Taste Detection Thresholds Research Articles

Towards an understanding of bitterness in white wines: Contribution of 27 compounds assessed by LC-HRMS and sensory analysis

Whereas bitterness perception can modify the taste balance of white wines, its molecular origin remains largely unclear. This work aimed at determining the influence of a selection of the most cited bitter compounds on the bitterness of commercial dry white wines. Forty-two wines were sensorially characterized by a trained panel and divided into two statistically different groups depending on their bitterness. Twenty-seven bitter compounds were selected and five quantitation methods were developed and validated. The methods were used to measure the levels of all the 27 compounds in dry wine, 25 of them in sweet wine and 22 of them in grape juice. The detected concentrations were generally below the taste detection thresholds. No significant positive correlation between the bitterness intensity of the tasted samples and the concentration of the assayed bitter compounds was observed, suggesting the existence of other markers of bitterness in white wines.

Addition of low sodium does not increase sensitivity to glucose in wild-type mice, or lead to partial glucose taste detection in T1R3 knock-out mice

The sodium glucose cotransporter 1 (SGLT1) has been proposed as a non-T1R glucosensor contributing to glucose taste. Studies have shown that the addition of NaCl at very weak concentrations to a glucose stimulus can enhance signaling in the gustatory nerves of mice and significantly lower glucose detection thresholds in humans. Here, we trained mice with (wild-type; WT) and without (knockout; KO) a functioning T1R3 subunit on a two-response operant detection task to differentially respond to the presence or absence of a taste stimulus immediately after sampling. After extensive training (∼40 sessions), KO mice were unable to reliably discriminate 2 M glucose+0.01 M NaCl from 0.01 M NaCl alone, but all WT mice could. We then tested WT mice on a descending array of glucose concentrations (2.0–0.03 M) with the addition of 0.01 M NaCl vs. 0.01 M NaCl alone. The concentration series was then repeated with glucose alone vs. water. We found no psychophysical evidence of a non-T1R taste transduction pathway involved in the detection of glucose. The addition of NaCl to glucose did not lower taste detection thresholds in WT mice, nor did it render the stimulus detectable to KO mice, even at 2 M. The proposed pathway must contribute to functions other than sensory-discriminative detection, at least when tested under these conditions. Detection thresholds were also derived for fructose and found to be 1/3 log10 lower than for glucose, but highly correlated (r = 0.88) between the two sugars, suggesting that sensitivity to these stimuli in this task was based on a similar neural process.

New insights about sensory contribution of grape stems during winemaking: role of astilbin, a sweet polyphenol

In the usual red winemaking process, grapes are destemmed between the harvest and the filling of the vat. However, in regions like Bourgogne, some winemakers let all or a part of the stems in contact with the juice during vatting. This choice will likely affect the sensory properties of wine, such as its gustatory perception. The present study investigated the effect of adding stems during the winemaking process on the concentration of a sweetening compound, astilbin. The sensory contribution of astilbin in wines was first clarified by measuring its taste detection threshold and comparing it with the concentrations found in various commercial wines. Then, experimental wines resulting from the addition of stems in various proportions were analysed. These practical experiments were carried out in various French wine estates, in Bourgogne, Beaujolais and Bordeaux, over three vintages, allowing the comparison of different grape varieties, namely Pinot noir, Gamay and Merlot. For each experiment, the modality with the addition of stems was compared with a vat of destemmed grapes from the same plot. Samples were taken throughout the winemaking process to be analysed by liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-Exactive, Orbitrap analyser). The results showed that the addition of stems during vatting significantly increased astilbin concentration. Furthermore, this increase varied according to the grape variety. Whereas the astilbin contents were lower in Merlot wines than in Pinot noir or Gamay wines, the ratio between its concentration of wines from the two modalities was higher in Merlot than in Pinot noir and Gamay. The localisation of astilbin in the different components of the bunch, depending on the grape variety, was also investigated to understand this difference better. Thus, a higher abundance of astilbin in stems than in skins was found in the Merlot variety, whereas, for Gamay and Pinot noir, the total quantity of astilbin in a bunch was located in equal proportions in stems and skins. These new results bring new tools to understand better the practice of whole bunch vinification from a chemical perspective.

