Gonadal hormones and sensory function.
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Animals↗
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Results for “Taste Threshold”
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Evaluation of recycled HDPE milk bottles for food applications.
The possibilities of recycling milk-contaminated HDPE were investigated. Bottles were blown of respectively untreated, caustic-washed and caustic-washed/steam-stripped/air-dried recycled material. The migration characteristics of the different bottles were compared using various food simulants, as well as their sensorial and mechanical properties. From the analytical and sensorial experiments, it was shown that the untreated and caustic-washed recycled material could not be considered as a food packaging material. A high number of compounds able to migrate were detected, causing an off-flavour which could easily be recognized. The steam-stripped recycled material however, seemed to perform almost as well as its corresponding virgin material. Only low amounts of compounds able to migrate could be detected, resulting in a packaging material characterized by excellent sensorial properties which could not be distinguished from its virgin material. Furthermore it was proved that the mechanical properties of the recycled material did not change during the recycling process.
Air↗
Sensory detection of glutaraldehyde in drinking water-emergence of sensitivity and specific anosmia.
A study of 30 young adults (15 males, 15 females), screened to have normal olfaction, measured detection of the flavor of glutaraldehyde, a biocide that could occur in disinfected potable water. Over the range of interest, up to 100 p.p.m., flavor derived from olfactory stimulation. Higher concentrations would cause oral irritation. Fourteen subjects failed to detect the glutaraldehyde in the first of four sessions of testing. Eight of the 14 (seven males, one female) continued to exhibit the anosmia throughout testing. The other six (one male, five females) began to detect the material in session two and exhibited increasing sensitivity over sessions two to four. Their average sensitivity never reached that of the 16 subjects who evinced no anosmia and who also improved their performance over sessions. The combined group of 22 could detect 17 p.p.m. Less thorough testing would have yielded much higher values. Specific anosmia for this dialdehyde has precedence in anosmia for various monoaldehydes, most notably isobutyraldehyde. The positive influence of experience with a material on detection has been found previously, most intriguingly by Wysocki and colleagues, who showed that experience could differentially induce sensitivity to the odorant androstenone and suggested that the phenomenon might occur for other compounds. Glutaraldehyde appears to be one, perhaps of many.
Adolescent↗
[Olfactory and gustatory sweating--case report on reflex facial hyperhidrosis].
Localised hyperhidrosis is comparatively rare among the vegetative disorders. A case of pathological gustatory and olfactory sudation is reported, with the sequence of symptoms corresponding to that of the Frey syndrome. Working from the reflex nature of the phenomen, the paper puts forward a model to account for the delayed onset of the manifestation following a peripheral lesion. It is assumed that readjustment of the reflex excitation level takes place according to a modification in peripheral afference, and that a decompensation of the central control mechanisms results in a pathological enhancement of the reflex. The hypothesis of peripheral efferentisl denervation hypersensitivity appears insufficient to account for the delay in manifestation, or even to account for the classic Frey syndrome following an affection of the parotid gland.
Humans↗
Effect of psychotropic drugs on taste responses in young and elderly persons.
The taste of six psychotropic drugs (amitriptyline HCl, clomipramine HCl, desipramine HCl, imipramine HCl, doxepin HCl, and trifluoperazine HCl) can be detected at concentrations of 0.1 mM or less in both young and elderly individuals. At concentrations 4 times higher than the detection thresholds, these drugs have bitter as well as other unpleasant taste properties. Oral exposure to these drugs not only induces a taste from the drug itself but also alters taste perception of other compounds such as NaCl and sucrose. These results indicate that both hypogeusia and dysgeusia may be induced by psychotropic medications.
Adult↗
Quantitative studies and sensory analyses on the influence of cultivar, spatial tissue distribution, and industrial processing on the bitter off-taste of carrots (Daucus carota l.) and carrot products.
