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PubMed2000

Effects of Momordica charantia powder on serum glucose levels and various lipid parameters in rats fed with cholesterol-free and cholesterol-enriched diets.

The effects of dietary bitter melon (Momordica charantia) freeze-dried powder on serum glucose level and lipid parameters of the serum and liver were studied in rats fed diets supplemented with and without cholesterol. Rats were fed the diets for 14 days containing bitter melon freeze-dried powder at the level of 0.5, 1 and 3% without an added dietary cholesterol (experiment I) and those containing bitter melon at the level of 1% with or without 0.5% cholesterol and 0.15% bile acid (experiment II). No adverse effect of dietary bitter melon powder on growth parameters and relative liver weight were noted. Dietary bitter melon resulted in a consistent decrease in serum glucose levels in rats fed cholesterol-free diets, but not in those fed cholesterol-enriched diets, although no dose-response was noted. Addition of cholesterol to the diets as compared to those without added cholesterol caused hypercholesterolemia and fatty liver. Bitter melon had little effect on serum lipid parameters, except for high density lipoprotein (HDL)-cholesterol; HDL-cholesterol levels tended to decrease by dietary cholesterol, while they were consistently elevated by dietary bitter melon both in the presence and absence of dietary cholesterol, indicating an antiatherogenic activity of bitter melon. In addition, bitter melon exhibited a marked reduction in the hepatic total cholesterol and triglyceride levels both in the presence and absence of dietary cholesterol; the reduction of triglyceride levels in the absence of dietary cholesterol was in a dose-dependent manner. These results suggest that bitter melon can be used as a health food.

Animals↗

PubMed2006

Taste masking analysis in pharmaceutical formulation development using an electronic tongue.

The purpose of this study is to assess the feasibility for taste masking and comparison of taste intensity during formulation development using a multichannel taste sensor system (e-Tongue). Seven taste sensors used in the e-Tongue were cross-selective for five basic tastes while having different sensitivity or responsibility for different tastes. Each of the individual sensors concurrently contributes to the detection of most substances in a complicated sample through the different electronic output. Taste-masking efficiency was evaluated using quinine as a bitter model compound and a sweetener, acesulfame K, as a bitterness inhibitor. In a 0.2 mM quinine solution, the group distance obtained from e-Tongue analysis was reduced with increasing concentration of acesulfame K. This result suggests that the sensors could detect the inhibition of bitterness by a sweetener and could be used for optimization of the sweetener level in a liquid formulation. In addition, the bitterness inhibition of quinine by using other known taste-masking excipients including sodium acetate, NaCl, Prosweet flavor, and Debittering powder or soft drinks could be detected by the e-Tongue. These results further suggest that the e-Tongue should be useful in a taste-masking evaluation study on selecting appropriate taste-masking excipients for a solution formulation or a reconstitution vehicle for a drug-in-bottle formulation. In another study, the intensity of the taste for several drug substances known to be bitter was compared using the e-Tongue. It was found that the group distance was 695 for prednisolone and 686 for quinine, which is much higher than that of caffeine (102). These results indicate that the taste of prednisolone and quinine is stronger or more bitter than that of caffeine as expected. Based on the group distance, the relative intensity of bitterness for these compounds could be ranked in the following order: ranitidine HCl>prednisolone Na>quinine HCl approximately phenylthiourea>paracetamol>>sucrose octaacetate>caffeine. In conclusion, the multichannel taste sensor or e-Tongue may be a useful tool to evaluate taste-masking efficiency for solution formulations and to compare bitterness intensity of formulations and drug substances during pharmaceutical product development.

Biosensing Techniques↗

PubMed2003

Role of cucurbitacin C in resistance to spider mite (Tetranychus urticae) in cucumber (Cucumis sativus L.).

