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PubMed1996

Evaluating the 'Labeled Magnitude Scale' for measuring sensations of taste and smell.

The Labeled Magnitude Scale (LMS) is a semantic scale of perceptual intensity characterized by a quasi-logarithmic spacing of its verbal labels. The LMS had previously been shown to yield psychophysical functions equivalent to magnitude estimation (ME) when gustatory, thermal and nociceptive stimuli were presented and rated together, and the upper bound of the LMS was defined as the 'strongest imaginable oral sensation'. The present study compared the LMS to ME within the more limited contexts of taste and smell. In Experiment 1, subjects used both methods to rate either taste intensity produced by sucrose and NaC1 or odor intensity produced by acetic acid and phenyl ethyl alcohol, with the upper bound of the LMS defined as either the 'strongest imaginable taste' or the 'strongest imaginable odor'. The LMS produced psychophysical functions equivalent to those produced by ME. In, Experiment 2 a new group of subjects used both methods to rate the intensity of three different taste qualities, with the upper bound of the LMS defined as the 'strongest imaginable [sweetness, saltiness, or bitterness]'. In all three cases the LMS produced steeper functions than did ME. Experiment 3 tested the hypothesis that the LMS yields data comparable to ME only when the perceptual domain under study includes painful sensations. This hypothesis was supported when the LMS again produced steeper functions that ME after subjects had been explicitly instructed to omit painful sensations (e.g. the 'burn' of hot peppers) from the concept of 'strongest imaginable taste'. We conclude that the LMS can be used to scale sensations of taste and smell when they are broadly defined, but that it should be modified for use in scaling specific taste (and probably odor) qualities. The implications of these results for theoretical issues related to ME, category-ratio scales and the size of the perceptual range in different sensory modalities are discussed.

Acetic Acid↗
PubMed1997

Intracellular calcium increase in gerbil taste cell by amino acid sweeteners.

Gustatory transduction mechanisms for sucrose and amino acid sweeteners in gerbil taste cells were studied with Ca2+ imaging and whole cell recording techniques. A 100 mM sucrose stimulus with Ca2+ increased the intracellular Ca2+ concentration ([Ca2+]i) in sweet-sensitive taste cells of the taste bud, but the sucrose stimulus without Ca2+ did not change the [Ca2+]i. A 10 mM D-phenylalanine sweet stimulus with or without Ca2+ similarly increased the [Ca2+]i in the taste bud. The addition of 5 microM ionomysin, a Ca(2+)-ionophore, without Ca2+ greatly increased the [Ca2+]i in the taste bud. The application of 10 mM D-phenylalanine stimulus without Ca2+ enhanced the outward K+ current in isolated taste cells. These results suggest that a sugar sweetener such as sucrose induces a depolarization in gerbil taste cells which activates voltage-dependent Ca2+ channels and that a non-sugar sweetener such as D-phenylalanine releases Ca2+ from the internal stores without a depolarization.

Animals↗
PubMed1997

Sensitivity of rat cortical neurons in distinguishing taste qualities by individual and correlative activities.

To examine the possibility that different taste qualities are represented by the correlative activity of cortical gustatory neurons, we made simultaneous recordings of neuron pairs during application of four basic tastes into the oral cavity of anesthetized rats and the following observations were made: (i) in 30 of 67 pairs of taste responsive neurons, peaks (troughs in a few cases) were produced in the cross-correlograms (CCs) during stimulation with some tastants; (ii) the correlative discharges occupied 6-8% of the total spikes discharged by individual neurons during taste stimulation and occurred, in a considerable number of cases, even during stimulation with tastants to which one or both of the component neurons of a pair were apparently non-responding (often sucrose and quinine); (iii) the number of tastants to which a neuron pair responded with a significant correlative activity was often greater than the number of tastants to which the component neurons of the same pair responded with significant changes in discharge rate; (iv) there was no significant difference between the correlative (formation of peaks or troughs in the CC) and individual (change in discharge rate of individual neurons) ways of coding in the sensitivity to distinguish between two taste qualities ranked to be adjacent on the basis of the number of spikes composing the response; and (v) the peaks or troughs appearing in two CCs during stimulations with two kinds of tastants were compared with regard to overlapping of their delay ranges and widths. The spikes in the non-overlapping portion of each peak (suppressed spike number in the case of troughs) are supposed to be able to contribute to two-taste discrimination: the correlated discharges occurring with a delay time that corresponds to the overlapping portion can in no way be judged differently, but the spikes falling in the non-overlapping portion may contribute to the differentiation. The ratio of the non-overlapping portion to the entire peak (or trough) was 0.35 on average. It is concluded that temporal coding of taste qualities seems to operate effectively in the gustatory cortex.

