Fungiform Papillae Density Research Articles

Comparative Quantification of Fungiform Papillae Density and Taste Perception in Anemic and Healthy Controls: A Case-Control Study.

Background Taste perception is crucial for dietary choices, nutrition, and overall health. The human tongue, particularly the fungiform papillae, plays a significant role in taste sensation, especially for sweet and umami flavors. Anemia, a common condition characterized by low hemoglobin levels, can affect sensory perception, including taste. Recent research has begun to explore the relationship between fungiform papillae density and taste perception in individuals with anemia. Objective This study aimed to investigate the comparative quantification of fungiform papillae density and its correlation with taste perception in anemic and healthy individuals, with the goal of understanding the underlying mechanisms linking anemia to taste disturbances. Methods A total of 100 adults (50 anemic and 50 healthy controls) aged 18-65 participated in the study. Demographic data, dietary habits, and medical history were collected. Taste perception was assessed using a taste strip test and psychophysical scaling methods, including magnitude estimation and the method of constant stimuli. Fungiform papillae density was quantified using high-resolution images of the tongue. Statistical analyses, including t-tests and correlation analyses, were conducted to compare the groups and explore relationships between hemoglobin levels, papillae density, and taste perception. Results The study found that anemic individuals had a slightly lower mean fungiform papillae density (49 papillae per square centimeter) compared to healthy controls (57 papillae per square centimeter). In the taste strip test, anemic participants showed reduced accuracy in taste perception, particularly for bitter flavors. However, psychophysical scaling results, as measured by magnitude estimation, revealed no statistically significant difference in subjective taste intensity between the anemic and healthy control groups (p=0.8666). Conclusion The study suggests that while anemic individuals may exhibit reduced fungiform papillae density and altered taste perception, particularly for bitter flavors, the overall subjective perception of taste intensity does not significantly differ from that of healthy controls. These findings contribute to the understanding of taste disturbances in anemia and may inform future diagnostic and therapeutic approaches for managing taste disorders in affected individuals.

Histopathology of the Tongue in a Hamster Model of COVID-19.

With altered sense of taste being a common symptom of coronavirus disease 2019 (COVID-19), our objective was to investigate the presence and distribution of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) within the tongue over the course of infection. Golden Syrian hamsters were inoculated intranasally with SARS-CoV-2 and tongues were collected at 2, 3, 5, 8, 17, 21, 35, and 42 days post-infection (dpi) for analysis. In order to test for gross changes in the tongue, the papillae of the tongue were counted. Paraffin-embedded thin sections of the tongues were labeled for the presence of SARS-CoV-2 antigen. There was no difference in fungiform or filiform papillae density throughout the course of infection. SARS-CoV-2 antigen was observed in the circumvallate papillae taste buds (3-35 dpi) and autonomic ganglia (5-35 dpi), as well as in the serous and mucous salivary glands of the posterior tongue (2-42 dpi). The presence and distribution of SARS-CoV-2 suggest that the virus could cause taste disturbance by infecting the circumvallate taste buds. This effect could be exacerbated by a diminished secretion of saliva caused by infection of the serous salivary glands and the autonomic ganglia which innervate them.

Effects of Adolescent Ethanol Exposure on Taste Sensitivity and Preference in Male and Female Mice

