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The primary purpose of this study was to examine whether 2D:4D ratios (a putative measure of prenatal androgen exposure) could be determined using participant-submitted hand images. The secondary purpose was to examine whether 2D:4D ratio was associated with pro-environmental behaviors, attitudes, and empathy, given the recent literature linking sex to environmental attitudes and actions. Participants (The online version contains supplementary material available at 10.1007/s10211-022-00401-5.

Youth carry the burden of a climate crisis not of their making, yet their accumulative lifestyle decisions will help determine the severity of future climate impacts. We surveyed 17–18 year old’s (N = 487) to establish their action stages for nine behaviours that vary in efficacy of greenhouse gas emission (GGE) reduction and the explanatory role of climate change (CC) knowledge, sociodemographic and belief factors. Acceptance of CC and its anthropogenic origins was high. However, the behaviours with the greatest potential for GGE savings (have no children/one less child, no car or first/next car will be electric, eat less meat) have the lowest uptake. Descriptive normative beliefs predicted intent to adopt all high-impact actions, while environmental locus of control, CC scepticism, knowledge of the relative efficacy of actions, religiosity and age were predictive of action stage for several mitigation behaviours (multinomial logistic regression). These findings inform policy and communication interventions that seek to mobilise youth in the global climate crisis response. Supplementary Information The online version contains supplementary material available at 10.1007/s11027-021-09963-4.

Orosensory perception strongly influences food and beverage liking and consumption. Differences between individuals in orosensation present an opportunity to conceptualize and commercialize products based on consumer “taste” responsiveness. The main objective of this study was to examine how the thermal taste phenotype associates with orosensory responsiveness to beer and cider, and more generally to examine differences in and relationships between responsiveness to alcohol-relevant stimuli and to beer/cider. Sixty participants (31 thermal tasters (TTs) and 29 thermal non-tasters (TnTs)) rated the intensity of aqueous solutions of beer- and cider-relevant tastants: iso-α-acid (bitterness), ethanol (irritation, bitterness, sweetness), dextrose (sweetness), and citric acid (sourness) at concentrations typically found in commercial products on generalized labeled magnitude scales (gLMS). Intensity ratings (gLMS) of multiple orosensations elicited by six beer and two cider samples differing in iso-α-acid and ethanol content were also collected. TTs scored the bitterness of ethanol more intensely than did TnTs (p(t)

Thermal taster status (TTS) is determined when the tongue is cooled or warmed, whereby thermal tasters (TT) experience a taste sensation while thermal nontasters (TnT) do not. The literature suggests that TT experience greater responsiveness (higher intensity ratings) to orosensory stimuli; however, small sample sizes and differences in classification schemes between studies confound our understanding of TTS. In addition, up to 50% of individuals (nonclassifiables, NC) have been excluded from previous studies and have yet to be characterized. Raw responses to the thermal-elicitation procedure were used to determine the TTS of the same participants using four published classification schemes, and concordance between the schemes was examined using Fleiss’ kappa. Using a large convenience sample (n = 708), we tested for differences in orosensory (ANOVA) and temperature (Mann-Whitney U) responsiveness between TT, TnT, and NC. TT are more responsive than TnT to both orosensations and temperature changes, regardless of the classification method used despite only moderate concordance between the schemes. Overall, the orosensory and temperature responsiveness of NC is intermediate to that of TT and TnT. However, the responses of NC are not homogeneous and subgroups are identified. The trend of TT being more responsive to orosensory and temperature stimuli is confirmed. The responsiveness patterns of NC subgroups suggest they are misclassified TT and TnT, and can be included in future studies examining thermal tasting. TTS is an important source of individual differences in orosensory responsiveness, and our findings inform best practices for thermal elicitation and classification.

Food choice and habitual diet-related health outcomes are strongly influenced by the oral sensations elicited by food. Of the biological-based mediators of orosensation, thermal tasting—the capacity to experience phantom taste sensations on lingual thermal stimulation—has not been investigated with respect to orosensation and liking of sampled foods. Twenty-three female thermal tasters (TTs) and 21 female thermal non-tasters (TnTs) scored liking of (9-point hedonic scale) and the intensity of orosensations elicited by (gVAS) 22 food and beverage items in duplicate using a randomized complete block design in a customized sensory evaluation laboratory. Foods selected included high fat, high sugar, and high salt items. Sampled items were grouped according to the dominant orosensation(s) elicited (sweet, bitter, sour, salty, astringent, creamy, crunchy, crispy, firm, menthol cool, and grainy), and intensity and liking assessed for each group. No significant differences were found for thermal tasting status (TTS) in intensity ratings of orosensory groupings (p(t) > 0.05). TnTs gave higher liking ratings for creamy foods than TTs (t = 5.99, p = 0.015), and their liking of the “aversive” food grouping was higher than for TTs and approached significance (t = 2.97, p = 0.086). The previously reported variation in orosensation due to TTS observed with simple aqueous solutions, and some beverages may not extend to sampled foods. However, differences in liking are suggested for some food groupings and are worthy of further investigation.

Thermal tasting—the capacity to experience phantom taste sensations on thermal stimulation of the tongue—has been shown to associate with greater responsiveness to orosensations elicited in aqueous solutions and beverages. Here, we sought to determine if this heightened acuity extends to difference thresholds. An ascending two-alternative forced choice method was used to measure difference thresholds for sweetness (sucrose), sourness (tartaric acid), and bitterness (quinine) in a neutral white wine. Individual best-estimate thresholds (BETs) were calculated according to ASTM E-679-04. Group difference thresholds (g/L) for thermal tasters (TT) and thermal non-tasters (TnT), respectively, were sweetness, 3.52 and 5.24; sourness, 0.23 and 0.70; and bitterness, 0.0058 and 0.0060. There was an overall trend of TTs having lower difference thresholds than TnTs, but this was significant only for sourness (t = 3.95, p = 0.002). Additionally, wine expertise was inversely associated with the difference threshold for sweetness (rho = −0.470, p = 0.029) and was a significant source of variation in the analysis of covariance (t = −2.69, t = 0.016). These data provide some preliminary evidence that the supra-threshold intensity “advantage” in orosensory perception previously reported for thermal tasters may extend to difference thresholds and complex products such as wine. These results add to the evidence that thermal tasting represents a potentially important taste phenotype that may associate with food preference and consumption and should also be considered when populating sensory panels.