Animals↗
PubMed1999

Taste confusions following gymnemic acid rinse.

The effect of a gymnemic acid (GA) rinse, which simulated a sweet-taste deficit, was measured on human taste perception and identification. Taste ratings showed that GA reduced the intensities of sucrose and aspartame to 14% of pre-rinse levels; over the recovery interval of 30 min, these values increased linearly to 63% of the pre-rinse levels. Repeated presentations of a set of 10 stimuli (five primarily or partly sweet--sucrose, aspartame, and NaCl-sucrose, acid-sucrose and quinine-sucrose mixtures; and five nonsweet--NaCl, KCl, Na glutamate (MSG), quinine HCl and citric acid) for identification following water and GA rinses produced 'taste confusion matrices' (TCMs). Correct identification of the sweet-tasting stimuli was reduced by 23% in presentations closely following the GA rinse, an effect that dissipated with time. Most misidentifications involved sucrose and mixtures containing sucrose. In a second TCM experiment, GA was presented frequently within each session to maintain the sweet taste deficit, which revealed itself as specific confusions. Rinsing with GA impaired discriminability of sweet-nonsweet pairs of stimuli but enhanced discriminability of the aspartame-(NaCl-sucrose) pair. GA had no effect on discriminability of nonsweet stimulus pairs. The results suggest that specific error patterns in the TCM could be used to identify quality-specific taste disorders.

Adult↗
PubMed2000

Decline in taste and odor discrimination abilities with age, and relationship between gustation and olfaction.

It is important to learn about changes in both taste and odor perceptions with increasing age, because the taste of foods we encounter in our daily life is strongly affected by their smell. This study discusses the difference in qualitative taste and odor discrimination between the elderly and the young. Tastants and odorants used in this study were presented not as single stimuli but as a taste mixture (sucrose and tartaric acid) and an odor mixture (beta-phenylethyl alcohol and gamma-undecalactone). The results showed that quality discrimination abilities of the elderly subjects for both taste and odor were significantly lower than those of the young subjects, indicating a decline in quality discrimination abilities related to age. Also, a moderate but significant correlation was observed between the taste discrimination ability and the odor discrimination ability. We measured thresholds for single-taste and odor components in mixtures and compared them between the elderly and the young to investigate the cause for these findings.

Adult↗
PubMed2000

Action of calcitonin gene-related peptide (CGRP) and substance P on neurons in the insular cortex and the modulation of taste responses in the rat.

Using multibarrel electrodes, recordings were made from single neurons in the insular cortex including the cortical taste area (CTA) of urethane-anesthetized rats. The effects of an iontophoretic application of calcitonin gene-related peptide (CGRP) and substance P (SP) on the spontaneous discharges and taste responses were tested. In a total sample of neurons (mostly non-taste), CGRP affected the spontaneous discharges in 35.6% of the 571 neurons studied and SP in 38.3% of the 775 neurons studied. The effects were mostly (approximately 85-87%) facilitatory. Peptide-sensitive neurons were found at a similar frequency in all three insular areas-granular, dysgranular and agranular (areas GI, DI and AI). This is in contrast to previous reports that CGRP receptors were rich in area DI and CGRP-immunoreactive afferents numerous in area AI, but consistent with previous reports that the distribution of SP receptors and SP fibers was dense in the insular cortex. In approximately 40% of the 76 taste neurons recorded from areas GI and DI, the peptides affected the spontaneous discharges (mostly facilitated). When the taste responses were examined during application of the peptides, significant (mainly depressant) effects were seen in 61% of 18 neurons for CGRP and in 70.5% of 17 for SP. Such effects were not recognized on responses to specific taste stimuli and were not correlated with the effects on the spontaneous discharges. The findings indicate that both peptides modify taste coding in CTA neurons presynaptically and/or postsynaptically, independently of the existence of receptors on the neurons.

Animals↗
PubMed2001

Determination of the taste threshold of copper in water.