Adolescent alcohol use is prevalent in the U.S. and there is increasing evidence that neural and behavioral consequences of adolescent alcohol use may differentially alter the developing neural circuitry in males and females. Taste has been implicated in the preference for and intake of alcohol and alcohol exposure regulates taste perception. Data from our laboratory indicate that adolescent ethanol exposure (AIE) significantly alters lingual expression of fat and sweet taste receptors and decreases the density of fungiform papillae in male and female mice. The goal of the current study was to examine the effects of adolescent ethanol exposure (AIE) on the taste preference thresholds for fat and sweet tastants in male and female C57/Bl6 mice. Mice (postnatal day (P)27) were exposed to intermittent ethanol vapor or volatilized water. The AIE protocol was run for two, 4-day cycles of 16h in-chamber sessions and 8h out-of-chamber sessions separated by 3 days from P27-P35. Ethanol vapor chambers were maintained to achieve blood alcohol concentrations ~ 200mg/dL. One week following the last ethanol exposure, mice (n=9-10/group) were given access to two bottles, one containing a control solution and one containing increasing concentrations of either sucrose or linoleic acid. A single concentration of sucrose was presented to each mouse for 48 hours [0.1, 0.25, 0.5, 1.0, 2.0, 4.0%]. Following access to all concentrations of sucrose, a single concentration of linoleic acid (in 0.3% Xanthan gum) was presented to each mouse for 48 hours [0.0025, 0.025, 0.25, 0.5, 1.0, 2.0%]. Following access to linoleic acid, each mouse received a solution of 1.0% sucrose plus 0.25% linoleic acid for 24 hours. Total intake of the tastant was determined and the preference for each concentration was calculated. A percent intake of 50% is indicative of no preference between solutions. Mice preferred the sucrose solution to the control solution at all concentrations tested. Males had a higher preference for 0.25% sucrose than females and significant effects of AIE and sex were detected at 2.0% sucrose, with males demonstrating a higher preference for sucrose and mice exposed to AIE exhibiting a higher preference for the sucrose solution. No preference or aversion for lower concentrations of linoleic acid were detected (0.0025-0.25%) in females, however, AIE significantly decreased linoleic acid preference (0.5%, 1.0%, 2.0%) compared to air-exposed females. Linoleic acid preference at concentrations of 0.5% and 1.0% was significantly lower than the preference for the control solution and was considered aversive in females. Males were able to detect linoleic acid at lower concentrations than females, and males exposed to AIE exhibited a higher preference for 0.025% linoleic acid, compared to air-exposed males. Linoleic acid at concentrations of 0.025, 0.25 and 2.0% were significantly lower than the preference for the control solution and were considered aversive in males. In males exposed to AIE, the 1.0% sucrose/0.25% linoleic acid solution was preferred over the control solution. These data support our previous findings that ethanol exposure, using this model, significantly alters taste receptor mRNA expression on the circumvallate papillae and fungiform papillae density in adolescent male and female mice. Further understanding of ethanol’s effect on taste sensitivity is needed to better understand the long-term effects of adolescent ethanol exposure on food and beverage preferences and consumption patterns. NIH AA028011 T.W. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Gene Methylation Affects Salivary Levels of the Taste Buds' Trophic Factor, Gustin Protein.

The salivary protein, Gustin/carbonic anhydrase VI, has been described as a trophic factor responsible for the growth of taste buds. We found, in a genetically homogeneous population, that the polymorphism rs2274333 (A/G) of the Gustin gene is crucial for the full functionality of the protein and is associated with taste sensitivity. However, other studies have failed to find this evidence. Here, we verified if Gustin gene methylation can affect the salivary levels of the protein, also concerning the polymorphism rs2274333 and PROP bitter responsiveness. The Gustin gene methylation profiling and the quantification of the Gustin salivary levels were determined in sixty-six volunteers genotyped for the polymorphism rs2274333 (A/G) (Ser90Gly in the protein sequence). The fungiform papillae density was also determined. The results confirm our earlier observations by showing that AA genotypes had a greater density of fungiform taste papillae, whereas the GG genotypes showed a lower density. We also found variations in the protein levels in the three genotype groups and an inverse relationship between Gustin gene methylation and the salivary levels of the protein, mostly evident in AA and ST volunteers, i.e., in volunteers who would be carriers of the functional isoform of the protein. These findings could justify the conflicting data in the literature.