Introduction There is a continued need for the application of flavour modifiers to improve the sensory profile of products within the functional food market. Additionally, psychophysical studies have tended to confine their scope to stimuli that elicit single sensations, and ingredients that are not always of most interest to the food industry. While basic taste-eliciting compounds and odourants have been used in functional food optimisation, modification can also include the addition of bitter-blocking ingredients. This study examines the impact that these modifiers have both alone and in conjunction with each other on the flavour of (+)-catechin containing model functional beverages.

β-glucosidase is an enzyme important to flavour enhancement. It hydrolyzes glucosides to release aglycones—aroma precursors that are bound to a sugar molecule—thereby making them available to contribute to the flavour of foods and beverages. While there is strong interest within the food and beverage industry to optimizing flavour through the use of exogenous and endogenous glucosidase in production, little is known regarding the possible occurrence of these enzymes within the human oral cavity. This could be an important source of flavour release and/or account for some differences between individuals in flavour perception. In the present study, we determined whether β-glucosidase is present in human saliva. First, an existing spectrophotometric assay that uses p-nitrophenyl-β-O-d-glucopyranoside as a substrate was modified and optimized for use in human saliva. The following variables were evaluated and where necessary, optimized: linearity of the assay signal, possible matrix interference, the effect of heat inactivation of the saliva, absorbance wavelength maxima, substrate saturation concentration, maximum saliva volume and the inclusion of α-cyclodextrin. The modified assay was then used to screen for β-glucosidase activity in the saliva of 20 individuals. Of the 20 samples analyzed, four were tentatively identified as containing active β-glucosidase and were further investigated. Significant differences (p

T2R38 is a bitter taste receptor known to be associated with 6-n-propylthiouracil (PROP) responsiveness, as operationalized by PROP taster status (PTS). Suprathreshold PROP responsiveness is a proxy for general taste responsiveness and has been linked to diet-related behavior and health outcomes, including alcohol consumption, body mass index, and cardiovascular disease risk. The ability to taste PROP allows classification of individuals into three groups: super-tasters (pST), medium-tasters (pMT), or non-tasters (pNT). Recently, another taste phenotype, thermal tasting, has been identified, in which the heating or cooling of a region of one’s tongue evokes a phantom taste response in 20–50 % of individuals. The mechanism behind thermal tasting is not yet known. In this study, we sought to investigate the relationship between TAS2R38 sequence variation with both PROP responsiveness and thermal taster status (TTS). PTS was determined from participants’ intensity rating of a 3.2 mM PROP solution, while TTS was determined based on the presence/absence and intensity (generalized labeled magnitude scale) of oral sensation(s) elicited by temperature changes to a participant’s extended tongue applied by a computer-controlled thermode. Using buccal cell DNA, we performed genotyping of the TAS2R38 variations for 53 individuals, primarily of Caucasian decent. A significant correlation between PTS and three TAS2R38 single nucleotide polymorphisms (SNPs) (rs713598, rs1726866, and rs10246939) was found, as previously reported, with the strongest association seen when all three SNPs were included in the multiple regression model. However, not all PTS differences can be explained by variation at these three SNP sites or other sites in the coding region, suggesting the involvement of additional genes. Although in prior studies both PTS and TTS have been shown to predict general taste responsiveness, our data indicate no association between TTS and the TAS2R38 genotype, suggesting the involvement of different genes in this phenotype. While underpowered due to small sample size, our study was not able to confirm the previously reported association between Gustin SNP rs2274333 genotype and PROP responsiveness. This pilot study provides the first genetic evidence to support previous phenotype-based observation suggesting a lack of association between PROP responsiveness and thermal taster status. Specifically, our data show that TAS2R38 is unlikely to be involved in thermal tasting.

Recently, the phenomenon of thermal taste, where thermal tasters (TTs) perceive taste sensations from the application of thermal stimuli to the tongue, was described. Thermal taster status (TTS) appears to function as a marker of individual variation in orosensory perception, as TTs are more responsive to prototypical orosensory stimuli and flavor attributes in complex beverages than thermal non-tasters. The main objective of this study was to examine the influence of TTS on the relationship between stimulus temperature and orosensory perception. Propylthiouracil (PROP) responsiveness has long been used as an index of individual variation in oral sensation, as general orosensory responsiveness to a variety of stimuli associates with the ability and degree to which individuals perceive PROP's bitterness. PROP taster status (PTS), an expression of individuals' PROP responsiveness, was also examined. Perceptually equi-intense stimuli eliciting sweet, sour, bitter, and astringent sensations were presented at 5 °C and 35 °C and evaluated using time-intensity methodology. Unexpectedly, an apparent trend of TTs reporting higher maximum perceived intensities for all stimuli was not statistically significant, and an examination of individual subjects' data suggests further examination of the influence of TTS on orosensory stimuli is warranted. PROP bitterness and the perceived intensity of orosensory stimuli were not associated at either temperature; however, some differences between PTS groups were found. As previously reported, TTS and PTS interactions were not observed. Interestingly, temperature influenced the maximum intensity perceived from astringent, bitter, and sour stimuli, but not from the sweet stimulus.