Although various reports pointed to 6-methoxymellein (1) as a key player imparting the bitter taste in carrots, activity-guided fractionation experiments recently gave evidence that not this isocoumarin but bisacetylenic oxylipins contribute mainly to the off-taste. Among these, (Z)-heptadeca-1,9-dien-4,6-diyn-3-ol (2), (Z)-3-acetoxy-heptadeca-1,9-dien-4,6-diyn-8-ol (3), and (Z)-heptadeca-1,9-dien-4,6-diyn-3,8-diol (falcarindiol, 4) have been successfully identified. In the present study, an analytical procedure was developed enabling an accurate quantitation of 1-4 in carrots and carrot products. To achieve this, (E)-heptadeca-1,9-dien-4,6-diyn-3,8-diol was synthesized as a suitable internal standard for the quantitative analysis of the bisacetylenes. On the basis of taste activity values, calculated as the ratio of the concentration and the human sensory threshold of a compound, a close relationship between the concentration of 4 and the intensity of the bitter off-taste in carrots, carrot puree, and carrot juice was demonstrated, thus showing that compound 4 might offer a new analytical measure for an objective evaluation of the quality of carrot products. Quantitative analysis on the intermediate products in industrial carrot processing revealed that removing the peel as well as green parts successfully decreased the concentrations in the final carrot puree by more than 50%.
Daucus carota↗
Interactions between stimuli with different taste qualities.
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Caffeine↗
Migration of volatile degradation products into ozonated water from plastic packaging materials.
Migration of volatile degradation products from poly(ethylene terephthalate) (PET) and high-density polyethylene (HDPE) bottles, polypropylene (PP) caps and ethyl vinyl acetate (EVA) liners into ozonated water was measured. Polymer strips were immersed in deionized and distilled water with ozone concentrations of 0.5, 2.5 and/or 5 mg kg(-1) inside 35-ml vials, which were clamp-sealed and stored at 40 degrees C for 10 days. A purge-and-trap unit was developed to extract volatile products from the ozonated water in vials. The extractables were trapped in an adsorbent tube and analysed using a GC-MS coupled with an automated thermal desorber (ATD). Mass spectra were interpreted by comparison with a NIST mass spectral library, and an internal standard method was used to quantify the extractables of interest. Several volatile compounds found in ozonated water that had been in contact with PP, EVA and HDPE polymers included butanal, pentanal, hexanal, heptanal, octanal, nonanal, 2,2-dimethyl propanal, 3-hexanone, 2-hexanone and heptanone. These compounds could cause off-taste and off-odour with a low organoleptic threshold. In general, the concentrations of these volatile compounds increased with an increased exposure to ozone. The highest concentration found was 14.1 +/- 0.6 microg kg(-1) for hexanal with a 5 mg kg(-1) ozone treatment of PP caps. Even at a treatment level of 5 mg kg(-1) ozone, which is greater than 10 times the current regulatory limits for bottled water, the extractables migrating from those polymers were within the levels permitted by the FDA. For the PET sample, no significant peaks were observed before or after ozonation. These results imply that PP caps containing EVA liners may be major sources of off-odour and taste in ozonated bottled water.
Disinfection↗
Gustatory function after third molar extraction.
OBJECTIVE: The purpose of this study was to determine the severity and time course of taste changes after extraction of all 4 third molars. STUDY DESIGN: Taste function in 17 patients was measured before third molar surgery and at 1 month and 6 months after surgery. Two tests were administered: a whole-mouth, above-threshold test in which subjects sipped, expectorated, and then rated the intensities and identified the taste qualities of various solutions, and a localized test in which subjects rated and identified solutions painted with cotton swabs on different oral sites. RESULTS: Intensity ratings for solutions in the whole-mouth test were reduced by approximately 14% for NaCl, citric acid, and quinine hydrochloride at 1 month after surgery and had not recovered by 6 months after surgery for citric acid (P<.02). The taste quality of NaCl was identified correctly less frequently after third molar extraction. Perceived taste intensity on discrete areas of the tongue was significantly reduced after surgery (P<.05). Patients with the most severely impacted molars gave the lowest taste intensity ratings to whole-mouth test solutions at 6 months after surgery (P<.02). In contrast, taste function in a group of subjects who received only local dental anesthesia was not affected. CONCLUSIONS: Gustatory deficits occur after third molar extraction, persist for as long as 6 months after surgery, and appear to be associated with depth of impaction.