Methods for fungiform papillae assessment: A collaborative study among European research units

Fungiform papillae (FP) are the anatomical structures dedicated to gustatory and somatosensory signal triggering. Whether the density of FP (FPD = FP/cm2) is associated with oral responsiveness is controversial, and the disparity in previous findings may be partially due to the diversity in methods used to quantify FP. The present study aims at mapping methods used to estimate FPD and at tentatively assessing the impact of the main procedure variables in FPD estimation. An on-line survey was specifically developed and launched among the European Sensory Science Society members to collect information on methods and procedure variables and to share datasets on FP counting. Seven European research centres responded to the survey. Manual counting was the most popular methodology, and a merged dataset of 1006 observations was obtained. The type of device used for tongue picture acquisition (low-resolution - LR vs high-resolution - HR) was the main procedure variable. FPD mean values were lower when assessed by LR (35.8) than with HR devices (41.5). Distribution of FPD for LR and HR datasets were similar thus comparisons among studies in which different resolution devices have been used are reliable. Picture modifications and data validation did not significantly affect FPD estimation obtained from HR devices, while both these variables significantly affected FPD values collected with LR devices. Both HR and LR procedures were able to capture the differences in FPD due to age and gender. Overall, measures from HR devices appear the best option to depict the inter-individual variability in FPD. Automated procedures appear underutilised.

The gustin gene variation at rs2274333 and PROP taster status affect dietary fat perception: a stepwise multiple regression model study

Gustin, a trophic factor for taste bud development, and its polymorphism at rs2274333 influence taste perception of 6-n-propylthiouracil (PROP) and fungiform papillae (FP) density. The PROP taster status affects dietary fat sensing and body composition. However, there is a paucity of research on the gustin genotype with dietary fat perception, PROP tasting ability, and body mass index (BMI). Thus, taste sensitivity to fat and bitterness was evaluated in 178 healthy individuals. The general labeled magnitude scale was used to determine suprathreshold taste intensity ratings, whereas the alternative forced choice approach was used to estimate the taste-sensing ability. The FP density was assessed by applying blue-colored food dye over the anterior region of the tongue. Restriction fragment length polymorphism was used to detect the genetic polymorphism (rs2274333) in the carbonic anhydrase VI (CA-VI) gene. Fisher's chi-square analysis showed that the CA-VI genotype and allelic frequencies significantly correlated (p<0.001) with the PROP taster status and BMI. Healthy individuals with AA genotypes of the CA-VI polymorphism and PROP super-tasters demonstrated stronger gustatory sensitivity for linoleic acid (LA) with greater FP density in comparison to individuals with AG/GG genotypes and other PROP taster groups. Stepwise forward multiple regression analysis indicates that BMI and PROP taster status significantly influence the LA sensing ability. The suprathreshold intensity rating for LA was also significantly impacted by PROP taster status and CA-VI genotypes, with a variation of 73.3%. Overall, our findings show a relationship between the taste papillae environment and the CA-VI genetic mutation at rs2274333, which influenced the gustatory preference for dietary fat and bitter taste.

Evaluation of taste score and fungiform papillae quantification using digital image analysis in COVID-19 patients with smell and taste dysfunction

Background: The COVID-19 pandemic which is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has created a major global health crisis in recent years. Despite this, there have been few studies that have utilized reliable methods to assess changes in taste and smell perception. Therefore, our study aims at the number of fungiform papillae and objective measures of taste perception relationship among COVID-19 patients with olfactory and gustatory disorders. Materials and Methods: This was a cross-sectional analytical study in which 57 COVID-19 patients were recruited who confirmed the dysfunction of taste and smell. Objective assessment of the sense of taste was evaluated using four different standardized solution preparations, and the scores were given according to the patient's statements. Digitalized quantification of fungiform papillae was counted. The data were analyzed with the Pearson's correlation coefficient using the SPSS version. 23 [Licensed JSSAHER, Mysuru, Karnataka, India], and the level of significance was set at &lt;0.001. Results: In terms of altered or reduced taste and smell, male patients exhibited a higher incidence compared to females. Compared to the sour taste, a substantial number of COVID-19 patients have displayed a notable decrease in their ability to taste sweet, salty, and bitter flavors. However, a statistically significant positive correlation was observed between taste scores and fungiform papillae density (r = 0.518, P &lt; 0.001). Conclusion: Our Study demonstrated that the quantitative evaluation of taste perception and the count of fungiform papillae can serve as important indicators of SARS-CoV-2 infection, and could potentially help in the early detection and treatment of COVID-19 patients, as reduced taste function is a significant marker of the disease.

