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Results for “Taste Threshold”

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PubMed2005

Associations between phenylthiocarbamide gene polymorphisms and cigarette smoking.

Phenotypic evidence indicates that the ability to taste the bitter compounds phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP) may protect against cigarette smoking. In this study, PTC gene haplotypes were found to be associated with both the odds of being a smoker and the importance of cigarette taste as a smoking motive. Smokers (n = 384) and nonsmokers (n = 183) were genotyped for polymorphisms that affect taste sensitivity to PTC and PROP. The "taster" PAV haplotype, relative to the "nontaster" AVI haplotype, was predicted to be associated with reduced odds of being a smoker and lower taste motivation as measured by the Wisconsin Inventory of Smoking Dependence Motives-68 taste/sensory processes scale. The results did not support the predicted association between the PAV and AVI haplotypes and smoker odds, but the AAV haplotype, which confers intermediate PTC/PROP taste sensitivity, was associated with reduced smoker prevalence (49% vs. 70%), chi(2)(1, N = 567) = 10.392, p = .001. The predicted relationship between PAV and AVI and taste motivation was found, F(2, 348) = 3.303, p = .038. The results encourage further exploration of the role of taste/sensory processes in tobacco dependence.

Adult↗
PubMed2005

Ethanol modulates the VR-1 variant amiloride-insensitive salt taste receptor. II. Effect on chorda tympani salt responses.

The effect of ethanol on the amiloride- and benzamil (Bz)-insensitive salt taste receptor was investigated by direct measurement of intracellular Na(+) activity ([Na(+)](i)) using fluorescence imaging in polarized fungiform taste receptor cells (TRCs) and by chorda tympani (CT) taste nerve recordings. CT responses to KCl and NaCl were recorded in Sprague-Dawley rats, and in wild-type (WT) and vanilloid receptor-1 (VR-1) knockout mice (KO). CT responses were monitored in the presence of Bz, a specific blocker of the epithelial Na(+) channel (ENaC). CT responses were also recorded in the presence of agonists (resiniferatoxin and elevated temperature) and antagonists (capsazepine and SB-366791) of VR-1 that similarly modulate the Bz-insensitive VR-1 variant salt taste receptor. In the absence of mineral salts, ethanol induced a transient decrease in TRC volume and elicited only transient phasic CT responses. In the presence of mineral salts, ethanol increased the apical cation flux in TRCs without a change in volume, increased transepithelial electrical resistance across the tongue, and elicited CT responses that were similar to salt responses, consisting of both a phasic component and a sustained tonic component. At concentrations <50%, ethanol enhanced responses to KCl and NaCl, while at ethanol concentrations >50%, those CT responses were inhibited. Resiniferatoxin and elevated temperature increased the sensitivity of the CT response to ethanol in salt-containing media, and SB-366791 inhibited the effect of ethanol, resiniferatoxin, and elevated temperature on the CT responses to mineral salts. VR-1 KO mice demonstrated no Bz-insensitive CT response to NaCl and no sensitivity to ethanol. We conclude that ethanol increases salt taste sensitivity by its direct action on the Bz-insensitive VR-1 variant salt taste receptor.

Algorithms↗
PubMedDate not supplied

Sugar preferences and xylose metabolism of a mammal pollinator, the Namaqua rock mouse (Aethomys namaquensis).

The sugar preferences of 10 Namaqua rock mice, Aethomys namaquensis, were assessed using pairwise combinations of 30% (w/w) solutions of sucrose, glucose, fructose, xylose, and a mixture of equal parts of glucose and fructose. The tests were designed to control for side biases that were apparent in preliminary experiments. The mice preferred sucrose to fructose and glucose. Xylose, although the least preferred sugar, was willingly consumed by the rodents (up to 5.8 mL in 24 h). This contrasts with the strong rejection of xylose by nectarivorous birds on which similar preference tests were performed. The efficiency of xylose absorption and metabolism by A. namaquensis was investigated by measuring dietary intake, blood xylose levels, and urinary and fecal xylose output. Again in contrast to the birds, the apparent absorption efficiency of xylose was found to be very high at 97%, but exactly how the xylose is metabolized requires further study. Xylose is thought to be only slowly metabolized by mammals, and it is possible that intestinal bacteria may serve this purpose, like the ruminal bacteria that break down xylans in plant tissue.

