) and tasters (n = 37). Threshold for sweet (sucrose), sour (citric acid), salty (sodium chloride), bitter (quinine-hydrochloride), and umami (sodium-glutamate) tastes was estimated using a single-staircase paradigm (3-alternative forced choice; volume per trial 0.1 ml) with or without 0.9-µM capsaicin added. This capsaicin concentration had been determined in pilot studies to be in the range of oral perception thresholds.ResultsThe addition of capsaicin produced lower taste thresholds for sweet, sour, salty, and bitter but not for umami. In contrast, neither PTC taster status nor sex affected these results.ConclusionThe current results indicate that a low concentration of capsaicin increases gustatory sensitivity.ImplicationsThe current findings provide evidence supporting different effects of capsaicin on taste perception at threshold level. It has implications for boosting taste sensitivity or flavor enjoyment with low concentration of capsaicin.

Change in Taste Preference to Capsaicin and Catechin Due to Aging in Mice.

Taste is a chemical sensation that primarily detects nutrients present in food, and maintenance of taste sensations is important for ensuring that older people have a balanced nutritional diet. While several reports have suggested that taste sensitivity changes with age, the molecular mechanisms underlying this phenomenon are still unclear. Previous studies on the matter have focused mainly on the relationship between aging and taste detection of specific basic taste-inducing substances, and other than for these basic substances, understanding of how aging affects the detection of taste is limited. Therefore, to understand the effect that aging has on the taste detection of some familiar substances found in our daily meals, namely capsaicin and catechin, we investigated age-related changes in taste preferences to capsaicin and catechin in young and old C57BL/6J mice using a 48-h two-bottle preference test. For the capsaicin stimuli, the mice showed avoidance behavior in a concentration-dependent manner. However, we observed that there was no significant difference in the preference ratio for capsaicin between young and old mice. For the catechin stimuli, although both age groups showed avoidance behavior in a concentration-dependent manner, the preference ratio in old mice showed significantly higher values than those in young mice. This suggests that catechin sensitivity is declined due to aging. Thus, we observed that catechin sensitivity decreases with age, but capsaicin sensitivity does not.

Genetic Variation in Taste Receptor Genes (SCNN1B, TRPV1) and Its Correlation with the Perception of Saltiness in Normotensive and Hypertensive Adults.

Background Different taste preferences correlated with genetic variations may lead to food consumption patterns that contribute to nutrient-related health outcomes such as hypertension. Objectives The aim of this study was to determine whether single nucleotide polymorphisms (SNPs) in the salt taste receptor genes SCNN1B and TRPV1 affect salt taste perception among normotensive and hypertensive people. Materials and Methods We conducted a cross-sectional case control study by design consisting of a normotensive and hypertensive group. Participants were 253 adults with age range of 20–82 residing in Mississippi, USA. For each of 128 normotensives and 125 hypertensives, the salt taste recognition threshold and salt taste receptor genotype were determined. Results The hypertensive group had a higher salt taste recognition threshold than the normotensive group (P < 0.001). The polymorphism of TRPV1, rs4790522, with the AA genotype was associated with a higher salt recognition threshold (lower salt taste sensitivity) in people with hypertension and obesity. Moreover, the polymorphism of TRPV1, rs8065080, and SCNN1B, rs239345, genes were associated with a risk of hypertension (P=0.016 and P=0.024). Conclusion Correlations between SNPs, salt taste sensitivity, and hypertension risk were observed. People with hypertension had a higher salt taste threshold than those with normotension.

Relationship between taste sensitivity and dental caries

Relationship between taste sensitivity and dental caries

Impact of Very Hot Drink Consumption Habits, Age, and Sex, on Taste Sensitivity.