Associations between Sweet Taste Sensitivity and Polymorphisms (SNPs) in the TAS1R2 and TAS1R3 Genes, Gender, PROP Taster Status, and Density of Fungiform Papillae in a Genetically Homogeneous Sardinian Cohort.

Individual differences in sweet taste sensitivity can affect dietary preferences as well as nutritional status. Despite the lack of consensus, it is believed that sweet taste is impacted by genetic and environmental variables. Here we determined the effect of well-established factors influencing the general taste variability, such as gender and fungiform papillae density, specific genetic variants (SNPs of TAS1R2 and TAS1R3 receptors genes), and non-specific genetic factors (PROP phenotype and genotype), on the threshold and suprathreshold sweet taste sensitivity. Suprathreshold measurements showed that the sweet taste response increased in a dose-dependent manner, and this was related to PROP phenotype, gender, rs35874116 SNP in the TAS1R2 gene, and rs307355 SNP in the TAS1R3 gene. The threshold values and density of fungiform papillae exhibited a strong correlation, and both varied according to PROP phenotype. Our data confirm the role of PROP taste status in the sweet perception related to fungiform papilla density, show a higher sweet sensitivity in females who had lower BMI than males, and demonstrate for the first time the involvement of the rs35874116 SNP of TAS1R2 in the sweet taste sensitivity of normal weight subjects with body mass index (BMI) ranging from 20.2 to 24.8 kg/m2. These results may have an important impact on nutrition and health mostly in subjects with low taste ability for sweets and thus with high vulnerability to developing obesity or metabolic disease.

Exploring the association between oral tactile sensitivity measures and phenotypic markers of oral responsiveness.

This study investigated the individual variability in oral tactile sensitivity considering touch, by means of Von Frey Hair monofilaments (VFH) and spatial resolution, using the grating orientation test (GOT). The relationships of the two measures with 6-n-propylthiouracil (PROP) responsiveness and fungiform papillae density and size were investigated. One hundred and forty-four subjects (48.6% women, aged 18-30) participated in the study. VFH and GOT thresholds were assessed by three-down/one-up staircase method. Responsiveness to 3.2 mM PROP was assessed on the general Labeled Magnitude Scale. Fungiform papillae density (FPD) and size were determined from automated counting. VFH thresholds appeared unsuitable to reveal individual variation in responsiveness to point-pressure on the tongue. The frequency of GOT thresholds approximated a normal distribution and covered the whole range of variation, thus indicating an ability to measure individual variation in oral tactile sensitivity. No significant linear correlations were found between any of the oral tactile sensitivity measures and PROP responsiveness, FPD total and size class. VFH and GOT thresholds were not significantly associated. Agglomerative hierarchical clustering was used to classify participants for their PROP responsiveness, total FPD and GOT threshold. Three clusters were identified, C1 (n=67), Cl2 (n=42), and Cl3 (n=35), differing for PROP responsiveness and FPD only. Results encourage future studies to explore association between GOT and both perception and preference for different food texture. Furthermore, deeper investigation of individual variability in sensitivity to different types of oral tactile stimuli would be helpful to capture differences in tactile sensitivity among the most sensitive individuals.

Consequences of Stapes Surgery on Tongue Morphological Characteristics in Narrow Band Imaging, Gustatory Function and General Sensation: A Prospective Tertiary Center Study