Animals↗
PubMed1976

Zinc nutrition in celiac sprue.

Zinc nutritional status was examined in 10 adult patients with biopsy-proven celiac disease; five of these patients were clinically well on gluten-free diets at the time of study. Plasma zinc and taste acuity were used as indices of zinc nutrition. Depression of plasma zinc and lowered taste discrimination were observed among the untreated patients, and some patients who were otherwise in clinical remission also had impaired zinc nutrition. With confirmation of plasma copper depression in patients with celiac sprue, these observations indicate that trace metal deficiency is another common nutritional complication of adult celiac disease.

Adult↗
PubMed1980

Vitamin A and zinc metabolism in alcoholism.

Vitamin A and zinc metabolism are affected both by ethanol and by hepatic cirrhosis. Ethanol causes abnormal dark adaptation by acting as a competitive inhibitor with retinol for alcohol dehydrogenase in the eye. In animals oral ethanol intake results in increased losses of zinc by the urinary and fecal routes. Vitamin A malnutrition in cirrhotics may be caused by poor diet, malabsorption, decreased hepatic vitamin A uptake, and decreased hepatic storage capacity for vitamin A. In some cirrhotic patients zinc deficiency and or protein deficiency may limit the ability to respond to vitamin A. Combined vitamin A and zinc deficiencies are common in cirrhotics and either may result in abnormal dark adaptation or impaired taste and smell. The interaction of these two micro-nutrients must be kept in mind by the clinician caring for alcoholic or alcoholic cirrhotic patients.

Alcoholism↗
PubMed1985

Gustation as a determinant of ingestion: methodological issues.

To better characterize the relationship between taste function and dietary intake, measures of taste sensitivity, perceived intensity and preference for sweet (sucrose) and bitter (urea) stimuli were assessed in 35 healthy adults using aqueous and food tastants. Observations were then correlated with the proportions of calories contributed by carbohydrate, protein, fat and foods characterized by subjects as predominantly sweet or bitter on 7-day diet records. No significant association was noted among single measures of taste function and any of the five intake parameters, although taste profiles comprised of multiple taste ratings accounted for approximately a third of the variance in sweet and bitter calorie consumption. Levels of nutrient intake could not be predicted at better than chance levels using taste responses. Taste function plays a subordinate role to other determinants of food and nutrient intake, although taste profiles may facilitate the prediction of preferred tastes of diets.

Adolescent↗
PubMed1994

Hydrolysis of sucrose octa-acetate: qualitative differences in taster and demistaster avoidance phenotypes.

Calcium hydroxide and sodium hydroxide were used to hydrolyse sucrose octa-acetate (SOA) as a means of evaluating the taster (Soaa) and demitaster (Soac) allelic phenotypes of the genetic locus Soa. The SWR/J (taster) inbred strain and the B6.SW Soaa (taster) congenic strain were demonstrated to cease avoiding upon nearly complete hydrolysis of 10(-5) M SOA with calcium hydroxide or sodium hydroxide and of 10(-4) M SOA with calcium hydroxide. The BALB/cByJ, C3HeB/FeJ and DBA/2J (demitaster) inbred strains were demonstrated to cease avoiding after only a partial hydrolysis of 10(-3) M SOA using calcium hydroxide. It is suggested that specificity for the number or placement of the acetates of SOA underlies the difference between the taster and demitaster phenotypes.

Animals↗
PubMed1995

Prediction of sweetness intensity for equiratio aspartame/sucrose mixtures.