The temperature range for consuming hot drinks includes temperatures that can damage cells on the tongue. We hypothesized that the consumption of very hot drinks can lead to a decrease in the ability to perceive low concentrations of tastants. We evaluated the ability to perceive low concentrations of five prototypical sapid compounds in 42 women and 40 men aged 18–65. A questionnaire made it possible to collect the usual frequencies (number of unit/day) and consumption temperature levels (medium hot/very hot) for four very common hot drinks (coffee, tea, herbal infusions, and hot chocolate). Our results showed that subjects who consumed very hot drinks (versus medium hot) were less sensitive to sweet (p = 0.020) and salty (p = 0.046) tastes. An aggravating effect of high consumption frequencies was only shown for sweet taste (p = 0.036). Moreover, our data also showed that women were more sensitive than men to sour, bitter, and umami tastes (p values < 0.05), as well as that taste sensitivity decreases with age, especially after 50 years old (all tastes; p values < 0.05). These findings strengthen our knowledge about the influence of sex and age on taste sensitivity, and they provide knowledge on the influence of consumption habits related to hot drinks on taste sensitivity.

Sensory Processing Dysfunction and Mealtime Behavior Problems in Children With Autism

To compare sensory processing and mealtime problem behaviors among children with autism spectrum disorder (ASD) and typically developing controls, and to examine the relationship between atypical sensory processing and eating problems in children with ASD. 50 children (4-10 years) with a diagnosis of ASD as per DSM-5 were recruited from the pediatric psychology clinic of a tertiary care center in India. The Brief Assessment of Mealtime Behavior in Children (BAMBIC) and the Short Sensory Profile (SSP) were administered to measure feeding and sensory processing problems, respectively. Parents were interviewed about their child's dietary intake using a 3-day dietary recall. The ASD group showed greater mealtime behavior problems than the control group and had significantly higher total scores on the BAMBIC (P<0.001), and on two of the three subscales including food refusal (P<0.001) and disruptive behavior (P<0.001). The ASD group, relative to the neurotypical children, showed atypical response on majority of the subscales of the short sensory profile including tactile sensitivity (P<0.001), taste sensitivity (P<0.001), movement sensitivity (P<0.001), under responsiveness (P<0.001), auditory filtering (P<0.001), low weak/energy (P=0.02), and visual/auditory sensitivity (P<0.001). The study underscores the need for detailed evaluation of sensory processing and feeding problems of children with ASD so that the interventions can be tailored to address their unique sensory characteristics.

Taste Sensitivity and Taste Preference among Malay Children Aged 7 to 12 Years in Kuala Lumpur-A Pilot Study.

The taste and food preferences in children can affect their food intake and body weight. Bitter and sweet taste sensitivities were identified as primary taste contributors to children’s preference for consuming various foods. This pilot study aimed to determine the taste sensitivity and preference for bitter and sweet tastes in a sample of Malaysian children. A case–control study was conducted among 15 pairs of Malay children aged 7 to 12 years. Seven solutions at different concentrations of 6-n-propylthiouracil and sucrose were prepared for testing bitterness and sweet sensitivity, respectively. The intensity of both bitter and sweet sensitivity was measured using a 100 mm Labelled Magnitude Scale (LMS), while the taste preference was rated using a 5-point Likert scale. The participants were better at identifying bitter than sweet taste (median score 6/7 vs. 4/7). No significant differences were detected for both tastes between normal-weight and overweight groups (bitter: 350 vs. 413, p = 0.273; sweet: 154 vs. 263, p = 0.068), as well as in Likert readings (bitter 9 vs. 8: p = 0.490; sweet 22 vs. 22: p = 0.677). In this sample of Malay children, the participants were more sensitive to bitterness than sweetness, yet presented similar taste sensitivity and preference irrespective of their weight status. Future studies using whole food samples are warranted to better characterize potential taste sensitivity and preference in children.