Repeatability of the Measurement of Electrical Taste Detection Thresholds in Healthy Young Females

Repeatability of the Measurement of Electrical Taste Detection Thresholds in Healthy Young Females

Diet quality, nutritional status and taste recognition are impaired in men with substance use disorder.

This study aimed to (1) evaluate the nutritional status, prevalence of malnutrition and dietary habits in individuals using substances and (2) examine the possible effects of substance use on the perception of five basic tastes. Ninety male individuals with substance use disorder (SUD) (heroin = 78, cocaine = 12) and 32 non-users participated in the study conducted at Manisa Alcohol and Substance Addiction Treatment Center (AMATEM), Turkey. To determine the quality of the diet, the mean nutrient adequacy ratio (MAR) was calculated based on 24-h recall food consumption records of the individuals. Subjective Global Assessment (SGA) was employed to determine nutritional status, and anthropometric measurements were also taken from the individuals. The taste detection and recognition thresholds were determined with solutions with different concentrations for bitter, sour, sweet, umami and salty tastes and scored, with higher scores indicating lower thresholds. Mild-moderate malnutrition was determined in 50% of the individuals with SUD based on SGA. The body mass index (BMI) of individuals with SUD was found to be 21.2 ± 1.88 kg/m2 , and 24.1 ± 1.64 kg/m2 for non-users (p < 0.001). Diet quality, evaluated by MAR, was lower in individuals with SUD (54.7 ± 18.9%) than in non-users (93.5 ± 9.0%) (p < 0.001). The taste detection and taste recognition thresholds of individuals with SUD were impaired, and the threshold scores for sour, salty, sweet and umami taste recognition were significantly lower compared with non-users, with the lowest substance user threshold scores observed for the sweet recognition threshold. Standardised nutritional and behavioural interventions designed by dietitians should be provided for drug users in treatment centres and integrated with medical treatment practices.

Paediatric Medicinal Formulation Development: Utilising Human Taste Panels and Incorporating Their Data into Machine Learning Training.

This review paper explores the role of human taste panels and artificial neural networks (ANNs) in taste-masking paediatric drug formulations. Given the ethical, practical, and regulatory challenges of employing children, young adults (18-40) can serve as suitable substitutes due to the similarity in their taste sensitivity. Taste panellists need not be experts in sensory evaluation so long as a reference product is used during evaluation; however, they should be screened for bitterness taste detection thresholds. For a more robust evaluation during the developmental phase, considerations of a scoring system and the calculation of an acceptance value may be beneficial in determining the likelihood of recommending a formulation for further development. On the technological front, artificial neural networks (ANNs) can be exploited in taste-masking optimisation of medicinal formulations as they can model complex relationships between variables and enable predictions not possible previously to optimise product profiles. Machine learning classifiers may therefore tackle the challenge of predicting the bitterness intensity of paediatric formulations. While advancements have been made, further work is needed to identify effective taste-masking techniques for specific drug molecules. Continuous refinement of machine learning algorithms, using human panellist acceptability scores, can aid in enhancing paediatric formulation development and overcoming taste-masking challenges.

Visualization of the relationship between electrogustometry and whole mouth test using multidimensional scaling