The Equiratio Mixture Model predicts the responses to a series of equiratio mixtures on the basis of the psychophysical functions for the unmixed components. The model predicts the sweetness of mixtures of sugars and sugar-alcohols successfully, but is unable to predict mixture intensity for substances with different dynamic ranges. In this paper, the equi-intensity concept is introduced in the Equiratio Mixture Model by transforming the physical concentrations expressed in molarity into units that produce approximately equi-intense sensations. An empirical test using aspartame/sucrose mixtures shows that the modified Equiratio Mixture Model yields good predictions of mixture intensities.

Adult↗
PubMed1995

Regional taste sensitivity to NaCl: relationship to subject age, tongue locus and area of stimulation.

Using a signal detection procedure and a microprocessor-controlled gustometer, sensitivity to three concentrations of NaCl (0.01, 0.1 and 1.0 M) was measured on the tongue tip, and on a region 3.0 cm posterior to the tongue tip in 12 young (20-29 years of age) and 12 elderly (70-79 years of age) subjects. Stimulus duration was 2 s; the sizes of the tongue areas stimulated were 12.5, 25 and 50 mm2. On average, the young subjects were more sensitive to NaCl on the tongue tip than on the more posterior stimulation site and exhibited, at both tongue loci, an increase in detection performance as stimulus concentration increased. The elderly subjects, on the other hand, performed at chance level at both tongue loci for all three stimulus sizes and concentrations tested. No sex differences were observed. In the young subjects, the mean R-index increased monotonically as a function of stimulus size for the two highest NaCl concentrations at both tongue loci. A hyperbolic function provided the best fit to these data at the tongue tip, and an exponential function at the more posterior tongue region, implying a different pattern of spatial summation at these two sites. Overall, this study demonstrates that marked age-related changes in regional taste sensitivity to NaCl are present in elderly persons.

Adult↗
PubMed1995

A novel psychophysical procedure for bitter taste assessment in rats.

A persistent problem with attempts to examine bitter taste mechanisms has been the lack of adequate behavioral methodology providing data which parallels that obtained from physiological investigations. We developed a brief contact procedure to assess the ability of rats to detect the presence of a weak bitter compound dissolved in a strong sucrose solution. Male Fischer 344 rats were trained to drink immediately to multiple 10-s presentations of acetaminophen (2, 8, 32, 128 mM), chlorpheniramine maleate (1, 3, 9, 27 mM) L-tryptophan (13.5, 27, 54, 108 mM), pseudoephedrine hydrochloride (1, 4, 16, 64 mM) and quinine hydrochloride (0.008, 0.04, 0.2, 1.0 mM) dissolved in 0.8 M sucrose. The number of licks to sucrose and water were also measured. A microcomputer controlled stimulus presentations and measured the animal's licks of each solution during each 10-s presentation. The responses to the bitter+sucrose mixture were significantly decreased at most concentrations with increasing levels of the bitter component. This was true for all five bitter-tasting compounds, but over different concentration ranges relatively unique to each compound. The present study is the first to characterize the sensory effects of acetaminophen, pseudoephedrine, and chlorpheniramine maleate, all purported to taste bitter to humans. These results demonstrate rats' acute ability to discriminate by taste not only the presence but the concentration of a dilute bitter compound dissolved in a strong sucrose solution.

Acetaminophen↗
PubMed1996

An Equiratio Mixture Model for non-additive components: a case study for aspartame/acesulfame-K mixtures.

The Equiratio Mixture Model predicts the psychophysical function for an equiratio mixture type on the basis of the psychophysical functions for the unmixed components. The model reliably estimates the sweetness of mixtures of sugars and sugar-alcohols, but is unable to predict intensity for aspartame/sucrose mixtures. In this paper, the sweetness of aspartame/acesulfame-K mixtures in aqueous and acidic solutions is investigated. These two intensive sweeteners probably do not comply with the model's original assumption of sensory dependency among components. However, they reveal how the Equiratio Mixture Model could be modified to describe and predict mixture functions for non-additive substances. To predict equiratio functions for all similar tasting substances, a new Equiratio Mixture Model should yield accurate predictions for components eliciting similar intensities at widely differing concentration levels, and for substances exhibiting hypo- or hyperadditivity. In addition, it should be able to correct violations of Stevens's power law. These three problems are resolved in a model that uses equi-intense units as the measure of physical concentration. An interaction index in the formula for the constant accounts for the degree of interaction between mixture components. Deviations from the power law are corrected by a nonlinear response output transformation, assuming a two-stage model of psychophysical judgment.