Kokumi taste perception is functional in a model carnivore, the domestic cat (Felis catus)

Kokumi taste is a well-accepted and characterised taste modality and is described as a sensation of enhancement of sweet, salty, and umami tastes. The Calcium Sensing Receptor (CaSR) has been designated as the putative kokumi taste receptor for humans, and a number of kokumi-active ligands of CaSR have been discovered recently with activity confirmed both in vivo and in vitro. Domestic cats (Felis catus) are obligate carnivores and accordingly, their diet is abundant in proteins, peptides, and amino acids. We hypothesised that CaSR is a key taste receptor for carnivores, due to its role in the detection of different peptides and amino acids in other species. Using in silico, in vitro and in vivo approaches, here we compare human CaSR to that of a model carnivore, the domestic cat. We found broad similarities in ligand specificity, but differences in taste sensitivity between the two species. Indeed our in vivo data shows that cats are sensitive to CaCl2 as a kokumi compound, but don’t show this same activity with Glutathione, whereas for humans the reverse is true. Collectively, our data suggest that kokumi is an important taste modality for carnivores that drives the palatability of meat-derived compounds such as amino acids and peptides, and that there are differences in the perception of kokumi taste between carnivores and omnivores.

17 Use of hair cortisol analysis to evaluate the influence of housing conditions on long-term stress in horses

Horses are kept in a variety of housing systems which often reflect the needs of both horses and their owners as well as available resources. Housing management practices not only impact horse health and performance but may also influence a horse's physiological and psychological stress. Traditional sampling methods using blood, saliva, urine, and feces are often utilized to evaluate stress in animals by measuring acute cortisol levels. Hair cortisol analysis allows for the quantification of long-term cortisol which may be a better indicator of prolonged periods of elevated stress. The objectives of this study were to evaluate the influence of transitioning horses from outdoor group housing to individual box stalls on hair cortisol concentrations (HCC) and determine the relationship between physiological and behavioral stress responses. Hair samples were collected approximately every 30 d from the same location on 11 Quarter Horses (5 mares, 6 geldings; 3.5 ± 1.3 yr) over a period of 180 d (90d group housing/90d box stalls). Hair cortisol production was measured via enzyme-linked immunosorbent assay (ELISA) and horse heart rate (HR) and behavior were recorded throughout a series of novel object and sensory sensitivity tests. Data were analyzed using PROC MIXED and Pearson correlations in SAS v. 9.4. HCC ranged from 0.6 pg/mg to 3.0 pg/mg throughout the study with an average concentration of 1.3 ± 0.4 pg/mg. Overall, there was no difference in HCC due to the type of housing system. However, HCC increased during the 30-d period immediately following the transition from group housing to individual housing and then decreased during the next 30 d period ( P < 0.05). These results suggest that the horses in this study experienced an increase in physiological stress due to the change in housing system but were able to adapt to their new environment. Interestingly, HCC were influenced by the color of the horse's mane and tail ( P < 0.01). Analysis of the relationship between physiological and behavioral responses during the novel object and sensory sensitivity tests revealed mixed results. Horse HR and reactivity were positively correlated during both sound sensitivity tests ( P < 0.05). However, behavioral observations and reactivity during the novel object, smell, and taste sensitivity tests were influenced by the stimulus ( P < 0.05). As behavioral responses may not always reflect physiological responses and only provide short-term measures of stress, hair cortisol has the potential to serve as a biomarker of long-term stress in horses and provides a tool to monitor the effects of management practices such as housing systems.

The Tryptophan/Kynurenine Pathway: A Novel Cross-Talk between Nutritional Obesity, Bariatric Surgery and Taste of Fat.

Diet-induced obesity (DIO) reduces the orosensory perception of lipids in rodents and in some humans. Although bariatric surgery partially corrects this alteration, underlying mechanisms remain poorly understood. To explore whether metabolic changes might explain this fat taste disturbance, plasma metabolome analyses, two-bottle choice tests and fungiform papillae (Fun) counting were performed in vertical sleeve gastrectomized (VSG) mice and sham-operated controls. An exploratory clinic study was also carried out in adult patients undergone a VSG. In mice, we found that (i) the VSG reduces both the plasma neurotoxic signature due to the tryptophan/kynurenine (Trp/Kyn) pathway overactivation and the failure of fat preference found in sham-operated DIO mice, (ii) the activity of Trp/Kyn pathway is negatively correlated to the density of Fun, and (iii) the pharmacological inhibition of the Kyn synthesis mimics in non-operated DIO mice the positive effects of VSG (i.e., decrease of Kyn synthesis, increase of Fun number, improvement of the fat taste perception). In humans, a reduction of the plasma Kyn level is only found in patients displaying a post-surgery improvement of their fat taste sensitivity. Altogether these data provide a plausible metabolic explanation to the degradation of the orosensory lipid perception observed in obesity.