Cucurbitacins are bitter triterpenoid compounds that are toxic to most organisms and occur widely in wild and cultivated Cucurbitaceae. The only cucurbitacin identified in Cucumis sativus is cucurbitacin C. The bitter taste of cucumber has been correlated with resistance to the spider mite Tetranychus urticae, but a quantitative relationship has not been established. We determined the spider mite resistance and cucurbitacin C content in the dihaploid progeny derived from the F1 generation of a cross between a bitter, spider-mite-resistant cucumber line and a bitter-free, spider-mite-susceptible line. The ratio of the number of bitter to bitter-free dihaploids conformed to the expected 1:1 ratio, based on a monogenic segregation pattern. Genetic analysis ascribed 69% of the variance of the difference in spider mite survival rate to the bitterness locus. Within the group of bitter dihaploids, cucurbitacin C content was significantly correlated with spider mite resistance. Thus, a quantitative relationship between cucurbitacin C content and spider mite resistance could be established.

Adaptation, Physiological↗

PubMed1987

Interactions between CO2 oral pungency and taste.

Two experiments are reported in which the perceptual interactions between oral pungency, evoked by CO2, and the taste of each of four tastants--sucrose (sweet), quinine sulfate (bitter), sodium chloride (salty), and tartaric acid (sour)--were explored. In experiment 1 the effect of three concentrations of each tastant on the stimulus-response function for perceived oral pungency, in terms of both rate of change (slope) and relative position along the perceived pungency axis, was determined. In experiment 2 the effect of three concentrations of CO2 on the stimulus-response function for the perceived taste intensity of each tastant was examined. Results show that the characteristics of the mutual effects of tastant and pungent stimulus depend on the particular tastant employed. Sucrose sweetness and CO2 oral pungency have no mutual effect; sodium chloride saltiness or tartaric acid sourness and CO2 oral pungency show mutual enhancement; and quinine sulfate bitterness abates CO2 oral pungency, whereas CO2 has a double and opposite effect on quinine sulfate bitterness--at low concentrations of bitter tastant CO2 enhances bitterness, and at high concentrations of bitter tastant CO2 abates bitterness. It is suggested that the perceptual attributes of saltiness and sourness are closer, from a qualitative point of view, to oral pungency than are the attributes of bitterness and sweetness.

Adult↗

PubMed2005

Validation of a rat behavioral avoidance model from a drug delivery perspective.

Conventional taste-masking strategies are used to overcome the bitter taste perception of pharmaceuticals by coating the drug particles and/or adding flavoring agents. However, for certain product categories such as rapid dissolve sublingual tablets, taste-masking is challenging. Programs exploring such formulation strategies in the LO-CS phase or post CS phase possess very little toxicological information available in order to conduct human taste panel studies. The potential of a bitter taste perception can present a significant business risk. The objective of the study was to validate a rat behavioral avoidance model that identifies bitter-tasting compounds. Most classic bitter substances elicit a response in the micromolar concentration range while most drugs elicit a response in the millimolar range, hence a validation exercise was conducted to examine if the existing biological model was sensitive enough to identify known bitter tasting drugs as such. Five compounds: ergotamine tartrate, fluoxetine, sucrose, sumatriptan and povidone were chosen to represent a spectrum of compounds. The bitter tasting compounds were identified as such in the model. Based on these results, the assay may serve as a useful surrogate test to identify compounds that may have bitter taste issues.

Animals↗

PubMed2001

Debittering of protein hydrolyzates.

Enzymatic hydrolysis of proteins frequently results in bitter taste, which is due to the formation of low molecular weight peptides composed of mainly hydrophobic amino acids. Methods for debittering of protein hydrolyzates include selective separation such as treatment with activated carbon, extraction with alcohol, isoelectric precipitation, chromatography on silica gel, hydrophobic interaction chromatography, and masking of bitter taste. Bio-based methods include further hydrolysis of bitter peptides with enzymes such as aminopeptidase, alkaline/neutral protease and carboxypeptidase, condensation reactions of bitter peptides using protease, and use of Lactobacillus as a debittering starter adjunct. The causes for the production of bitter peptides in various food protein hydrolyzates and the development of methods for the prevention, reduction, and elimination of bitterness as well as masking of bitter taste in enzymatic protein hydrolyzates are presented.