Adolescent↗
Lingual tactile acuity, taste perception, and the density and diameter of fungiform papillae in female subjects.
A growing body of evidence suggests that individuals who differ in taste perception differ in lingual tactile perception. To address this issue, spatial resolution acuity was estimated for 83 young adult females (52 Asians and 31 Caucasians) by their ability to examine with the tongue and identify embossed letters of the alphabet. Ratings of the magnitude of the bitterness of 0.0032M 6-n-propylthiouracil (PROP) were obtained to characterize subjects' taste perception. The density and diameter of fungiform papillae on the anterior tongues of the Asian subjects were measured also. Subjects who rated the bitterness of PROP as very or intensely strong (supertasters) were found to be about 25% more tactually acute than subjects who rated the bitterness as moderate to strong (medium tasters) and twice as acute as subjects who rated it as nondetectable or weak (non-tasters; P<.0001): The threshold heights for letter recognition averaged 2.8, 3.5 and 5.4 mm, respectively, for the Asian subjects and 2.6, 3.2, and 5.1 mm for the Caucasian subjects. The thresholds correlated highly with subjects' ratings of bitterness (rho=-0.84, P<.0001), and for the Asian subjects with the density (rho=-0.84, P<.0001) and diameter (rho=0.66, P<.0001) of fungiform papillae. Mean densities varied from 54.4 cm(-2) (non-tasters) to 106.5 cm(-2) (medium tasters) to 143.7 cm(-2) (supertasters; P<.0001). These findings confirm that individuals who differ in taste (PROP) sensitivity also differ in lingual tactile acuity. Tactile and taste sensitivities covary and reflect individual differences in the density and diameter of fungiform papillae on the anterior tongue.
Adolescent↗
Old-age deficits in the sense of smell as gauged by thresholds, magnitude matching, and odor identification.
Twenty elderly subjects (70-90 years old) and 20 young control subjects (18-24 years old) underwent three kinds of olfactory testing: absolute thresholds to three odorants (d-limonene, iso-amyl butyrate, benzaldehyde), magnitude matching of these odorants to salt tastes, and odor identification of 30 common substances. For all three odorants elderly subjects' mean threshold significantly exceeded that of the young by about ninefold for d-limonene, about threefold for benzaldehyde, and about twofold for iso-amyl butyrate. These threshold differences predict approximate concentration differences necessary to arouse the same estimated odor strength above the threshold for the elderly and the young. Young subjects also scored better than the elderly in odor identification, even when subjects were given four alternatives from which to select the correct label. Unimpaired olfactory functioning is uncommon in the elderly; correlational tests show that as a group the young have better olfactory ability and show more interindividual uniformity.
Adolescent↗
[Variations in the taste function of smokers].
Cigarette smoke is linked to many pathologies and also affects a very important aspect of human physiology that is taste. In fact already in the past years, researchers have worked on this phenomenon and have come to the conclusion that smoke influences the perception of bitter taste. In our study we researched the detection and identification threshold in thirty smokers, for the citric acid, quinine, sodium chloride and saccharose, and it turned out that smokers suffer a raise in quinine identification and sodium chloride detection and identification threshold. On the basis of the results obtained with sodium chloride, a theory on hypertension etiopathogenesis is suggested.
Adult↗
Molecular definition of black tea taste by means of quantitative studies, taste reconstitution, and omission experiments.