(1) Background: Chorda tympani (CT) manipulation during stapes surgery affects its functions. We hypothesized that this alters tongue morphology and sensory functions. (2) Methods: Patients undergoing stapes surgery were tested 1 day preoperatively, 1 and 6 months postoperatively. Narrow band imaging contact endoscopy (NBI) was used to determine the number of fungiform papillae (Npapillae) and the total score of blood vessel morphology (NBItotal). The taste was tested with taste strips. General sensation was tested with a static two-point discrimination. Tests were performed on ipsilateral and contralateral side of the tongue. (3) Results: 52 otosclerosis patients were included in the study. There was a statistically significant decrease of NBItotal (p = 0.005), Npapillae (p = 0.009), sensation of sweet (p = 0.003), salty (p = 0.035), sour (p = 0.036), and bitter taste (p = 0.013) within the test side during the follow-up. A statistically significant impact on presence of dysgeusia for sweet was found 1 month postoperatively (p &lt; 0.005). Postoperative decrease in two-point discrimination score did not reach a statistical significance (p = 0.056). (4) Conclusions: CT manipulation affects fungiform papillae density, vascular patterns and taste sensation. The general sensation of the tongue is not influenced by CT manipulation.

Automated Classification of 6-n-Propylthiouracil Taster Status with Machine Learning.

Several studies have used taste sensitivity to 6-n-propylthiouracil (PROP) to evaluate interindividual taste variability and its impact on food preferences, nutrition, and health. We used a supervised learning (SL) approach for the automatic identification of the PROP taster categories (super taster (ST); medium taster (MT); and non-taster (NT)) of 84 subjects (aged 18–40 years). Biological features determined from subjects were included for the training system. Results showed that SL enables the automatic identification of objective PROP taster status, with high precision (97%). The biological features were classified in order of importance in facilitating learning and as prediction factors. The ratings of perceived taste intensity for PROP paper disks (50 mM) and PROP solution (3.2 mM), along with fungiform papilla density, were the most important features, and high estimated values pushed toward ST prediction, while low values leaned toward NT prediction. Furthermore, TAS2R38 genotypes were significant features (AVI/AVI, PAV/PAV, and PAV/AVI to classify NTs, STs, and MTs, respectively). These results, in showing that the SL approach enables an automatic, immediate, scalable, and high-precision classification of PROP taster status, suggest that it may represent an objective and reliable tool in taste physiology studies, with applications ranging from basic science and medicine to food sciences.

Longitudinal trajectories and determinants of human fungiform papillae density.

Tongue fungiform papillae contain taste buds crucial for taste and hormone-producing taste receptor cells; therefore, they may be considered as endocrine organs and have important age-associated physiological implications. We examine the cross-sectional and longitudinal trajectories of fungiform papillae density in 1084 participants from the Baltimore Longitudinal Study of Aging using linear regression models and mixed effects models. At baseline, the mean age was 67.86 ± 14.20 years, with a mean follow-up time among those with repeat visits of 4.24 ± 1.70 years. Women (53%) were younger (66.85 ± 13.78 vs. 69.04 ± 14.61 years, p < 0.001) and had a higher fungiform papillae density than men (16.14 ± 9.54 vs. 13.77 ± 8.61 papillae/cm2, p < 0.001). Whites (67%) had a lower fungiform papillae density than non-Whites after adjusting for age and sex. Factors cross-sectionally associated with a lower fungiform papillae density included a higher waist-hip ratio (β = −8.525, p = 0.029), current smoking status (β = −5.133, p = 0.014), and alcohol use within the past 12 months (β = −1.571, p = 0.025). Longitudinally, fungiform papillae density decreased linearly with follow-up time (β = −0.646, p < 0.001). The rate of decline was not affected by sex, race, BMI, waist-hip ratio, smoking, or alcohol use. The longitudinal decline of fungiform papillae density over time needs to be explored further in order to identify other possible age-associated physiological determinants.