Journal Article↗

PubMed2001

[Dyspeptic pain and phytotherapy--a review of traditional and modern herbal drugs].

Gastrointestinal complaints rank among the most frequently reasons why people asking for medical advice. About 15-30% of the adult patients suffer from different various functional dyspeptic conditions. The therapy of functional gastrointestinal disorders is one of the domains of phytotherapeutic treatments. From ancient times on, bitter herbal drugs played a very important role in the therapy of patients with dyspeptic symptoms. The mechanisms of action of the bitters are not completely understood. But there are indications that they sensorially stimulate at even very small concentrations sensorially the secretion of the stomach as well as the digestive glands and strengthen the smooth musculature of the digestive tract (via the gustatory system, N. vagus and the enteric nervous system). Across the enteral nervous system the strengthened digestive tract seems to stimulate the CNS, leading to a general tonification. At higher dosages bitters probably directly affect the mucous membranes of the stomach and the bowel. Bitters often are combined with essential oils (some volatile oils as aromatic bitters, drug combinations of a volatile oil with a bitter). Essential oils act primarily as spasmolytics, carminatives and local anesthetics. In the last years several controlled studies were carried out with phytotherapeutic combinations (e.g. with Iberis amara, caraway oil, peppermint oil, curcuma extract, ginger extract) in which the herbal drugs proved to be superior compared to placebo and were as effective as prokinetics (studies according to evidence-based medicine). The traditional phytotherapeutic approach is based upon the illness- as well as the patient-related investigations referring to the effectiveness of bitter, acrid- and essential-oil drugs. Such a treatment is supported by a rich amount of various of kinds of individual empirical experience (experience-based phytotherapy). Important traditional medical systems like the Traditional Chinese Medicine, the Ayurvedic Medicine as well as the European 'Humoral Medicine' consider different aspects of the sick human being, like the constitution of the patient (holistic approach), and take qualities of herbal drugs, vegetarian food, and spices into account for therapeutic purposes.

Drugs, Chinese Herbal↗

PubMed2000

Application of dry elixir system to oriental traditional medicine: taste masking of peonjahwan by coated dry elixir.

Peonjahwan, an oriental traditional medicine composed of crude herbal drugs and animal tissues is bitter and poorly water-soluble. To mask the bitterness of peonjahwan and enhance the release of bilirubin, one of the crude active ingredients of peonjahwan, peonja dry elixir (PDE), was prepared using a spray-dryer after extracting the crude materials in ethanol-water solution. Coated peonja dry elixir (CPDE) was then prepared by coating the PDE with Eudragit acrylic resin. Panel assessed bitterness and release test of bilirubin from PDE and CPDE were carried out and compared with peonjahwan alone. PDE was found to have little effect upon the reduction of the bitterness of peonjahwan. However, the bitterness of CPDE was found to reduce to 1/4 of that of peonjahwan due to the encapsulation of crude active ingredients by the dextrin and Eudragit shell (P<0.05). The release rate of bilirubin from PDE and CPDE for 60 min increased about 3.5- and 2.5- fold, respectively, compared to peonjahwan at pH 1.2. It is concluded that CPDE, which masked the bitterness of peonjahwan and enhanced the release of bilirubin, is a preferable delivery system for peonjahwan.

Bilirubin↗

PubMed2004

Associations between taste genetics, oral sensation and alcohol intake.