Interpreting the relationship between different taste function tests of different stimuli, such as chemical and electrical stimulation, is still poorly understood. This study aims to analyze visually as well as quantitatively how to interpret the relationship of results between taste function tests using different stimuli. Patients who underwent the whole mouth test and Electrogustometry (EGM) at a tertiary medical center between August 2018 and December 2018 were reviewed retrospectively with electronic medical records. Of the 110 patients, a total of 86 adults who self-reported that their taste function was normal through a questionnaire were enrolled. EGM measured the thresholds of the chorda tympani (CT) and glossopharyngeal nerve (GL) area of the tongue. The whole mouth test measured detection and recognition thresholds for sweet, salty, bitter, sour, and umami taste. Statistical analyses of Pearson’s, Spearman’s rank and polyserial correlation and multidimensional scaling (MDS) was performed. The EGM threshold for the average value of both CT regions and the recognition threshold of the whole mouth test were significantly correlated in sweet, salty, bitter, and sour taste (r = 0.244–0.398, P < 0.05), and the detection threshold was correlated only significant in sweet (r = 0.360, P = 0.007). In the MDS analysis results, the three-dimensional (D) solution was chosen over the 2-D solution because of the lower stress. Detection-, recognition threshold of whole mouth test and EGM thresholds of CT and GL area, those were standardized by Z-score, formed well-distinguished sections in the MDS analyses. The EGM threshold of the CT area was closer to the detection and recognition thresholds than the EGM threshold of the GL area. In general, the EGM threshold was closer to the recognition threshold than the detection threshold for each taste. Overall, visualization of the relationship of whole mouth test and EGM by MDS was in good agreement with quantitative analysis. EGM and whole mouth test seem to reflect different aspects of taste. However, when interpreting the EGM results, the EGM threshold of the CT area will show more similarity to the recognition threshold than the detection threshold for the whole mouth test.

Taste Detection Threshold in Relation to Pfizer COVID-19 Vaccine.

Background The first hit of the COVID-19 pandemic was reported in December 2019 in Wuhan, Hubei province, China, and wholesale seafood markets were reported to be the source of infection. The development of effective and safe vaccines against SARS-CoV-2 has been extremely fast. The development of the COVID-19 mRNA vaccine started in early January 2020, after the release of the SARS-CoV-2 genetic sequence by the Chinese Center for Disease Control and Prevention and its global dissemination by the Global Initiative on Sharing All Influenza Data (GISAID). Aim The current study aims to evaluate the taste detection threshold after the second shot of Pfizer COVID-19 vaccination at different intervals and after the booster shot. Materials and methods A multistage sampling technique was used to select all Iraqi healthcare workers (HCWs) to whom the inclusion criteria were applied, from Baghdad Medical City and Al-Yarmouk Teaching Hospital participated in this study. The total number of selected subjects was 85. The ages of HCWs ranged from 24 to 60 years. The first study group (G1) comprised 30 HCWs who received the COVID-19 vaccination from Pfizer in two doses. The subjects were recruited into this group two weeks to three months after being vaccinated and had no history of COVID-19 symptoms. The second group (G2) comprised 30 HCWs who received the COVID-19 vaccination from Pfizer in two doses. They were recruited three to six months after they were vaccinated and had no prior history of the virus' symptoms. The third group (G3) was of 25 HCWs who received a third booster dose of COVID-19 vaccination from Pfizer two weeks afterthe booster dose. The taste detection threshold was performed forfour basic tastes: sweet, sour, salt, and bitter. Results The taste detection threshold for (sweets) showed a significant difference between the first and second groups and the second and third groups. The taste detection threshold of sweets was significantly higher in the second group. Conclusions After three to six months from getting the second dose, the taste detection threshold for sweets was assessed as high. This means that the flavor will be harder to perceive. Pfizer COVID-19 immunization may be assumed to be one of the causes of defected taste sensation to sweet flavor.

A novel study on recently discovered fatty acid taste detection threshold among young lean and overweight individuals

Background: It is likely that the sense of taste evolved to alert humans to the nutritive or poisonous nature of possible foods. This study has been undertaken to unravel and highlight a possible relationship between the fat taste threshold and obesity, especially among young population. Aims and Objectives: The aim of the study was to detect the fat taste threshold in young lean and overweight individuals and to compare the threshold in these individuals with age- and sex-matched normal individuals. Materials and Methods: The taste threshold for fat was detected in 50, normal (Body mass index [BMI] (18.5–24.9 kg/m2), lean (BMI &lt;18.5 kg/m2), and overweight individuals (BMI of 25.0–29.9 kg/m2) of both sexes with the age between 18 and 30 years. The statistical analysis was done using Analysis of variance test. Results: Young lean individuals could detect the fatty acid taste at the lower concentration compared to overweight individuals, who detected at higher concentration (P &lt; 0.01). Conclusion: Lean male and female showed a significant taste detection threshold for fat at low concentration compared to overweight male and female as well as with normal individual. Fatty acid taste detection is very important in day-to-day life for the disease-free life.