Oral physiology, sensory acuity, product experience and personality traits impact consumers’ ability to detect particles in yoghurt

Food texture is a major driver of consumer food acceptance and is influenced by the presence of particles. The objective of this study was to determine if individual differences in human factors (demographic, oral physiology, product experience and psychology) are associated to consumers’ ability to detect particles in semisolid foods (namely yoghurt). A systematic design was employed involving nine yoghurt samples with spherical agar microgels added at levels in the range of human sensory threshold for particle detection in yoghurt. Consumers (n = 117) rated product acceptability, identified specific product sensory properties by Check All That Apply (CATA), and completed a questionnaire including demographics, personality typing, and product related questions. In addition, consumer saliva flow rate, mouth volume, tactile sensitivity, fungiform papillae density, and 6-n-propylthiouracil (PROP) and salt (NaCl) sensitivity were measured. Consumers who identified particles and/or drying in samples (by CATA) had significantly higher fungiform papillae density, were more oral tactile sensitive and were more sensitive to salt taste. The same consumers were more likely to have an open personality type, reported a preference for more cohesive yoghurt textures (fatty, spoonable, not-separated) and were more likely to have a history of consuming yoghurt products in combination with cereal and for preparation of smoothies. These results demonstrate that acceptance and rejection of particles in soft-foods is driven by a combination of intrinsic product factors and human factors. Understanding these drivers will assist the food industry to more accurately target products to specific markets.

Combined influence of TAS2R38 genotype and PROP phenotype on the intensity of basic tastes, astringency and pungency in the Italian taste project

The combined influence of TAS2R38 genotype and PROP phenotype on oral sensations is still to be clarified. The present work investigates their influence on the intensity of basic tastes and somatosensory stimuli (capsaicin, aluminium sulphate), using a large cohort of 1117 individuals. The possible influences of gustin genotype and fungiform papillae density were also assessed. PROP phenotype was mainly associated with TAS2R38 genotype with AVI/AVI individuals reporting the lowest mean bitterness intensity (12.6 ± 1.26), and PAV/AVI individuals rating PROP lower (46.53 ± 0.93) than PAV/PAV individuals (54.14 ± 1.33). However, 25% of AVI/AVI subjects reported PROP bitterness perception higher than ‘moderate’ and small percentages of both PAV/PAV and PAV/AVI responded very little to PROP stimulation. PROP phenotype significantly affected ratings to all the tastant solutions with ST subjects giving the highest ratings and NT the lowest. An unexpected systematic effect of TAS2R38 diplotype on perceived intensity was found, with AVI/AVI individuals rating tastant solution intensity higher than PAV/AVI and PAV/PAV for all the stimuli. Recursive partitioning analysis was used to determine the influence of the explanatory variables (TAS2R38 diplotype, PROP status, age and gender) on intensity for each tastant solution. Regression trees indicated that TAS2R38 genotype is the most important variable for explaining differences in intensity of basic tastes and astringency, when compared to PROP responsiveness, gender, and age. Gender was the primary determinant of heightened perception of pungency. PROP status was the second most influential variable in all the models, with limited influence only on sweetness and umami perception. No significant variations of intensity of taste and somatosensory sensations were found in association to gustin polymorphism or fungiform papillae density. These findings call for a re-examination of the notion that the TAS2R38 gene uniquely controls PROP tasting and for future research devoted to a more in-depth genetic characterization of the AVI/AVI group and its possible associations with other polymorphisms.

A matter of taste: Gustatory sensitivity predicts political ideology.

Previous research has shown that political attitudes are highly heritable, but the proximal physiological mechanisms that shape ideology remain largely unknown. Based on work suggesting possible ideological differences in genes related to low-level sensory processing, we predicted that taste (i.e., gustatory) sensitivity would be associated with political ideology. In 4 studies (combined N = 1,639) we test this hypothesis and find robust support for this association. In Studies 1-3, we find that sensitivity to the chemicals PROP and PTC-2 well established measures of taste sensitivity-are associated with greater political conservatism. In Study 4, we find that fungiform papilla density, a proxy for taste bud density, also predicts greater conservatism, and that this association is partially statistically mediated by disgust sensitivity. This work suggests that low-level physiological differences in sensory processing may shape an individual's political attitudes. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Exploring the relationships between oral sensory physiology and oral processing with mid infrared spectra of saliva