Copper effects on human health represent a relevant issue in modern nutrition. One of the difficulties in assessing the early, acute effects of copper ingested via drinking water is that the taste of copper may influence the response and the capacity to taste copper in different waters is unknown. The purpose of the study was to determine the taste threshold of copper in different types of water, using soluble and insoluble salts (copper sulfate and copper chloride). Copper-containing solutions (range 1.0-8.0 mg/l Cu) were prepared in tap water, distilled deionized water and uncarbonated mineral water. Sixty-one healthy volunteers (17-50 years of age), with no previous training for sensory evaluation, participated in the study. A modified triangle test was used to define the taste threshold value. The threshold was defined as the lowest copper concentration detected by 50% of the subjects assessed. To evaluate the olfactory input in the threshold value obtained, 15 of 61 subjects underwent a second set of triangle tests with the nose open and clamped, using distilled water with copper sulfate at a concentration corresponding to the individual's threshold. The taste threshold in tap water was 2.6 mg/l Cu for both copper sulfate and copper chloride. The corresponding values for distilled deionized water were 2.4 and 2.5 mg/l Cu for copper sulfate and copper chloride, respectively. In uncarbonated mineral water the threshold values were slightly higher, 3.5 and 3.8 mg/l Cu for copper sulfate and for copper chloride, respectively, which are significantly higher than those observed in tap and distilled waters (P < 0.01, Kruskal-Wallis test). The taste threshold did not change significantly when the nose was clamped. In conclusion, the median values for copper taste threshold were low, ranging between 2.4 and 3.8 mg/l Cu, depending on the type of water.

Adolescent↗
PubMed2002

Slow potentials in taste cells induced by frog glossopharyngeal nerve stimulation.

Intracellular recordings were made from the taste cells of atropinized bullfrogs while the glossopharyngeal (GP) nerve fibres were electrically stimulated. Two types of slow potential, slow hyperpolarizing potentials (HPs) and slow depolarizing potentials (DPs), were induced in the taste cells. The slow HPs appeared when the lingual capillary blood flow was kept above 0.7 mm/s, whereas the slow DPs appeared when the blood flow was slowed down below 0.7 mm/s. The membrane resistance of a taste cell increased during the generation of a slow HP, but decreased during the generation of a slow DP. The reversal potentials for the slow HPs and the slow DPs were recorded at the same membrane potential (-11 to approximately -13 mV). Activation of non-selective cation channels possibly induced the slow DP and inactivation of those channels possibly induced the slow HP in the taste cell membrane. Electrical stimulation of the GP nerve activated a population of C fibres in the nerve and possibly released neurotransmitters from the nerve terminals. Released neurotransmitters might cause modulation of the membrane conductance in taste cells that leads to generation of the slow potentials. The present data suggest that slow HPs and slow DPs evoked in the taste cells of atropinized frogs by GP nerve stimulation are induced by putative neurotransmitters in the taste disc.

Animals↗
PubMed2002

Immunohistochemical investigation of the nitrergic system in the taste organ of the frog, Rana esculenta.

We have studied by immunocytochemistry, the taste discs of the frog, Rana esculenta, with the aim of providing morphological and neurochemical data on the nitrergic system and of assessing the eventual presence of intrinsic neurons associated with the gustatory organs. In taste discs, antibodies against neuronal nitric oxide synthase (nNOS) revealed a positive immunoreaction in the taste receptor cell bodies and processes. The basal cells were also stained. All the fungiform papillae contained intragemmal nerve fibers showing nNOS immunoreactivity; these fiber were mainly located in the basal plexus. Immunoreactive nerve fibers were also visible at the periphery of the papilla-contacting ciliate cells, which form a ring around the taste disc. In conclusion, the findings obtained in this study suggest that the occurrence of nNOS-immunoreactivity in basal cells, taste cells and nerves might reflect a role for nitric oxide in taste mechanisms of Amphibia. The results may also sustain the physiological implication of NO as a molecule involved in the local target function of maintaining the taste bud mucosal integrity and in regulating the blood flow to the epithelium.

Animals↗
PubMed2003

Mouse taste preference tests: why only two bottles?