Alcohol produces a range of oral sensations, some of which have been shown to vary with the perceived bitterness of 6-n-propylthiouracil (PROP), one marker for genetic variation in taste. Some studies report that offspring of alcoholics are most likely to be PROP nontasters [Physiol. Behav. 51 (1992) 1261; Physiol. Behav. 64 (1998) 147], yet others report the offspring as more responsive to sodium chloride (NaCl) and citric acid, which appears to contradict the taste genetic hypothesis. We predicted alcohol sensation and intake from measures of taste genetics (PROP bitterness and number of fungiform papilla), NaCl and citric acid intensity, and spatial taste pattern in 40 females and 43 males. Subjects used the general Labeled Magnitude Scale (gLMS) [Chem. Senses 18 (1993) 683; J. Food Qual. Pref. 14 (2002) 125] as an intensity and hedonic scale. Those who tasted PROP as most bitter or had highest numbers of fungiform papilla reported greatest oral burn from an alcohol probe; those who tasted least PROP bitterness consumed alcoholic beverages most frequently. Although higher NaCl and citric acid ratings associated with more frequent consumption of alcoholic beverages, the findings could be explained by lower intensity of tastants on the tongue tip (chorda tympani nerve) relative to whole mouth perception. In multiple regression analyses, PROP bitterness and the spatial pattern of taste perception were independent contributors to the prediction of alcohol intake. In summary, the results support that variation in oral sensation associates with alcohol intake. Those who taste PROP as least bitter and have low chorda tympani relative to whole mouth taste intensity appear to have fewest oral sensory hindrances to the consumption of alcoholic beverages.

Adult↗

PubMed1998

Effects of artificial sweeteners on insulin release and cationic fluxes in rat pancreatic islets.

Beta-L-glucose pentaacetate, but not alpha-D-galactose pentaacetate, was recently reported to taste bitter and to stimulate insulin release. This finding led, in the present study, to the investigation of the effects of both bitter and non-bitter artificial sweeteners on insulin release and cationic fluxes in isolated rat pancreatic islets. Sodium saccharin (1.0-10.0 mM), sodium cyclamate (5.0-10.0 mM), stevioside (1.0 mM) and acesulfame-K (1.0-15.0 mM), all of which display a bitter taste, augmented insulin release from islets incubated in the presence of 7.0 mM D-glucose. In contrast, aspartame (1.0-10.0 mM), which is devoid of bitter taste, failed to affect insulin secretion. A positive secretory response to acesulfame-K was still observed when the extracellular K+ concentration was adjusted to the same value as that in control media. No major changes in 86Rb and 45Ca outflow from pre-labelled perifused islets could be attributed to the saccharin, cyclamic or acesulfame anions. It is proposed that the insulinotropic action of some artificial sweeteners and, possibly, that of selected hexose pentaacetate esters may require G-protein-coupled receptors similar to those operative in the recognition of bitter compounds by taste buds.

Animals↗

PubMed2002

Effect of the high-oleic trait on roasted peanut flavor in backcross-derived breeding lines.

The high-oleic trait of peanut (Arachis hypogaea L.) has been suggested to have a positive impact on the roasted peanut sensory attribute. A series of lines derived by backcrossing the high-oleic trait into several existing cultivars were compared with their parent cultivars at locations in Florida, Georgia, North Carolina, and Texas. Breeders grew their high-oleic lines and parents in three-replicate tests at one or two locations. The Florida high-oleic line F435-2-3-B-2-1-b4-B-B-3-b3-b3-1-B was grown at each location. The test included normal- and high-oleic variants of F435, GK 7, NC 7, NC 9, Sunrunner, Tamrun 96, and Tamspan 90. Sound-mature kernel samples were roasted, ground into paste, and evaluated by a sensory panel using a 14-point flavor intensity unit (fiu) scale. Background genotype had an effect (P < 0.01) on the heritable sensory attributes roasted peanut, sweet, and bitter. Oleate level had a positive effect on roasted peanut intensity, increasing it by 0.3 fiu averaged across all seven background genotypes. However, the magnitude of improvement varied across background genotypes. The high-oleic trait had no effect or increased the intensity of the roasted peanut attribute in each background genotype. The increase was greatest in Tamrun 96 (+0.6 fiu, P < 0.05) and Spanish genotypes Tamspan 90 (+0.4 fiu, P < 0.05) and F435 (+0.4 fiu, P < 0.10). A change of 0.5 fiu or more should be perceptible to consumers. Interaction between oleate level and background genotype was detected for sweet (P < 0.10) and bitter (P < 0.01) attributes. The trait had an increasing effect on the bitter attribute only in the background genotype of Tamspan 90 (+0.7 fiu, P < 0.01). There was a nonsignificant increase in bitterness in the other Spanish background genotype, F435. Changes in bitterness in runner- and Virginia-type backgrounds were close to zero. Incorporation of the high-oleic trait into peanut cultivars is likely to improve the intensity of the roasted peanut attribute, but it may also increase the bitter attribute in Spanish genotypes.