Saliva is a critical component during eating, as it performs an important role in sensory perception and processing of food. However, the individual variations and relationships between oral sensory physiology, oral processing and saliva with food are not well understood. The aim of this study was to analyse as well as to interpret individual variations and relationships between the mid infrared (MIR) spectra of saliva and oral physiology and behaviour (e.g. fungiform papillae, saliva flow, and oral processing time). The fungiform papillae density of the tongue, resting saliva flow rate and oral processing time were measured in participants from a sensory study (n = 52). The MIR spectra of unstimulated saliva samples sourced from participants were collected and used to develop partial least squares (PLS) regression models. These models were utilised to interpret the relationships and individual variations between saliva quantity, oral sensing physiology, and oral processing with the saliva spectra. The coefficient of determination (R2) and the standard error in cross validation (SECV) obtained were for saliva flow rate (R2 0.65–0.83, SECV 0.25–0.31), papillae density of tongue (R2 0.73–0.83, SECV 7.4–11.2), and oral processing time (R2 0.7–0.87, SECV 1.66–3.04). Optimal models were obtained when participants were divided into groups namely young male, young female, and older participants. Different PLS loadings in the MIR fingerprint regions were observed between different groups, which demonstrates that different components of saliva connect with oral sensing physiology and oral processing differences among different demographic groups. These results indicated the potential of the salivary fingerprint spectra to understand the consumer eating experience and food selection more deeply, providing a tool in marketing and sensory experiments.

Individual differences in oral tactile sensitivity and gustatory fatty acid sensitivity and their relationship with fungiform papillae density, mouth behaviour and texture perception of a food model varying in fat

Fat provides multimodal stimulation, particularly through mouthfeel and as a taste stimulant via free fatty acids. Individuals vary in perception of both mouthfeel and taste sensations from fat. Papillae number on the tongue can influence oral tactile and taste sensitivity. In addition, mouth behaviour (how foods are manipulated in the mouth during eating before swallowing) varies between individuals, and may influence mouthfeel perception. Limited research has explored the relationships between these factors.Fatty acid (FA) taste sensitivity was measured at two levels of oleic acid. Oral tactile sensitivity was measured using von Frey filaments. Fungiform papillae density (FPD) was measured on the tongue anterior. Mouth behaviour (MB) was measured by Graphic Jeltema/Beckley Mouth Behaviour (JBMB) classification tool. Mouthfeel perception (hardness, crunchiness, and greasiness) in a biscuit model was measured to examine the influence of FPD, tactile sensitivity and MB on mouthfeel perception.Higher FPD was significantly related to higher taste sensitivity to fatty acid and to higher oral tactile sensitivity. FPD and oral tactile sensitivity both significantly influenced mouthfeel perception of biscuits. The results demonstrate the need to characterise individual differences in oral sensory perception by more than one method, and suggest oral tactile sensitivity can be used as a marker of FPD. Further studies are required to understand the impact of MB on sensory perception. The BMI of participants in this study was negatively related to oral tactile sensitivity and the perception of greasiness.

Effect of cross-cultural differences on thickness, firmness and sweetness sensitivity