Two-bottle tests have been used extensively to measure the preference for taste and nutrient solutions but there has been little work with tests involving more than two bottles. Here, we compare the results obtained in two-bottle tests with those obtained in three- and six-bottle tests. In Experiment 1, we measured the preferences for 2 mM saccharin, 50 mM citric acid, 0.3 mM quinine hydrochloride and 75 mM NaCl displayed by 129X1/SvJ (129) and C57BL/6J (B6) mice. Mice drank more taste solution when they received two bottles providing taste solution and one providing water than when they received either a standard two-bottle test or two bottles providing water and one providing taste solution. The three-bottle tests also revealed the left spout side preferences of the 129 strain and were generally better at distinguishing between the 129 and B6 strains (i.e. were more sensitive) than were the two-bottle tests. In Experiment 2, we measured intakes and preferences in tests with six bottles, with one, two, three, four or five containing 75 mM NaCl and the rest containing water. NaCl preferences were monotonically related to the number of NaCl spouts available. A follow-up experiment found similar results whether the index of ingestion was volume intakes or licks. This argues that spillage cannot account for the effect of spout number on taste solution intake. Together, the results suggest that (i) the number of bottles of taste solution and water has a profound influence on taste solution intake and preference, and (ii) three-bottle tests may be more sensitive than two-bottle tests in many circumstances.

Analysis of Variance↗
PubMed2005

Medullary taste responses are modulated by the bed nucleus of the stria terminalis.

Previous studies have shown a modulatory influence of limbic forebrain areas, such as the central nucleus of the amygdala and lateral hypothalamus, on the activity of taste-responsive cells in the nucleus of the solitary tract (NST). The bed nucleus of the stria terminalis (BST), which receives gustatory afferent information, also sends descending axons to the NST. The present studies were designed to investigate the role of the BST in the modulation of NST gustatory activity. Extracellular action potentials were recorded from 101 taste-responsive cells in the NST of urethane-anesthetized hamsters and analyzed for a change in excitability following bilateral electrical stimulation of the BST. The response of NST taste cells to stimulation of the BST was predominately inhibitory. Orthodromic inhibitory responses were observed in 29 of 101 (28.7%) NST taste-responsive cells, with four cells inhibited bilaterally. An increase in excitability was observed in seven of the 101 (6.9%) NST taste cells. Of the 34 cells showing these responses, 25 were modulated by the ipsilateral BST and 15 by the contralateral; four were inhibited bilaterally and two inhibited ipsilaterally and excited contralaterally. The duration of inhibitory responses (mean = 177.9 ms) was significantly longer than that of excitatory responses (35.4 ms). Application of subthreshold electrical stimulation to the BST during taste trials inhibited or excited the taste responses of every BST-responsive NST cell tested with this protocol. NST neurons that were most responsive to sucrose, NaCl, citric acid or quinine hydrochloride were all affected by BST stimulation, although citric acid-best cells were significantly more often modulated and NaCl-best less often modulated than expected by chance. These results combine with excitatory and inhibitory modulation of NST neurons by the insular cortex, lateral hypothalamus and central nucleus of the amygdala to demonstrate extensive centrifugal modulation of brainstem gustatory neurons.

Animals↗
PubMed2006

Depression of gustatory receptor potential in frog taste cell by parasympathetic nerve-induced slow hyperpolarizing potential.

Parasympathetic nerve (PSN) innervates taste cells of the frog taste disk, and electrical stimulation of PSN elicited a slow hyperpolarizing potential (HP) in taste cells. Here we report that gustatory receptor potentials in frog taste cells are depressed by PSN-induced slow HPs. When PSN was stimulated at 30 Hz during generation of taste cell responses, the large amplitude of depolarizing receptor potential for 1 M NaCl and 1 mM acetic acid was depressed by approximately 40% by slow HPs, but the small amplitude of the depolarizing receptor potential for 10 mM quinine-HCl (Q-HCl) and 1 M sucrose was completely depressed by slow HPs and furthermore changed to the hyperpolarizing direction. The duration of the depolarizing receptor potentials depressed by slow HPs prolonged with increasing period of PSN stimulation. As tastant-induced depolarizing receptor potentials were increased, the amplitude of PSN-induced slow HPs inhibiting the receptor potentials gradually decreased. The mean reversal potentials of the slow HPs were approximately -1 mV under NaCl and acetic acid stimulations, but approximately -14 mV under Q-HCl and sucrose stimulations. This implies that when a slow HP was evoked on the same amplitude of depolarizing receptor potentials, the depression of the NaCl and acetic acid responses in taste cells was larger than that of Q-HCl and sucrose responses. It is concluded that slow HP-induced depression of gustatory depolarizing receptor potentials derives from the interaction between gustatory receptor current and slow hyperpolarizing current in frog taste cells and that the interaction is stronger for NaCl and acetic acid stimulations than for Q-HCl and sucrose stimulations.