Recently, bioresponse-guided fractionation of black tea infusions indicated that neither the high molecular weight thearubigens nor the theaflavins, but a series of 14 flavon-3-ol glycopyranosides besides some catechins, might be important contributors to black tea taste. To further bridge the gap between pure structural chemistry and human taste perception, in the present investigation 51 putative taste compounds have been quantified in a black tea infusion, and their dose-over-threshold (Dot) factors have been calculated on the basis of a dose/threshold relationship. To confirm these quantitative results, an aqueous taste model was prepared by blending aqueous solutions of 15 amino acids, 14 flavonol-glycosides, 8 flavan-3-ols, 5 theaflavins, 5 organic acids, 3 sugars, and caffeine in their "natural" concentrations. Sensory analyses revealed that the taste profile of this artificial cocktail did not differ significantly from the taste profile of the authentic tea infusion. To further narrow the number of key taste compounds, finally, taste omission experiments have been performed, on the basis of which a reduced recombinate was prepared containing the bitter-tasting caffeine, nine velvety astringent flavonol-3-glycosides, and the puckering astringent catechin as well as the astringent and bitter epigallocatechin-3-gallate. The taste profile of this reduced recombinate differed not significantly from that of the complete taste recombinate, thus confirming these 12 compounds as the key taste compounds of the tea infusion. Additional sensory studies demonstrated for the first time that the flavanol-3-glycosides not only impart a velvety astringent taste sensation to the oral cavity but also contribute to the bitter taste of tea infusions by amplifying the bitterness of caffeine.
Amino Acids↗
The taste and mechanical response properties of neurons in the parvicellular part of the thalamic posteromedial ventral nucleus of the rat.
A total of 41 taste and 17 mechanoreceptive neurons were recorded in the parvicellular part of the posteromedial ventral nucleus of the thalamus (VPMpc) of amobarbital-anesthetized rats. Most of the taste neurons were located in the rostral part, while most of the mechanoreceptive neurons were located in the middle part of the VPMpc. Stimulation of the whole oral cavity with four basic taste stimuli produced smaller mean response magnitudes in these thalamic taste neurons than in the parabrachio-thalamic (P-T) taste relay neurons. Receptive fields (RFs) for most of the 21 taste neurons examined were located on the tongue or on the tongue and palate, as with P-T relay neurons. Some neurons had RFs ipsilaterally in the oral cavity, as do P-T relay neurons; but others had RFs contralaterally or bilaterally. Several neurons had large RFs in comparison with those of P-T relay neurons. A majority of the thalamic taste neurons were also mechanosensitive, and their RFs were larger for mechanical stimulation than for taste stimulation. Many (12/17) of the mechanoreceptive neurons had a low response threshold, activated by stroking the tissue with a glass rod; and others had a high response threshold, activated by a pinch with a pair of non-serrated forceps. Their RFs were contralaterally or bilaterally located on either the tongue, or palate or on both regions. One taste neuron and some mechanoreceptive neurons were also excited by mechanical stimulation on the cheek or lip. These observations may represent integrative processes for taste and mechanical oral information at the thalamic level.
Action Potentials↗
Response characteristics of rat taste cells to potassium benzoate.
The rat taste cells responded to K-benzoate solutions higher than the threshold concentrations (0.03-0.3 M) with a depolarizing receptor potential, but they responded to K-benzoate lower than the thresholds with a hyperpolarizing receptor potential. In either depolarizing or hyperpolarizing receptor potentials the rise time decreased with increasing amplitude, but the fall time increased with increasing amplitude. During generation of either depolarizing or hyperpolarizing receptor potentials the input resistance of taste cells decreased with increasing amplitude. Application of the mixtures of various concentrations of NaCl and 0.05 M K-benzoate resulted in a reduction of receptor potential amplitude, as compared with that evoked by application of NaCl alone. It is concluded that a depression of gustatory neural impulse frequency by low concentrations of K-benzoate is mainly due to the hyperpolarizing receptor potential of taste cells elicited by the K-benzoate solutions.
Animals↗
Bidirectional synaptic transmission in Necturus taste buds.