Arachis↗

PubMed1997

Taste responses to naringin, a flavonoid, and the acceptance of grapefruit juice are related to genetic sensitivity to 6-n-propylthiouracil.

Increased consumption of vegetables and fruit has long been the focus of dietary strategies for disease prevention. Some vegetables and fruit have bitter tastes, which can be aversive to consumers, particularly children. The present study tested the hypothesis that acceptance of grapefruit juice is influenced, in part, by sensitivity to the bitter taste of 6-n-propylthiouracil (Prop), a heritable trait. A sample of 123 women, mean age 28 y, was divided into nontasters (n = 39), tasters (n = 49), and supertasters (n = 35) of Prop by using procedures validated previously based on Prop detection thresholds and on intensity scaling of five suprathreshold solutions of Prop and sodium chloride. The subjects tasted and rated five solutions of the bioflavonoid naringin in 4% sucrose. Naringin, the principal bitter ingredient of grapefruit juice, has been implicated in the regulation of cytochrome P-450 enzymes. Increased taste acuity for both Prop and naringin was associated with greater dislike for each bitter compound. Prop supertasters disliked bitter naringin solutions significantly more than did either tasters or nontasters. Prop sensitivity was also associated with reduced acceptability of grapefruit juice. Acceptability of orange juice, which does not contain naringin, was unrelated to Prop taster status. Is the acceptability of other bitter vegetables and fruit also limited by inherited taste factors? If so, then genetic taste markers might limit dietary exposure to valuable dietary constituents and pose a barrier to current strategies for dietary change.

Adult↗

PubMed2004

Umami taste responses are mediated by alpha-transducin and alpha-gustducin.

The sense of taste comprises at least five distinct qualities: sweet, bitter, sour, salty, and umami, the taste of glutamate. For bitter, sweet, and umami compounds, taste signaling is initiated by binding of tastants to G-protein-coupled receptors in specialized epithelial cells located in the taste buds, leading to the activation of signal transduction cascades. Alpha-gustducin, a taste cell-expressed G-protein alpha subunit closely related to the alpha-transducins, is a key mediator of sweet and bitter tastes. Alpha-gustducin knock-out (KO) mice have greatly diminished, but not entirely abolished, responses to many bitter and sweet compounds. We set out to determine whether alpha-gustducin also mediates umami taste and whether rod alpha-transducin (alpha(t-rod)), which is also expressed in taste receptor cells, plays a role in any of the taste responses that remain in alpha-gustducin KO mice. Behavioral tests and taste nerve recordings of single and double KO mice lacking alpha-gustducin and/or alpha(t-rod) confirmed the involvement of alpha-gustducin in bitter (quinine and denatonium) and sweet (sucrose and SC45647) taste and demonstrated the involvement of alpha-gustducin in umami [monosodium glutamate (MSG), monopotassium glutamate (MPG), and inosine monophosphate (IMP)] taste as well. We found that alpha(t-rod) played no role in taste responses to the salty, bitter, and sweet compounds tested or to IMP but was involved in the umami taste of MSG and MPG. Umami detection involving alpha-gustducin and alpha(t-rod) occurs in anteriorly placed taste buds, however taste cells at the back of the tongue respond to umami compounds independently of these two G-protein subunits.