The use of herbs and spices in sodium-reduced meals enhances saltiness and is highly accepted by the elderly

Dietary intake of sodium by the elderly population in nursing homes should be monitored due to the greater sensitivity of elderly people to sodium. This study aimed to explore any associations between sodium intake and salt taste perception in an institutionalized elderly population and to research the potential of sodium reduction by the use of herbs and spices. The study included 123 senior citizens in nursing home who were on average 80.7 (±5.8) years old. The nutritionist collected data on sodium intake by using 24-hour recall on two non-consecutive days, and taste perception was assessed by salty taste detection and recognition thresholds. An intervention study of sodium reduction was tested on three categories of dishes, potentially high sources of sodium. The participants were divided into three intervention groups, the control group, the 30 % sodium reduction group, and the 30 % sodium reduction with an added blend of herbs and spices. The elderly's average sodium intake exceeded the recommendation by 70 %. The study determined a significant positive correlation between sodium intake and a higher salt taste threshold (r = 0.17; p < 0.05). The saltiness of sodium-reduced foods was significantly lower than the control, but herbs and spices enhanced the saltiness, and the intensity was the same as the control. The liking for sodium-reduced meals was the same as for the control. A declining salty taste is an important determinant of elderly nursing home residents' adherence to the dietary recommendation for sodium intake. Reducing sodium content in meals through the careful addition of spices and herbs aids elderly people in maintaining healthy dietary habits.

Decoding of the Saltiness Enhancement Taste Peptides from the Yeast Extract and Molecular Docking to the Taste Receptor T1R1/T1R3.

The development of saltiness or saltiness enhancement peptides is important to decrease the dietary risk factor of high sodium. Taste peptides in the yeast extract were separated by ultrafiltration and subsequently identified by UPLC-Q-TOF-MS/MS. The 377 identified peptides were placed into the umami receptor T1R1/T1R3. The results showed that eight taste peptides with higher binding energies were screened by molecular virtual docking, and the results revealed that Asp218, Ser276, and Asn150 of T1R1 play key roles in umami docking of peptides. The taste characteristic description and saltiness enhancement effect results suggested that PKLLLLPKP (sourness and umami, 0.18 mM), GGISTGNLN (sourness, 0.59 mM), LVKGGLIP (umami, 0.28 mM), and SSAVK (umami, 0.35 mM) had higher saltiness enhancement effects. The sigmoid curve analysis further confirmed that the taste detection threshold of the GGISTGNLN in the peptide and salt model (157.47 mg/L) was lower than 320.99 mg/L and exhibited a synergistic effect on saltiness perception, whereas SSAVK, PKLLLLPKP, and LVKGGLIP exhibited additive effects on the saltiness perception. This work also corroborated previous research, which indicated that the sourness and umami taste attributes could enhance the saltiness perception.

Detection of Bitterness in Vitamins Is Mediated by the Activation of Bitter Taste Receptors.

Vitamins are known to generate bitterness, which may contribute to an off-taste or aftertaste for some nutritional supplements. This negative sensation can lead to a reduction in their consumption. Little is known about the bitter taste threshold and taste sensing system for the bitter taste detection of vitamins. To better understand the mechanisms involved in bitterness perception, we combined taste receptor functional assays and sensory analysis. In humans, bitter taste detection is mediated by 25 G-protein-coupled receptors belonging to the TAS2R family. First, we studied the bitterness of thirteen vitamins using a cellular-based functional taste receptor assay. We found four vitamins that can stimulate one or more TAS2Rs. For each positive molecule–receptor combination, we tested seven increasing concentrations to determine the half-maximal effective concentration (EC50) and the cellular bitter taste threshold. Second, we measured the bitter taste detection threshold for four vitamins that exhibit a strong bitter taste using a combination of ascending series and sensory difference tests. A combination of sensory and biological data can provide useful results that explain the perception of vitamin bitterness and its real contribution to the off-taste of nutritional supplements.

