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Query: UMLS:C0235290 (bitter taste)
 1,408 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The appearance of undesirable bitter taste in Ragusano cheese was investigated by comparing the composition of 9 bitter cheeses with that of 9 reference cheeses of good quality by means of chemical, electrophoretic, and chromatographic analyses. Rates of proteolysis were significantly affected in cheeses of different quality. Primary proteolysis, as measured by pH 4.6-soluble N, was significantly greater in bitter cheeses compared with reference samples. Urea-PAGE profiles showed an almost complete breakdown of caseins in bitter cheeses and the further degradation of primary peptides into smaller compounds not detectable by this technique. Cheeses with defects had significantly lower levels of secondary proteolysis as reflected by the percentage of pH 4.6-soluble N soluble in 12% trichloroacetic acid and the amounts of total free amino acids. Peptides separated by reversed phase-HPLC revealed that the large and significant differences in peptide profiles of the soluble fractions between bitter and reference cheeses were mainly due to a much higher proportion of hydrophobic peptides in the former. The occurrence of bitterness in Ragusano cheese was therefore attributable to unbalanced levels of proteolysis and peptidolysis. Extensive degradation of caseins and primary peptides by activities of proteases produced large amounts of small- and medium-sized hydrophobic peptides that were not adequately removed by peptidases of microflora and therefore accumulated in cheese potentially contributing to its bitter taste. The presence of these compounds in bitter cheeses was related to high salt-in-moisture and low moisture contents that limited the enzymatic activities of microflora important in secondary proteolysis. Combining salt-in-moisture and the ratio of hydrophobic-to-hydrophilic soluble peptides resulted in the best logistic partial least squares regression model predicting cheese quality. Although bitterness is known to be rarely encountered in cheese at salt-in-moisture levels >5.0, all of the bitter cheeses analyzed in this study had salt-in-moisture levels much greater than this value. According to the logistic model, a risk of bitterness development may exist for cheeses with a midrange (5 to 10%) salt-in-moisture content but with an inadequate level of secondary proteolysis.
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PMID:Evaluation of bitterness in Ragusano cheese. 1577 96

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.
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PMID:[Gustatory perceptions in children]. 1588 51

Products made from Herba Santa (Eriodictyon californicum (H. & A.) Torr.) have been used as bitter remedies for some pharmaceutical applications for many years, but they are actually too aromatic to be useful for many food or pharmaceutical applications. In sensory studies flavanones homoeriodictyol (1), its sodium salt (1-Na), sterubin (2), and eriodictyol (4) could significantly decrease the bitter taste of caffeine without exhibiting intrinsic strong flavors or taste characteristics. Further investigations on 1-Na elicited a broad masking activity between 10 and 40% toward different chemical classes of bitter molecules (e.g. salicin, amarogentin, paracetamol, quinine) but not toward bitter linoleic acid emulsions. For caffeine and amarogentin, dose-response studies were performed; the masking activity toward bitter taste for both compounds reached a plateau at higher concentrations of 1-Na. Due to these facts, homoeriodictyol sodium salt (1-Na) seems to be a very interesting new taste modifier for food applications and pharmaceuticals.
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PMID:Evaluation of bitter masking flavanones from Herba Santa (Eriodictyon californicum (H. and A.) Torr., Hydrophyllaceae). 1602 96

Activity-directed fractionation of heated carbohydrate/alanine solutions recently led to the discovery of (+)-(S)-1-(1-carboxyethyl)-5-hydroxy-2-(hydroxymethyl)pyridinium inner salt (1, alapyridaine), and it has been shown that this compound lowers the detection thresholds of sugars, glutamate, and NaCl solutions, whereas no influence on bitter perception was observed. As this class of Maillard-derived pyridinium betaines seemed to be promising targets for further research on their taste modulatory activity, the objective of the present investigation was to screen for bitter taste-suppressing target molecules in combinatorial libraries of pyridinium betaines prepared from 5-(hydroxymethyl)furan-2-aldehyde and amino acid mixtures by use of Maillard-type reaction chemistry instead of synthesizing and purifying each derivative individually. By application of hydrophilic interaction liquid chromatography in combination with the recently developed comparative taste dilution analysis, followed by structure determination, synthesis, and sensory studies, we have now succeeded in identifying 1-carboxymethyl-5-hydroxy-2-hydroxymethylpyridinium inner salt (2) as a potential bitter-suppressing candidate. While tasteless on its own, 2 was found to reduce the bitterness of various bitter tastants such as the amino acid L-phenylalanine, the peptide Gly-Leu, the alkaloid caffeine, and the bitter glycosides salicin and naringin.
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PMID:Application of hydrophilic interaction liquid chromatography/comparative taste dilution analysis for identification of a bitter inhibitor by a combinatorial approach based on Maillard reaction chemistry. 1627 18