Food Preferences and Obesity.

Obesity is a multifactorial disease with several potential causes that remain incompletely understood. Recent changes in the environment, which has become increasingly obesogenic, have been found to interact with individual factors. Evidence of the role of taste responsiveness and food preference in obesity has been reported, pointing to a lower taste sensitivity and a higher preference and intake of fat and, to a lesser extent, sweet foods in obese people. Studies in the last decades have also suggested that individual differences in the neurophysiology of food reward may lead to overeating, contributing to obesity. However, further studies are needed to confirm these findings. In fact, only a limited number of studies has been conducted on large samples, and several studies were conducted only on women. Larger balanced studies in terms of sex/gender and age are required in order to control the confounding effect of these variables. As many factors are intertwined in obesity, a multidisciplinary approach is needed. This will allow a better understanding of taste alteration and food behaviours in obese people in order to design more effective strategies to promote healthier eating and to prevent obesity and the related chronic disease risks.

Finding the Differences in Capillaries of Taste Buds between Smokers and Non-Smokers Using the Convolutional Neural Networks

Taste function and condition may be a tool that exhibits a rapid deficit to impress the subject with an objectively measured effect of smoking on his/her own body, because smokers exhibit significantly lower taste sensitivity than non-smokers. This study proposed a visual method to measure capillaries of taste buds with capillaroscopy and classified the difference between smokers and non-smokers through convolutional neural networks (CNNs). The dataset was collected from 26 human subjects through the capillaroscopy with the low and high magnification directly; of which 13 were smokers, and the other 13 were non-smokers. The acquired dataset consisted of 2600 images. The results of gradient-weighted class activation mapping (grad-cam) enabled us to understand the difference in capillaries of taste buds between smokers and non-smokers. Through the results, it was found that CNNs gave us a good performance with 79% accuracy. It was discussed that there was a shortage of extracted features when the conventional methods such as structural similarity index (SSIM) and scale-invariant feature transform (SIFT) were used to classify.

Chronic administration of caffeine alters acesulfame-K intake and features of fungiform taste buds in mice

The objective of this study was to investigate the effects of chronic administration of caffeine on the anatomical characteristics of taste buds, the expression level of taste receptor protein in mice, and preference for a palatable solution. We found that following a 21-day administration of caffeine, mice showed increased behavioural responses to sweet stimuli (acesulfame-K solution). Mirroring this behavioural change, chronic caffeine treatment evidently decreased the maximal cross-sectional area and height of the longitudinal axis of fungiform taste buds, the number of taste cells per fungiform taste bud, and the expression of G protein α-gustducin, while the expression of the sweet taste receptors T1R2 and T1R3 was reversed. Our findings demonstrate that chronic administration of caffeine has an impact on taste sensitivity and changes in taste bud features, which may contribute to the alteration of taste behaviour.

Is sonic hedgehog expression in saliva related to taste sensitivity in adults?