Adolescent↗
PubMed1996

Recalling taste intensities in sweetened and salted liquids.

The effect of training on recalling taste intensities over 6 weeks was studied using an ad libitum mixing procedure. Subjects tasted sweet and salty standards labeled as "weak' and "strong' (3 and 8% sucrose in redcurrant juice; 0.4 and 1.2% NaCl in beef broth). They subsequently mixed unsweetened and sweetened juice, and unsalted and salted broth, to produce taste intensities that corresponded to the standards. A minimum training (MT) group (n = 13) produced comparison stimuli by tasting and directly comparing with standards in one session only; an extensive training (ET) group (n = 13) did this in six sessions before producing comparison stimuli based on memory only at 1 h, 1 day, 1 week and 6 weeks. An upward bias (chemically determined concentrations of comparison stimuli exceeding those of standards) occurred at 1 day or 1 week in MT subjects for 'weak' and 'strong' sweetness, and for 'strong' saltiness, and sustained thereafter. The upward tendency was also observed in ET subjects but was significant only for 'strong' sweetness. It is important to recognize memory effects such as the one described, as they affect food perceptions and can be a major source of bias in sensory food research.

Adult↗
PubMed1996

Taste responses to binary mixtures of amino acids in the sea catfish, Arius felis.

In vivo electrophysiological recordings in the sea catfish, Arius felis, showed that the magnitude of the integrated facial taste responses to binary mixtures of amino acids was predictable with knowledge obtained from previous cross-adaptation studies of the relative independence of the respective binding sites of the component stimuli. Each component from which equal aliquots were drawn to form the mixtures was adjusted in concentration to provide for approximately equal response magnitudes. The magnitude of the taste responses to binary mixtures whose component amino acids showed minimal cross-adaptation was significantly greater than that to binary mixtures whose components exhibited considerable cross-reactivity. There was no evidence for mixture suppression. The relative magnitude of the taste responses in the sea catfish to stimulus mixtures is similar to that previously reported for olfactory receptor responses in the freshwater channel catfish and chorda tympani taste responses in the hamster.

Amino Acids↗
PubMed1996

Changes in taste perception following mental or physical stress.

Taste perception depends not only on the chemical and physical properties of tastants, but may also depend on the physiological and psychological conditions of those who do the tasting. In this study, the effects of mood state on taste sensitivity was evaluated in humans who were exposed to conditions of mental or physical fatigue and tension. Taste responses to quinine sulfate (bitter), citric acid (sour) and sucrose (sweet) were tested. The intensity of the taste sensations were recorded by a computerized time-intensity (Tl) on-line system. Subjects performed mental tasks by personal computer or physical tasks by ergometer for 10-40 min. Before and after these sessions, the duration of the after-taste and the intensity of the sensation of taste were recorded by the Tl system, and in addition, psychological mood states were evaluated with POMS (Profile of Mood State). Tl evaluation showed that after the mental tasks, the perceived duration of bitter, sour and sweet taste sensations was shortened relative to the control. Total amount of bitterness, sourness and sweetness was also significantly reduced. Furthermore, the maximum intensity of bitterness was significantly reduced. There were no significant differences in bitterness and sweetness sensations following physical tasks. However, relative to before the physical task, the duration of the after-taste of sourness was significantly shortened by the physical task. After the physical task, the buffering capacity of saliva was significantly increased. Thus mental and physical tasks alter taste perception in different ways; the mechanisms underlying these changes remain to be determined.

Adult↗