Correlates of bitter, sweet, salty and umami taste sensitivity in European children: Role of sex, age and weight status - The IDEFICS study

We aimed to describe differences in taste sensitivity in children according to age across 7- to 11-year-old children from eight European countries. We further compared taste sensitivity between boys vs. girls and under-/normal weight vs. overweight/obese children. Within the European multicentre IDEFICS (Identification and prevention of dietary and lifestyle-induced health effects in children and infants) study, 1938 school children participated in sweet, bitter, salty and umami detection threshold tests between 2007 and 2010, using the paired comparison staircase method. The lowest concentration at which the child was able to detect a difference to water was determined as taste detection threshold as a proxy of taste sensitivity. Mean taste thresholds were calculated stratified for sex, age groups, weight groups and country. BMI was calculated using measured height and weight; socio-demographic information was collected using questionnaires. Ordinal logistic regressions were conducted to investigate the association between sex, weight status (as categorical exposure variable) and age (as continuous exposure variable) and the taste sensitivity for the four taste modalities (as outcome), separately. Older children were more taste sensitive for sweet and salty and less taste sensitive for umami and bitter than younger children. Girls were more sensitive to sweet taste than boys. Overweight or obese children were less sensitive to sweet and salty taste compared to normal weight children This was the first study comparing taste sensitivity by measuring taste thresholds in children across different European countries. We conclude that taste thresholds are associated with weight status, children become more sensitive to sweet and salty tastes with increasing age, and girls might be more sensitive to sweet than boys.

Potential Effects of Prolonged Water-Only Fasting Followed by a Whole-Plant-Food Diet on Salty and Sweet Taste Sensitivity and Perceived Intensity, Food Liking, and Dietary Intake.

The overconsumption of calorie-dense foods high in added salt, sugar, and fat is a major contributor to current rates of obesity, and methods to reduce consumption are needed. Prolonged water-only fasting followed by an exclusively whole-plant-food diet free of added salt, oil, and sugar may reduce the consumption of these hyper-palatable foods, but such effects have not been quantified. Therefore, we conducted a preliminary study to estimate the effects of this intervention on salty and sweet taste detection and recognition thresholds and perceived taste intensity after at least five days of fasting and at refeed day three. We also assessed the effects on sweet, salty, and fatty food preference and overall dietary consumption 30 days after the day three refeed visit. Based on this data, we estimated that 10 days after the start of the fasting, salty taste recognition, sweet taste detection, and sweet taste recognition thresholds decreased significantly, salty taste intensity ratings increased significantly, and sweet taste intensity ratings decreased significantly. We also have preliminary data that prolonged water-only fasting followed by refeeding on an exclusively whole-food-plant diet may reduce salty/fatty and sweet/fatty food liking, reduce sugar intake, and increase vegetable intake. These results support further research into the effects of fasting and diet on taste function and food likability and consumption.

The Influence of Roux-en-Y Gastric Bypass and Diet on NaCl and Sucrose Taste Detection Thresholds and Number of Circumvallate and Fungiform Taste Buds in Female Rats.

Roux-en-Y gastric bypass (RYGB) in rats attenuates preference for, and intake of, sugar solutions. Additionally, maintenance on a high-fat diet (HFD) reportedly alters behavioral responsiveness to sucrose in rodents in short-term drinking tests. Due to the fact that the behavioral tests to date rely on the hedonic value of the stimulus to drive responsiveness, we sought to determine whether taste detection thresholds to sucrose and NaCl are affected by these manipulations as measured in an operant two-response signal detection paradigm. Female rats were maintained on HFD or chow for 10 weeks, at which point animals received either RYGB or SHAM surgery followed by a gel-based diet and then powdered chow. Upon recovery, half of the rats that were previously on HFD were switched permanently to chow, and the other rats were maintained on their presurgical diets (n = 5–9/diet condition × surgery group for behavioral testing). The rats were then trained and tested in a gustometer. There was a significant interaction between diet condition and surgery on NaCl threshold that was attributable to a lower value in RYGB vs. SHAM rats in the HFD condition, but this failed to survive a Bonferroni correction. Importantly, there were no effects of diet condition or surgery on sucrose thresholds. Additionally, although recent evidence suggests that maintenance on HFD alters taste bud number in the circumvallate papillae (CV) of mice, in a subset of rats, we did not find that diet significantly influenced taste pores in the anterior tongue or CV of female rats. These results suggest that any changes in sucrose responsiveness in intake/preference or hedonically oriented tests in rats as a function of HFD maintenance or RYGB are not attributable to alterations in taste sensitivity.