Recent studies have demonstrated the critical role of the sonic hedgehog in the sensory perception of taste. Salivary sonic hedgehog stimulates taste bud stem cells, also acts as a taste bud growth factor, and contributes to the receptors' development and longevity in the taste buds. This study's objective was to investigate the possible relationship between taste sensitivity and sonic hedgehog expression in saliva in normal-weight and pre-obese/obese participants (totally 46 male (47.8%) and female (52.2%) aged 19–44 were recruited). Thresholds for the six tastes (sweet, salty, bitter, sour, umami and fat) were investigated using 3-Alternate Forced Choice Methodology. Saliva was collected with the draining method for sonic hedgehog expression analysis. The results indicated significantly higher thresholds for sweet, bitter and fat in pre-obese /obese adults than normal-weight adults (p<0.05). The sonic hedgehog expression was also lower in pre-obese /obese participants than normal-weight participants (p<0.05). Furthermore, sonic hedgehog expression was higher in hypersensitive participants than hyposensitive participants (p<0.05) only among normal-weight individuals, with no significant difference in sonic hedgehog expression level by taste sensitivity in pre-obese/obese individuals (p>0.05). Sonic hedgehog expression level was negatively correlated with body mass index, sweet, salty, bitter and fat taste threshold. The study results indicated that sonic hedgehog expression level acted on taste sensitivity in normal-weight participants, with greater expression in hypersensitive individuals than hyposensitive individuals.

Comparison between the timing of the occurrence of taste sensitivity changes and short-term memory decline due to aging in SAMP1 mice.

Several studies have suggested that cognitive impairment affects taste sensitivity. However, the mechanism behind this is still unclear. In this study, we focused on short-term memory. Using senescence-accelerated mouse prone 1 (SAMP1) mice, we compared whether the effects of aging are observed earlier in taste sensitivity or short-term memory. We used 8-week-old mice as the young group, and 70- and 80-week-old mice as aged groups. Taste sensitivity was evaluated using a 48-hour two-bottle preference test, and short-term memory was evaluated using the Y-maze test. SAMP1 mice showed apparently changes in taste sensitivity at 70-weeks-old. However, the influence of aging on spontaneous alternation behavior, which is indicative of short-term memory alterations, was not observed in 70-week-old mice. At 80-weeks-old, the influence of aging was observed, and spontaneous alternation behavior was significantly decreased. This suggests that age-dependent changes in taste sensitivity occur prior to short-term memory function decline. In addition, there was no significant influence of aging on the mRNA expression of long-term potentiation-related genes in the hippocampus of 80-week-old mice. Therefore, the age-related decline of short-term memory may not affect taste sensitivity.

Evaluation of gustatory sensitivity of individuals with Type 2 Diabetes Mellitus and their relatives

According to the literature reports of both the sensory loss of individuals with type 2 Diabetes Mellitus and of the importance of family interrelationships in the management of this pathology, there is a demand to evaluate the sensory perception of relatives of individuals with type 2 Diabetes Mellitus. Consequently, the aim of this study was to evaluate sweet taste perception of diabetic individuals and their relatives. Methods: For this purpose, a sample of 150 volunteers was invited to participate, which was composed by individuals of both sexes, aged between 18 and 59 years, equally divided into three groups, constituted with 50 volunteers each: non-diabetic individuals, diabetic individuals and relatives. Furthermore, the glucose concentration of all participants was determined by capillary glycemia, and the diabetic participants were referred to a third-party laboratory to perform the glycated hemoglobin test using the immunoturbidimetric. Moreover, a questionnaire of personal and socio-demographic information was applied to diabetic participants and the sensory perception was evaluated through the test for sweet taste sensitivity. Results: The glycemic levels of the diabetic participants given by the Glycated Hemoglobin (HbA1c) test revealed that the results had a mean of 7.92 + 1.89%, equivalent to 180.60 + 54.52 mg/dL. The threshold was 3.34 g/L for diabetic participants, 2.60 g/L for relatives, and 1.92 g/L for the control group. Conclusions: Therefore, the present study demonstrated that the threshold index for sweet taste perception is higher in individuals with Type 2 Diabetes Mellitus and their relatives when compared to the control group.

Genetics of mouse behavioral and peripheral neural responses to sucrose.

