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At least 865 records · Page 48Linked to original sources
PubMed1988

Quality-specific taste impairment following the application of chlorhexidine digluconate mouthrinses.

Although chlorhexidine has been widely used in the prevention and treatment of gingivitis, its effects on taste sensation have not been well studied. The purpose of the present study was to evaluate taste alterations following regular applications of 0.2% chlorhexidine mouthrinses. 24 healthy and non-smoking clinical instructors, dental assistants and dental students were divided into 3 groups after having reached a status of clinical gingival health by 4 weeks of supervised oral hygiene procedures. Following this, they were asked to abolish all mechanical oral hygiene for a period of 14 days, during which time they rinsed twice daily with different mouthrinses. Group A rinsed with a 0.2% chlorhexidine solution, group B served as control and utilized a 0.001 molar solution of quinine hydrochloride as a placebo rinse. A second control group (C) rinsed with distilled water. At days -3 and -2, as well as at days 1, 2, 13 and 14 of the experimental period, and 1 and 2 days after cessation of the rinsing, taste sensitivity was evaluated by a magnitude estimation, suprathreshold scaling procedure for the 4 taste qualities--sweet, salty, sour and bitter. 6 different concentrations of each of sucrose, sodium chloride, citric acid and quinine hydrochloride were utilized. Magnitude estimations of the perceived intensities of each series of test solutions were calculated. The analysis of co-variance revealed significant differences at the short-term and treatment-related suprathreshold scaling responses between both control groups (B, C) and the test group (A) for the sodium chloride magnitude estimation function. However, no significant inter-group differences in the magnitude estimation function were found for the remaining taste qualities.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1998

PROP (6-n-propylthiouracil) supertasters and the saltiness of NaCl.

Taste blindness to phenylthiocarbamide (PTC) and its chemical relative 6-n-propylthiouracil (PROP) was discovered in the 1930s. Family studies showed that those who could not taste PTC/PROP (nontasters) carried two recessive alleles. In recent years, we have classified tasters into two groups: medium (PROP is moderately bitter) and supertasters (PROP is intensely bitter). With our classification, approximately 25% of Americans are nontasters, 50%, medium tasters, and 25%, supertasters. Studies showed that supertasters form a cohesive group. Anatomical studies showed that supertasters have the most fungiform papillae. Psychophysical studies showed that supertasters perceive the most intense bitterness and sweetness from a variety of compounds, the most intense burn from oral irritants, and the most intense tactile sensations from viscous solutions. Oral burn and touch are presumably perceived to be the most intense to supertasters because taste buds in fungiform papillae are innervated by the trigeminal nerve (pain, touch) as well as the chorda tympani nerve (taste). The psychophysical scaling method used was magnitude matching with NaCl as the control modality. With this method, subjects rated the intensities of a series of NaCl and PROP solutions. The assumption that the taste of NaCl did not vary with PROP status allowed comparisons of the bitterness of PROP across subjects. Early magnitude matching studies, using sound as the control, had suggested that this assumption was reasonable. However, recent studies challenged that conclusion. Larger samples with more diverse populations, using sound as the control, showed that the taste of NaCl varied with PROP bitterness; supertasters perceived the strongest taste and nontasters, the weakest. Thus our earlier conclusions were conservative because differences between nontasters, medium tasters, and supertasters were concealed by using NaCl as a standard. Using magnitude matching with sound as the standard, or using the Green scale, which employs intensity labels, we found that the differences between PROP groups are larger. Note that the association between PROP status and salt taste is interesting in itself, since variability in salt taste may have important nutritional consequences.

Humans↗
PubMed1998

The perceived bitterness of beer and 6-n-propylthiouracil (PROP) taste sensitivity.

Pelchat and Danowski found a significantly higher proportion of nontasters of 6-n-propylthiouracil (PROP) among children of alcoholics than among children of nonalcohlics, suggesting a possible genetic association between alcoholism and PROP tasting ability. They suggested that nontasters may not find alcohol as bitter as tasters do and may be at greater risk for alcoholism because they like the taste of alcoholic beverages more. In the present study we tested this hypothesis by examining how nontasters, medium tasters, and supertasters of PROP judged the taste of two kinds of beer. Forty-seven males and 53 females between the ages of 21 and 49 rated the perceived bitterness of Budweiser and Pilsner Urquell on the oral Labeled Magnitude Scale (LMS). Subjects also rated their degree of liking or disliking for the two beers on a 9-point Likert scale. PROP papers and the LMS were used to classify subjects into tasting groups. The results lent some support to the hypothesis in that male nontasters liked the taste of Pilsner Urquell better than male supertasters, when they tasted Pilsner Urquell after Budweiser. (This finding was not replicated for females). Also, as subjects' ratings of bitterness for the two beers increased, their degree of liking for the taste decreased. Supertasters rated Pilsner Urquell significantly more bitter than medium tasters. Subjects were asked about their drinking habits, and supertasters reported consuming significantly less beer than nontasters when they first started drinking beer on a regular basis. There were no significant differences in current drinking behavior between tasting groups. These results suggest that supertasters are distinct from nontasters with regard to their taste for beer and may to some degree be protected against alcoholism by their dislike for bitter substances.

Adult↗
PubMed1998

Psychophysical measurement of 6-n-propylthiouracil (PROP) taste perception.