Animals↗

PubMed2004

Inhibition of P-glycoprotein activity and reversal of cancer multidrug resistance by Momordica charantia extract.

PURPOSE: Multidrug resistance (MDR) is known as a problem limiting the success of therapy in patients treated long term with chemotherapeutic drugs. The drug resistance is mainly due to the overexpression of the 170 kDa P-glycoprotein (Pgp), which causes a reduction in drug accumulation in the cancer cells. In this study, novel chemical modulator(s) from bitter melon (Momordica charantia L.) extracts obtained from leaves, fruits and tendrils were tested for their abilities to modulate the function of Pgp and the MDR phenotype in the multidrug-resistant human cervical carcinoma KB-V1 cells (high Pgp expression) in comparison with wildtype drug-sensitive KB-3-1 cells (lacking Pgp). METHODS: The KB-V1 and KB-3-1 cells were exposed to bitter melon extracts in the presence of various concentrations of vinblastine, and cytotoxicity was assessed by means of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. Relative resistance was calculated as the ratio of the IC50 value of the KB-V1 cells to the IC50 value of the KB-3-1 cells. Accumulation and efflux of vinblastine in KB-V1 and KB-3-1 cells were measured using a [3H]-vinblastine incorporation assay. RESULTS: The leaf extracts increased the intracellular accumulation of [3H]-vinblastine in KB-V1 cells in a dose-dependent manner, but extracts from the fruits and tendrils had no effect. By modulating Pgp-mediated vinblastine efflux, the leaf extracts decreased the [3H]-vinblastine efflux in KB-V1 cells in a dose-dependent manner, but not in KB-3-1 cells. Treatment of drug-resistant KB-V1 cells with bitter melon leaf extracts increased their sensitivity to vinblastine, but similar treatment of KB-3-1 cells showed no modulating effect. The fruit and tendril extracts did not affect the MDR phenotype in either cell line. CONCLUSION: The leaf extracts from bitter melon were able to reverse the MDR phenotype, which is consistent with an increase in intracellular accumulation of the drug. The exact nature of the active components of bitter melon leaf extracts remains to be identified.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1990

Effect of aloes on blood glucose levels in normal and alloxan diabetic mice.

The acute and chronic effects of the exudate of Aloe barbadensis leaves and its bitter principle were studied on plasma glucose levels of alloxan-diabetic mice. Aloes was administered orally, 500 mg/kg, and the bitter principle was administered intraperitoneally, 5 mg/kg. The hypoglycemic effect of a single oral dose of aloes on serum glucose level was insignificant whereas that of the bitter principle was very highly significant and extended over a period of 24 h with maximum hypoglycemia observed at +8 h. In chronic studies, aloes was administered twice daily and the bitter principle was administered once a day for 4 days. The maximum reduction in plasma glucose level was observed at the 5th day in both cases. The hypoglycemic effect of aloes and its bitter principle may be mediated through stimulating synthesis and/or release of insulin from the beta-cells of Langerhans.

Administration, Oral↗

PubMed2005

[Gustatory perceptions in children].

As soon as the end of gestation, the gustatory system is stimulated by the taste-active compounds carried by the amniotic fluid and its maturation continues until mid-childhood. Facial expressions and relative ingestion methods show that the newborn can discriminate the various taste qualities (bitter, salty, sour, sweet and umami). The range of individual responses is wide. Neonatal reactions to sweet and umami are generally considered to express pleasure. The bitter and sour stimulations lead to hedonically negative reactions. The response to salt taste is less characteristic. Overall, the attraction towards sweet and the rejection of bitter and sour tastes become more pronounced during childhood but tend to decrease in adult life. The early attraction to sweetness is reinforced by exposure to sweet stimulations. With age, the response to salt evolves towards attraction which intensity is dependent on the context and on postnatal exposures to salt. The link between gustatory sensitivity to sweet, salty and sour stimuli and food preferences is far from being clear; the sensitivity to bitter taste better explains the rejection of bitter foods, such as vegetables for instance. The development of gustatory perceptions partly depends upon experience. A better knowledge of the role of experience could help to improve the orientation and the efficacy of nutritionally-oriented food education strategies.