Pairs of taste cells were impaled with intracellular recording microelectrodes in intact taste buds in slices of Necturus lingual epithelium. Applying short pulses of 140 mM KCl or 200 mM CaCl2 solutions to the apical pore elicited receptor potentials in taste receptor cells. Chemostimulation of receptor cells elicited postsynaptic responses in basal cells in the taste bud. Postsynaptic responses in basal cells had a threshold for activation and did not saturate with increasing doses of chemical stimulus applied to the receptor cells. We directly depolarized individual receptor cells and tested whether this would evoke postsynaptic responses in basal cells. Depolarizing receptor cells to approximately 0 mV evoked small depolarizing responses in basal cells in 16% of the experiments. The properties of these responses were consistent with their being mediated by a chemical synapse. A comparison of the responses in basal cells evoked by depolarizing single receptor cells, with responses evoked by stimulating the entire receptor cell population with KCl suggests that there is extensive synaptic convergence from receptor cells onto each basal cell. We also tested whether electrical excitation of basal cells would elicit (retrograde) synaptic responses in receptor cells. Single depolarizing pulses (up to 1 sec duration) applied to basal cells through the intracellular recording microelectrode never evoked synaptic responses in receptor cells. However, when repetitive electrical stimuli were applied to basal cells (four to six 1 sec depolarizations to approximately 0 mV every 12 sec) we observed prolonged effects on receptor cells in 11 of 23 experiments. These effects included an increase in the amplitude of receptor potentials elicited by KCI (mean +/- SD = +19 +/- 5%), an increase in membrane input resistance of receptor cells (+27 +/- 11%), and a hyperpolarization of receptor cells (3-10 mV). In control experiments, repetitive stimulation of one receptor cell never elicited such effects in another receptor cell. We investigated the possibility that serotonin (5-HT), released from basal cells, mediated the above modulatory effects on receptor cells. Bath-applied 5-HT (100 microM) mimicked the effects produced by repetitive basal cell stimulation (KCI responses increased by 23 +/- 12%; input resistance increased by 24 +/- 11%; hyperpolarization of 5-15 mV; N = 14). We conclude that basal cells release 5-HT onto adjacent taste receptor cells and that this enhances the electrotonic propagation of receptor potentials from the apical (chemosensitive) tip to the basal (synaptic) processes of receptor cells. The net effect is that activation of basal cells effectively increases the chemosensitivity of taste receptor cells.
Animals↗
Temporal properties of the human taste system.
An attempt to apply linear systems methods to the temporal properties of the human taste system is described. The percentage modulation in concentration required to detect a fluctuation in intensity was measured as a function of frequency of modulation. Both a sine-wave and a square-wave input were used. The sensitivity of the taste system at its maximum, and also at the low frequencies, was greater than expected from previous work based on classical methodology. The sensitivity of the taste system at its maximum, and also at the low frequencies, was greater then expected from previous work base on classical methodology. The sensitivity of the taste system to the various qualities was, in decreasing order, salty, sweet, sour, and bitter. The taste system in insensitive to frequencies above about 5 Hz. Except for bitter, representatives of the various taste qualities yielded similar functions within qualities.
Adaptation, Physiological↗
Differential effects of removing the glucose or saccharin components of a glucose-saccharin mixture in a successive negative contrast paradigm.
When rats experience an unexpected decrease in reward value, e.g., from 32% sucrose to 4% sucrose, consummatory behavior abruptly decreases to a level below control subjects that only experience the lesser reward, a phenomenon known as Successive Negative Contrast (SNC). In food deprived rats experiencing downshifts in sucrose concentration, SNC dissipates in 3-4 days, as consummatory behavior in shifted rats recovers to the level of unshifted controls. In Experiment 1 food deprived rats that were given 5 min daily access to a 2% glucose-0.15% saccharin mixture, and subsequently shifted to 2% glucose alone, displayed a dramatic SNC effect relative to rats that only received 2% glucose. This SNC effect was primarily manifested as a decrease in the number of consummatory bursts initiated. Interestingly, intake failed to recover to control levels during eight daily postshift sessions. However, in Experiment 2 subjects that were shifted from the same glucose-saccharin mixture to 0.15% saccharin alone failed to show SNC rather, intake fell to the level of control animals which only received 0.15% saccharin. The data from Experiment 1, in conjunction with previous studies utilizing non-deprived rats, quinine adulteration, or shifts from sucrose to saccharin, show that reductions in taste value can produce contrast effects, but suggest that a threshold caloric value is necessary for recovery. The data from Experiment 2 may suggest that saccharin and glucose do not contribute equally to the enhanced palatability of the mixture.
Analysis of Variance↗