Influence of fresh pineapple intake on human taste detection and recognition thresholds of basic taste stimulants

AbstractThis study aims to determine the effects of different pineapple maturity indices on the human taste and recognition threshold. Sensitivity levels of the subject's taste buds on four basic tastes, sweet, salty, sour, and bitter, were observed before, after they had ingested 50 g and up to 100 g of pineapple at maturity indices 3–7. Consumption of pineapple as low as 50 g had a significant (p &lt; .02) influence on the sweet and bitter taste thresholds. The sensitivity of sweetness decreased (p &lt; .02) after 50 g of pineapple intake at all maturation indices. However, the sensitivity of bitter taste was enhanced significantly after pineapple intake of 50 g at maturation indices 3 and 4. Pineapple intake at lower maturity indices had significantly influenced sweet and bitter taste thresholds that could impact food perception.Practical ApplicationsThe manuscript brings a contribution to the field of food sensory evaluation and consumer studies. It reveals that while enjoying eating fresh pineapple, bromelain may affect taste receptors, influencing taste sensitivity, which could be a factor in determining food quality. The finding could be used as a guideline for exclusion criteria for the panelist selection or screening involved in the sensory evaluation.

Comparing Taste Detection Thresholds across Individuals Following Vegan, Vegetarian, or Omnivore Diets.

Taste perception plays an undisputed role in food choice, preference, and intake. Recent literature suggests that individual diet and taste sensitivity may have a reciprocal relationship, with evidence highlighting that specific diets can alter taste sensitivities. Commensurate with an increase in the prevalence of plant-based diets is the importance of investigating if following a vegetarian or vegan diet is associated with altered taste sensitivities. In this study, the taste detection thresholds for six compounds (i.e., sweet—sucrose, salty—sodium chloride, sour—citric acid, umami—monosodium glutamate, MSG, bitter—caffeine, and metallic—iron II sulphate heptahydrate) were measured for a total of 80 healthy, New Zealand European females aged 18–45 years old, who were categorised as 22 vegans, 23 vegetarians, and 35 omnivores. Each participant’s detection thresholds to these compounds were measured across two sessions, using an ascending Method of Limits with two-alternative-forced-choice presentations. The threshold data were analysed using both multivariate (i.e., principal component analysis) and univariate (i.e., ANCOVA) techniques to assess differences across the three types of diet. Multivariate analysis suggested that the omnivore group had distinct taste sensitivity patterns across the six compounds compared to the vegetarian or vegan group, which were characterised by relatively heightened sensitivity to metallic and lowered sensitivity to sweetness. Furthermore, the vegetarian group was shown to have a significantly lower detection threshold to bitterness (i.e., caffeine) relative to the other two groups (p < 0.001). While future study is required to investigate the cause–effect relationship between individual diet and taste sensitivities, the present study provides a systematic evaluation of taste sensitivities of individuals following distinct diets. This information may be valuable to future gustatory research as well as to food manufacturers.