Adolescent↗

PubMed2005

Peripheral gustatory processing of sweet stimuli by golden hamsters.

Behaviors and taste-nerve responses to bitter stimuli are linked to compounds that bind T2 receptors expressed in one subset of taste-bud receptor cells (TRCs); and behavioral and neural responses to sweet stimuli are linked to chemical compounds that bind a T1 receptor expressed in a different TRC subset. Neural and behavioral responses to bitter-sweet mixtures, however, complicate the ostensible bitter and sweet labeled lines. In the golden hamster, Mesocricetus auratus, quinine hydrochloride, the bitter prototype, suppresses chorda tympani (CT) nerve responses to the sweet prototype: sucrose. This bitter-sweet inhibition was tested with concentration series of sucrose and dulcin, a hydrophobic synthetic sweetener that hamsters behaviorally cross-generalize with sucrose. Dulcin, sucrose and other sweeteners activate one subset of CT fibers: S neurons; whereas, quinine activates a separate subset of CT fibers: E neurons. Whole-nerve and S-neuron CT responses to a sweetener concentration series, mixed with 0, 1, 3 and 10 mM quinine, were measured for 0-2.5 s transient and/or 2.6-10 s steady-state response periods. Ten-sec total single-fiber records, aligned at response onset, were averaged for 100 ms bins to identify response oscillations. Quinine inhibition of dulcin and sucrose responses was identical. Each log molar increment in quinine resulted in equivalent declines in response to either sweetener. Furthermore, sucrose response decrements paralleled response increments in quinine-sensitive CT neurons to the same quinine increases. A 1.43 Hz bursting rhythm to the sweeteners was unchanged by quinine inhibition or decreases in sweetener concentration. Taste-bud processing, possibly between-cell inhibition and within-cell negative feedback, must modify signals initiated by T1 receptors before they are transmitted to the brain.

Action Potentials↗

PubMed2006

Facial and affective reactions to tastes and their modulation by sadness and joy.

This study examined adults' affective and facial reactions to tastes which differ in quality and valence, and the impact of sadness and joy on these reactions. Thirty-six male and female subjects participated voluntarily. Subjects each tasted 6 ml of a sweet chocolate drink, a bitter quinine solution (0.0015 M) and a bitter-sweet soft drink. Following a baseline period, either joy or sadness was induced using film clips before the same taste stimuli were presented for a second time. Subjects rated the drinks' pleasantness and intensity of taste immediately after each stimulus presentation. Facial reactions were videotaped and analysed using the Facial Action Coding System (FACS [P. Ekman, W.V. Friesen, Facial Action Coding System: Manual. Palo Alto, CA: Consulting Psychologists Press; 1978., P. Ekman, W. Friesen, J. Hager, Facial Action Coding System. Salt Lake City, Utah: Research Nexus; 2002.]). The results strongly indicated that the tastes produced specific facial reactions that bear strong similarities to the facial reactivity patterns found in human newborns. The data also suggest that some adults' facial reactions serve additional communicative functions. Emotions modulated taste ratings, but not facial reactions to tastes. In particular, ratings of the sweet stimulus were modulated in congruence with emotion quality, such that joy increased and sadness decreased the pleasantness and sweetness of the sweet stimulus. No emotion-congruent modulation was found for the pleasantness and intensity ratings of the bitter or the bitter-sweet stimulus. This 'robustness' of bitter taste ratings may reflect a biologically meaningful mechanism.

Adult↗