Animals↗
PubMed2006

Hippocampus, ageing, and taste memories.

Previous studies have shown that ageing may induce deficits in hippocampal-dependent learning and memory tasks, the spatial task being most extensively applied in rats. It is proposed that taste learning and memory tasks may assist in understanding the ageing of memory systems, giving access to a more complete picture. Taste learning tasks allow us to explore a variety of learning phenomena in safe and aversive memories using similar behavioral procedures. In demanding the same sensory, response, and motivational requirements, this approach provides reliable comparisons between the performance of hippocampal lesioned and aged rats in different types of memory. Present knowledge on the effect of both ageing and hippocampal damage in complex taste learning phenomena is reviewed. Besides inducing deficits in hippocampal-dependent phenomena, such as blocking of conditioned taste aversion, while at the same time leaving intact nonhippocampal-dependent effects, such as latent inhibition, ageing is also associated with an increased neophobia by previous aversive taste memories and enhanced taste aversion conditioning which cannot be explained by age-related changes in taste or visceral distress sensitivity. In all, the results indicate a peculiar organization of the memory systems during aging that cannot be explained by a general cognitive decline or exclusively by the decay of the hippocampal function.

Aging↗
PubMed2005

Inhibition of voltage-gated potassium currents by gambierol in mouse taste cells.

Ciguatera is a food poisoning caused by toxins of Gambierdiscus toxicus, a marine dinoflagellate. The neurological features of this intoxication include sensory abnormalities, such as paraesthesia, heightened nociperception, and also taste alterations. Here, we have evaluated the effect of gambierol, one of the possible ciguatera toxins, on the voltage-gated ion currents in taste cells. Taste cells are excitable cells endowed with voltage-gated Na+, K+, and Cl- currents (I(Na), I(K), and I(Cl), respectively). By applying the patch-clamp technique to single cells in isolated taste buds obtained from the mouse vallate papilla, we have recorded such currents and determined the effect of bath-applied gambierol. We found that this toxin markedly inhibited I(K) in the nanomolar range (IC50 of 1.8 nM), whereas it showed no significant effect on I(Na) or I(Cl) even at high concentration (1 microM). The block of I(K) was irreversible even after a 50-min wash. In addition to affecting the current amplitude, we found that gambierol significantly altered both the activation and inactivation processes of I(K). In conclusion, unlike other toxins involved in ciguatera, such as ciguatoxins, which affect the functioning of voltage-gated sodium channels, the preferred molecular target of gambierol is the voltage-gated potassium channel, at least in taste cells. Voltage-gated potassium currents play an important role in the generation of the firing pattern during chemotransduction. Thus, gambierol may alter action potential discharge in taste cells and this could be associated with the taste alterations reported in the clinical literature.

Action Potentials↗
PubMed2002

Taste and olfactory disturbances after upper and middle third facial fractures: a preliminary study.

To estimate smell and taste after traumatic disturbances, the authors questioned a sample of 92 patients who underwent surgical treatment for upper third and/or middle third facial fractures between January 1, 1988, and May 31, 1996, at the Department of Maxillofacial Surgery, University of Rome "La Sapienza," Italy. A total of 86 patients included in the study had a facial fracture sustained during a motor vehicle accident. Twenty-nine patients reported smell and/or taste after the traumatic disturbance. Of these 29 patients, 8 patients had hyposmia and/or anosmia without taste deficit, 10 patients had taste disturbances without smell loss, and 11 patients noted disturbance in both smell and taste. The authors encountered posttraumatic smell disturbances in 19 patients in their sample. Nasozygomatic-Le Fort fractures, fronto-orbital fractures, and pure Le Fort fractures were found to determine posttraumatic smell disturbances in these 19 patients. Nasal fractures, nasoorbital-ethmoidal fractures, ethmoidal fractures, frontal-Le Fort fractures, and nasal-Le Fort fractures did not determine any olfactory dysfunction. Posttraumatic hypogeusia and ageusia were found in 21 patients and was caused by nasozygomatic-Le Fort fractures, fronto-orbital fractures, and pure Le Fort fractures. The authors did not find any taste deficits after patients sustained other kinds of facial fractures. In the 11 patients observed, disturbances in both smell and taste were noted. Nasozygomatic-Le Fort fracture was the most common in these 11 patients. At 5 years' of follow-up, the results indicate that hypogeusia and hyposmia are connected with the etiology of fracture, the violence of the trauma, and the involvement of specific facial bone regions.