Psychophysical Tracking Method to Assess Taste Detection Thresholds in Children, Adolescents, and Adults: The Taste Detection Threshold (TDT) Test

This paper describes a two-alternative, forced-choice, staircase, tracking procedure, called the Taste Detection Threshold (TDT) test, that provides a reliable measure of sweet, salty, and umami taste detection thresholds from childhood to adulthood. Advantages of the method include procedures that are identical for children and adults, thus allowing the determination of age-related and individual differences in taste perception, if any, and tasks that can be completed in a relatively short time frame, do not rely on continuous attention or require memorization, control for subjective response biases, and minimize the impact of language development. After a 1 hour fast, participants are presented with pairs of solutions; in each pair, one solution is water, and the other solution contains varying concentrations of the tastant. Using a whole-mouth tasting method, participants taste each solution (without swallowing and with rinsing between tastings) and then point to the solution with a taste or that tastes different from water. The concentration of the stimulus in the subsequent pair increases after a single incorrect response and decreases after two consecutive correct responses. A reversal occurs when the concentration sequence changes direction. The task is deemed completed after the occurrence of four reversals, provided there are a maximum of two dilution steps between two successive reversals, and the series of reversals do not form an ascending pattern. These additional criteria ensure greater reliability in outcomes. The TDT is then calculated as the geometric mean of the concentrations of the four reversals. This method has real-world relevance as it provides information on a dimension of taste perception that is independent of hedonics, and that can change with aging and certain disease states, making it a valuable psychophysical test.

Psychophysical Tracking Method to Assess Taste Detection Thresholds in Children, Adolescents, and Adults: The Taste Detection Threshold (TDT) Test

This paper describes a two-alternative, forced-choice, staircase, tracking procedure, called the Taste Detection Threshold (TDT) test, that provides a reliable measure of sweet, salty, and umami taste detection thresholds from childhood to adulthood. Advantages of the method include procedures that are identical for children and adults, thus allowing the determination of age-related and individual differences in taste perception, if any, and tasks that can be completed in a relatively short time frame, do not rely on continuous attention or require memorization, control for subjective response biases, and minimize the impact of language development. After a 1 hour fast, participants are presented with pairs of solutions; in each pair, one solution is water, and the other solution contains varying concentrations of the tastant. Using a whole-mouth tasting method, participants taste each solution (without swallowing and with rinsing between tastings) and then point to the solution with a taste or that tastes different from water. The concentration of the stimulus in the subsequent pair increases after a single incorrect response and decreases after two consecutive correct responses. A reversal occurs when the concentration sequence changes direction. The task is deemed completed after the occurrence of four reversals, provided there are a maximum of two dilution steps between two successive reversals, and the series of reversals do not form an ascending pattern. These additional criteria ensure greater reliability in outcomes. The TDT is then calculated as the geometric mean of the concentrations of the four reversals. This method has real-world relevance as it provides information on a dimension of taste perception that is independent of hedonics, and that can change with aging and certain disease states, making it a valuable psychophysical test.

Taste detection threshold of human (Homo sapiens) subjects and taste preference threshold of black-handed spider monkeys (Ateles geoffroyi) for the sugar substitute isomalt

The artificial sweetener isomalt is widely used due to its low caloric, non-diabetogenic and non-cariogenic properties. Although the sweetening potency of isomalt has been reported to be lower than that of sucrose, no data on the sensitivity of humans for this polyol are available. Using an up-down, two-alternative forced choice staircase procedure we therefore determined taste detection thresholds for isomalt in human subjects (n = 10; five females and five males) and compared them to taste preference thresholds, determined using a two-bottle preference test of short duration, in a highly frugivorous nonhuman primate, the spider monkey (n = 4; one female, three males). We found that both species detected concentrations of isomalt as low as 20 mM. Both humans and spider monkeys are less sensitive to isomalt than to sucrose, which is consistent with the notion of the former being a low-potency sweetener. The spider monkeys clearly preferred all suprathreshold concentrations tested over water, suggesting that, similar to humans, they perceive isomalt as having a purely sweet taste that is indistinguishable from that of sucrose. As isomalt, like most sweet-tasting polyols, may elicit gastric distress when consumed in large quantities, the present findings may contribute to the choice of appropriate amounts and concentrations of this sweetener when it is employed as a sugar substitute or food additive for human consumption. Similarly, the taste preference threshold values of spider monkeys for isomalt reported here may be useful for determining how much of it should be used when it is employed as a low-caloric sweetener for frugivorous primates kept on a vegetable-based diet, or when medication needs to be administered orally.