Mice of the C57BL/6ByJ (B6) strain have higher consumption of sucrose, and stronger peripheral neural responses to it, than do mice of the 129P3/J (129) strain. To identify quantitative trait loci (QTLs) responsible for this strain difference and to evaluate the contribution of peripheral taste responsiveness to individual differences in sucrose intake, we produced an intercross (F2) of 627 mice, measured their sucrose consumption in two-bottle choice tests, recorded the electrophysiological activity of the chorda tympani nerve elicited by sucrose in a subset of F2 mice, and genotyped the mice with DNA markers distributed in every mouse chromosome. We confirmed a sucrose consumption QTL (Scon2, or Sac) on mouse chromosome (Chr) 4, harboring the Tas1r3 gene, which encodes the sweet taste receptor subunit TAS1R3 and affects both behavioral and neural responses to sucrose. For sucrose consumption, we also detected five new main-effect QTLs, Scon6 (Chr2), Scon7 (Chr5), Scon8 (Chr8), Scon3 (Chr9), and Scon9 (Chr15), and an epistatically interacting QTL pair Scon4 (Chr1) and Scon3 (Chr9). No additional QTLs for the taste nerve responses to sucrose were detected besides Scon2 (Tas1r3) on Chr4. Identification of the causal genes and variants for these sucrose consumption QTLs may point to novel mechanisms beyond peripheral taste sensitivity that could be harnessed to control obesity and diabetes.

Evolvement of taste sensitivity and taste buds in chickens during selective breeding

Chickens have been reported to have a low taste bud count and thus low taste acuity. However, more recent studies indicate that the earlier reported count of chicken taste buds may have been significantly underestimated. To answer the question of whether the taste sensing system in broiler chickens evolved during the breeding selection over the past decades, we compared the taste sensitivity to bitter and taste buds between a meat-type control strain – the 1955 Athens Canadian Random Bred (ACRB), and a modern high-yielding broiler strain – the 2012 Cobb 500. The behavioral tests showed that the ACRB did not avoid bitter taste solutions of quinine hydrochloride (QHCl) at the examined concentrations (0.5, 1, 2, and 4 mM) (P > 0.05), while the Cobb 500 significantly avoided both the 2 mM and 4 mM QHCl solutions (P < 0.01). The labeling of chicken taste buds using the molecular marker Vimentin revealed that Cobb 500 chickens had a slightly higher number (P < 0.1), but lower density of taste bud clusters in the palate (P < 0.01) and the base of the oral cavity (P < 0.05) compared to the ACRB. We also found that a single amino acid change occurred in the bitter taste receptor T2R7. However, the functional analyses using HEK293T cells transiently expressing T2R7 revealed that the functions of T2R7 were comparable between the two strains. Taken together, our results demonstrated that taste sensitivities could be affected by the selection of the broiler chickens. The modern high-yielding broilers, which have massive feed intake and appetite, had a higher sensitivity to bitter taste stimuli than the meat-type chicken strain which was established decades ago. This evolvement of taste sensitivities may be associated with the alterations of an upper level of taste system, rather than the peripheral taste system, including distribution of taste buds and functions of taste receptors.

THE THREE KEYS TO A MUSICAL TREASURE

The role of music in the upbringing of a harmoniously developed generation is invaluable. Unlike other forms of art, music is a miraculous tool capable of activating a person’s most delicate feelings, emotions, and rich emotional reserves in a person. This article presents the pedagogical aspects of the formation of personality in the lessons of music culture, suggestions on the use of national melodies, the opportunities of our musical heritage, and suggestions on the use of Uzbek classical music in the development of artistic taste of future music teachers. The three aspects of musical activity, namely the ability to listen to music, musical taste, and musical sensitivity, are analyzed as factors that determine the extent to which a music listener or performer’s overall artistic taste has developed. Keywords: music, sound, aesthetic education, piece of music, listening to music, musical taste, musical perception, rhythm, timbre, artistic taste.

Altered Taste Perception for Sodium Chloride in Patients With Primary Aldosteronism: A Prospective Cohort Study.

[Figure: see text].