The ability to taste 6-n-propylthiouracil (PROP) is genetically determined. PROP tastes moderately bitter to 'medium tasters' (MT), intensely bitter to 'supertasters' (ST), and tasteless to 'nontasters' (NT). The psychophysical method used to characterize PROP status should capture the entire range of perception, while minimizing context, ceiling and other effects. Magnitude estimation successfully captures the variability in PROP perception, but requires normalization and may be difficult to conduct in industrial settings. Two labeled scales were tested as part of three separate studies (S1, S2 and S3) to measure perceived intensity of PROP and sweeteners. All studies included reportedly healthy volunteers aged 21-62 years recruited at Cultor Food Science in Groton, CT. In S1 [n = 163 (55 males, 108 females)], subjects rated perceived intensity of PROP-saturated paper and sucrose (1.0 M) on the Labeled Magnitude (Green) Scale (LMS) [labeled line with descriptors (no taste--strongest imaginable)]. In S2 [n = 152 (49 males, 103 females)], subjects rated perceived intensity of sucrose (1.0 M) and PROP solutions (0.001 M, 0.0032 M) on the LMS. In S3 [n = 136 (48 males, 88 females)], subjects rated perceived intensity of sucrose (1.0 M) and PROP solutions (0.001 M, 0.0032 M) on a 9-point category scale (1 = not at all; 9 = extremely). In all experiments, water rinses were included between each tastant and PROP was the final stimulus. Statistical analyses included descriptive statistics, regression analysis, and ANOVA. In S1 and S2, those with higher PROP perception perceived sucrose more intensely [(S1: r = 0.32; p < 0.001); (S2: r = 0.25; p < 0.01)]. A higher frequency of females were ST than males. Also, the PROP effect on sweet perception was most evident in female ST. This apparent sex difference may be the result of hormonal variation associated with menstruation. As well, in S1 and S2 subjects aged 20-40 years, females had significantly greater variance among sucrose intensity ratings than males (F = 3.66; p < 0.01), which may be due to hormonal changes with menses. The S3 results failed to show either the positive correlation between PROP and sucrose perception or the sex difference. Thus of the two labeled scales, the LMS appears to be better for assessing PROP perception, as it is continuous and also minimizes ceiling effects. Future research will extend these studies by including sucrose and high intensity sweetener concentration series.

Adult↗
PubMed1998

Comparison of the Green scale versus magnitude estimation for taste perception.

The Green scale is a new psychophysical method that is simple for subjects to use, but its relation with magnitude estimation has yet to be fully characterized. In comparing the consistency between the Green scale and magnitude estimation, we found that the former seems to provide a psychological oral sensation measurement that is different from the latter method. A simple correction formula can be derived.

Humans↗
PubMed1998

Effect of gelatin (a model for salivary PRP) on the sensory astringency of 5-O-caffeoylquinic acid and tannic acid.

The present work investigates differences (triangular tests) between the astringency of 5-O-caffeoylquinic acid (5-CQA) and that of 5-CQA + gelatin. As an overall reference similar tests are reported using tannic acid (which has been shown to elicit a strong response). Finally, a time-intensity study on aqueous solutions of tannic acid (TA), TA + gelatin and gelatin, reveals relevant temporal factors. Although, under the experimental conditions, the majority of comparisons revealed statistically significant differences, in the time-intensity study no significant differences were found between TA + gelatin and gelatin, either for the intensity or the total duration of the response. Moreover, for the fading of the response there was no difference between TA + gelatin and TA. The main temporal contribution to the difference is in the onset of the response and can be related to the spectral differences observed in the earlier studies. It will be argued that these results may represent an important step in our understanding of the mechanisms of astringency.

Chlorogenic Acid↗
PubMed1987

Effect of stimulus range on judgements of sweetness intensity in a lime drink.

The effect of the range of levels of the test stimuli on ratings of sweetness intensity is demonstrated for a lime drink. The results are consistent with Poulton's (1979) suggestion that range effects can be predicted from the deviation of the mean response in a session from the mid-point of the response dimension. It is demonstrated that this range bias can be avoided by adding a readily anchored mid-point (ideal) to the response dimension and selecting stimuli so that the mean response is close to this mid-point. This bias-reducing, relative-to-mid-point procedure also produces a stronger linear relationship between ratings and concentration ratios than does the conventional end-point-anchored intensity rating procedure. The similarity of the linear semi-log functions of response relative to extremely sweet and relative to ideally sweet is taken as evidence that the two types of responses are not independent.

Humans↗
PubMed2001

Taste receptor cells that discriminate between bitter stimuli.

Recent studies showing that single taste bud cells express multiple bitter taste receptors have reignited a long-standing controversy over whether single gustatory receptor cells respond selectively or broadly to tastants. We examined calcium responses of rat taste receptor cells in situ to a panel of bitter compounds to determine whether individual cells distinguish between bitter stimuli. Most bitter-responsive taste cells were activated by only one out of five compounds tested. In taste cells that responded to multiple stimuli, there were no significant associations between any two stimuli. Bitter sensation does not appear to occur through the activation of a homogeneous population of broadly tuned bitter-sensitive taste cells. Instead, different bitter stimuli may activate different subpopulations of bitter-sensitive taste cells.

Animals↗
PubMed1978

Other tastes, other worlds.

The idea of four primary tastes has influenced our concept of the gustatory world of all animals. It has also been the basis for constructing theories of gustatory neural integration. Since natural chemical stimuli are complex mixtures to which responses are multineuronal, difficult questions about integration arise. Answers are usually framed in terms of "labeled line" or "across-fiber" hypotheses. Comparative studies of vertebrate and invertebrate taste reveal in all receptors universal basic parameters that bear on the controversy. Comparative studies also place in more accurate perspective diverse chemically related ecologies and behaviors.

Animals↗
PubMed1978

Taste responses in sheep medulla: changes during development.

Response characteristics of taste neurons in the sheep solitary tract and nuclei alter during development. Solitary tract cells in younger fetuses respond to stimulation of the tongue with fewer salts and acids than do cells in older fetuses, lambs, and adults. Further, responses to specific salts and acids develop in a particular sequence, not randomly. These changes may relate to maturation of taste receptor sites.

Age Factors↗