Sensitivity of the somatosensory system may be influenced by multiple physiological parameters. Variations in oral physiology can arise from cross-cultural differences which may potentially affect sensory sensitivity. The aim of this case study was to quantify texture and taste sensitivity in Dutch (Caucasian) and Chinese (Asian) adults living in the Netherlands. Eighty-five healthy subjects were recruited including 44 Dutch (Caucasian) adults (29 females, 22.8 ± 2.3 yrs) and 41 Chinese (Asian) adults (30 females, 24.5 ± 2.1 yrs) living in the Netherlands for less than 1 year. Three sets of stimuli were used to quantify sensitivity of thickness (maltodextrin solutions differing in viscosity), firmness (agar gels differing in fracture stress) and sweetness (sucrose solutions differing in concentration). The 2-Alternative Forced Choice (2-AFC) ascending staircase method was used to determine texture and taste sensitivity. Unstimulated and stimulated saliva flow rate, fungiform papillae density (FPD), lingual tactile threshold and PROP taster status were determined and are referred to as physiological and sensory consumer characteristics. No significant differences were observed between Chinese and Dutch adults for thickness (Dutch 2.60 mPas, Chinese 2.19 mPas), firmness (Dutch 10.5 kPa, Chinese 10.3 kPa) and sweetness sensitivity (Dutch 0.012 g/mL, Chinese 0.017 g/mL). No significant differences were observed between Chinese and Dutch adults for saliva flow rate, lingual tactile threshold and PROP taster status. The relationships between the three sensory sensitivities (thickness, firmness, sweetness) and five physiological and sensory consumer characteristics (unstimulated and stimulated saliva flow rate, FPD, lingual tactile threshold, PROP taster status) were analyzed. Only one out of 15 relationships, firmness sensitivity and FPD, was significantly and weakly related suggesting that inter-individual variation in these consumer characteristics is almost unrelated to sensory sensitivity. We conclude that in this case study thickness, firmness and sweetness sensitivities do not differ between Dutch and Chinese adults living in the Netherlands. Saliva flow rate, fungiform papillae density, lingual tactile threshold and PROP taster status do not explain inter-individual variation in sensory sensitivity between these consumers.

Comparison of manual and machine learning image processing approaches to determine fungiform papillae on the tongue

Human taste perception is associated with the papillae on the tongue as they contain a large proportion of chemoreceptors for basic tastes and other chemosensation. Especially the density of fungiform papillae (FP) is considered as an index for responsiveness to oral chemosensory stimuli. The standard procedure for FP counting involves visual identification and manual counting of specific parts of the tongue by trained operators. This is a tedious task and automated image analysis methods are desirable. In this paper a machine learning image processing method based on a convolutional neural network is presented. This automated method was compared with three standard manual FP counting procedures using tongue pictures from 132 subjects. Automated FP counts, within the selected areas and the whole tongue, significantly correlated with the manual counting methods (all ρs ≥ 0.76). When comparing the images for gender and PROP status, the density of FP predicted from automated analysis was in good agreement with data from the manual counting methods, especially in the case of gender. Moreover, the present results reinforce the idea that caution should be applied in considering the relationship between FP density and PROP responsiveness since this relationship can be an oversimplification of the complexity of phenomena arising at the central and peripherical levels. Indeed, no significant correlations were found between FP and PROP bitterness ratings using the automated method for selected areas or the whole tongue. Besides providing estimates of the number of FP, the machine learning approach used a tongue coordinate system that normalizes the size and shape of an individual tongue and generated a heat map of the FP position and normalized area they cover. The present study demonstrated that the machine learning approach could provide similar estimates of FP on the tongue as compared to manual counting methods and provide estimates of more difficult-to-measure parameters, such as the papillae's areas and shape.

The effects of taste sensitivity and repeated taste exposure on children's intake and liking of turnip (Brassica rapa subsp. rapa); a bitter Brassica vegetable

Low consumption of vegetables in children is a concern around the world, hence approaches aimed at increasing intake are highly relevant. Previous studies have shown that repeated taste exposure is an effective strategy to increase vegetable acceptance. However, few studies have examined the effect of repeated taste exposure on children varying in bitter taste sensitivity. This study investigated the influence of taste genotypes and phenotypes on the effects of repeated taste exposure to a Brassica vegetable. 172 preschool children aged 3–5 years were recruited into this study. Turnip was selected as the target vegetable and parents completed a questionnaire to ensure unfamiliarity. During the intervention, children were exposed to steamed-pureed turnip for 10 days (once/day). Intake and liking were measured before, during and after the intervention, and a follow-up was done 3 months post-intervention. Taste genotypes (TAS2R38 and gustin (CA6) genotypes) and taste phenotypes (PROP taster status and fungiform papillae density) were determined. There was a significant effect of exposure shown by significant increases in intake (p < 0.001) and liking (p = 0.008) post-intervention; however, there were no significant effects of taste genotypes or phenotypes on intake and liking. In summary, repeated taste exposure is confirmed to be a good strategy to increase vegetable acceptance in children, regardless of bitter taste sensitivity.