Accidents, Traffic↗
PubMed1998

Taste and smell complaints in HIV-infected patients.

OBJECTIVES: To define the scope of taste and smell (chemosensory) complaints amongst HIV-infected persons in the study population; to evaluate the clinical factors associated with chemosensory complaints; and to determine the impact of chemosensory complaints on quality of life. DESIGN: Cross-sectional survey. SETTING: Tertiary care university medical center clinic. PARTICIPANTS: A total of 207 HIV-infected patients. MAIN OUTCOME MEASURES: Chemosensory complaint score from taste and smell questionnaire and quality of life scores from the Medical Outcomes Study HIV Health Survey (MOS-HIV). RESULTS: A total of 144 patients (70%) reported chemosensory complaints, 91 (44%) reported both taste and smell complaints, 47 (23%) reported only taste complaints, and six (3%) reported only smell complaints. Many patients complained that drugs interfered with their sense of taste, or that medications tasted bad. Higher chemosensory complaint scores were associated with a greater number of medications taken, tobacco use, and hay fever. Patients with chemosensory complaints had significantly lower scores in all domains of the MOS-HIV than those without complaints. Quality of life as measured by the MOS-HIV was lower in patients with chemosensory complaints even after controlling for number of AIDS diagnoses, number of medications, CD4 cell count, and HIV-1 viral load. CONCLUSIONS: Chemosensory complaints were common in the patient population and were associated with a poor quality of life. Medications played an important role in chemosensory complaints. Measures to optimize taste and smell function may improve quality of life and medication adherence, and prevent complications such as inadequate oral intake, malnutrition, weight loss, and ultimately wasting.

Adult↗
PubMed2004

The place of osmophobia and taste abnormalities in migraine classification: a tertiary care study of 1237 patients.

This study evaluates osmophobia and taste abnormalities in relationship to sensitivity and specificity in the classification of migraine. Consecutive International Headache Society (IHS) classified patients (n = 1237) were evaluated. Symptoms were graded from 0 to 3. Osmophobia and taste abnormalities were tested for sensitivity and specificity in migraine diagnosis. The patients were 85.4% female and their mean age was 38.1 years. Of 673 patients 24.7% complained of osmophobia, and 24.6% of 505 complained of taste abnormalities. In the absence of nausea and vomiting the combinations of two symptoms gave the following sensitivity and specificity percentages, respectively: photophobia and phonophobia, 10.6 and 84.9; photophobia and osmophobia, 1.1 and 99.0; phonophobia and osmophobia, 1.1 and 98.6; photophobia and taste abnormality, 9.6 and 99.0; phonophobia and taste abnormality, 9.6 and 98.8; and osmophobia and taste abnormality, 4.2 and 99.4. Osmophobia and taste abnormalities were demonstrated to be very specific in diagnosing migraine IHS 1.1-1.6, but very insensitive.

Adolescent↗
PubMed2001

The science and complexity of bitter taste.

Food choices and eating habits are largely influenced by how foods taste. Without being the dominant taste sensation, bitter taste contributes to the complexity and enjoyment of beverages and foods. Compounds that are perceived as bitter do not share a similar chemical structure. In addition to peptides and salts, bitter compounds in foods may include plant-derived phenols and polyphenols, flavonoids, catechins, and caffeine. Recent studies have shown that humans possess a multitude of bitter taste receptors and that the transduction of bitter taste may differ between one compound and another. Studies of mixture interactions suggest further that bitter compounds suppress or enhance sweet and sour tastes and interact with volatile flavor molecules. Caffeine, a natural ingredient of tea, coffee, and chocolate, has a unique flavor profile. Used as a flavoring agent, it enhances the sensory appeal of beverages. Research developments on the genetics and perception of bitter taste add to our understanding of the role of bitterness in relation to food preference.

Aging↗