We combined behavioural and electrophysiological experiments to study whether bitter taste is perceived at the antennal level in honeybees, Apis mellifera. Our behavioural studies showed that neither quinine nor salicin delivered at one antenna at different concentrations induced a retraction of the proboscis once it was extended in response to 1 M sucrose solution delivered to the opposite antenna. Bees that extended massively their proboscis to 1 M sucrose responded only partially when stimulated with a mixture of 1 M sucrose and 100 mM quinine. The mixture of 1 m sucrose and 100 mM salicin had no such suppressive effect. No behavioural suppression was found for mixtures of salt solution and either bitter substance. Electrophysiological recordings of taste sensillae at the antennal tip revealed sensillae that responded specifically either to sucrose or salt solutions, but none responded to the bitter substances quinine and salicin at the different concentrations tested. The electrophysiological responses of sensillae to 15 mM sucrose solution were inhibited by a mixture of 15 mM sucrose and 0.1 mM quinine, but not by a mixture of 15 mM sucrose and 0.1 mM salicin. The responses of sensillae to 50 mM NaCl were reduced by a mixture of 50 mm NaCl and 1 mM quinine but not by a mixture of 50 mM NaCl and 1 mM salicin. We concluded that no receptor cells for the bitter substances tested, exist at the level of the antennal tip of the honeybee and that antennal bitter taste is not represented as a separate perceptual quality.
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PMID:Electrophysiological and behavioural characterization of gustatory responses to antennal 'bitter' taste in honeybees. 1636 82

Fifty lactobacilli isolated from black table olive brines were evaluated for their salt tolerance, resistance to oleuropein and verbascoside, and ability to grow in modified filter-sterilized brines. A strain of Lactobacillus pentosus was selected and used as a starter to ferment, in pilot plant, black olives (Itrana and Leccino cv.) in brines modified for pH, carbohydrate, and growth factor concentrations, at 28 degrees C. The temperature-controlled fermentation of Leccino cv. olives resulted in obtaining ready-to-eat, high-quality table olives in a reduced-time process. HPLC analysis of phenolic compounds from fermented olives showed a decrease of oleuropein, a glucoside secoiridoid responsible for the bitter taste of olive drupes, and an increase of the hydroxytyrosol concentration. The selected strain of L. pentosus (1MO) allowed the reduction of the debittering phase period to 8 days.
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PMID:The use of Lactobacillus pentosus 1MO to shorten the debittering process time of black table olives (Cv. Itrana and Leccino): a pilot-scale application. 1671 8

The free fatty acids (FFAs), linoleic and oleic acids, commonly found in dietary fats can be detected by rats on the basis of gustatory cues following conditioned taste aversion pairings. FFAs depolarize the membrane potential of isolated rat taste receptor cells by inhibiting delayed rectifying potassium channels. This study examined the licking response of rats to sweet, salt, sour, and bitter taste solutions when 88 muM linoleic acid, 88 muM oleic acid, or an 88 muM linoleic-oleic acid mixture was added to the solutions. The presence of linoleic, oleic, and the linoleic-oleic acid mixture in sweet solutions produced increases in the licking responses, whereas adding linoleic, oleic, and the linoleic-oleic acid mixture to salt, sour, or bitter taste solutions produced decreases in licking responses when compared with the licking responses to the solutions in the absence of the FFAs. We conclude that FFAs may act in the oral cavity to depolarize taste receptor cells and therefore to increase the perceived intensity of concomitant tastants, thus contributing to the enhanced palatability associated with foods containing high dietary fat.
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PMID:Linoleic and oleic acids alter the licking responses to sweet, salt, sour, and bitter tastants in rats. 1692 77

Circumstances in which serotonin (5-HT) and noradrenaline (NA) are altered, such as in anxiety or depression, are associated with taste disturbances, indicating the importance of these transmitters in the determination of taste thresholds in health and disease. In this study, we show for the first time that human taste thresholds are plastic and are lowered by modulation of systemic monoamines. Measurement of taste function in healthy humans before and after a 5-HT reuptake inhibitor, NA reuptake inhibitor, or placebo showed that enhancing 5-HT significantly reduced the sucrose taste threshold by 27% and the quinine taste threshold by 53%. In contrast, enhancing NA significantly reduced bitter taste threshold by 39% and sour threshold by 22%. In addition, the anxiety level was positively correlated with bitter and salt taste thresholds. We show that 5-HT and NA participate in setting taste thresholds, that human taste in normal healthy subjects is plastic, and that modulation of these neurotransmitters has distinct effects on different taste modalities. We present a model to explain these findings. In addition, we show that the general anxiety level is directly related to taste perception, suggesting that altered taste and appetite seen in affective disorders may reflect an actual change in the gustatory system.
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PMID:Human taste thresholds are modulated by serotonin and noradrenaline. 1715 Dec 69

Taste acuity declines with age and may be dependent upon Zn status. The aim of the present double-blind, randomised controlled intervention trial has been to determine taste acuity in response to Zn supplementation (placebo, or 15 or 30 mg Zn/d). Healthy older European adults aged 70-87 years were recruited within Italy (Rome) (n 108) and France (Grenoble) (n 91) to the European Commission-funded Zenith project. A signal detection theory approach was adopted for taste assessment. The data were converted to R indices and analysed by repeated-measures ANOVA controlling for baseline taste acuity as well as serum and erythrocyte Zn. Serum Zn increased post-intervention, indicating compliance with the intervention. Results differed across geographical region. Salt taste acuity was greater in response to Zn (30 mg) than placebo post-intervention among those recruited in Grenoble. There was no apparent change in acuity for sweet, sour or bitter taste in response to Zn. Supplemented Zn may have potential to enhance salt taste acuity in those over the age of 70 years. Further research is required to determine if enhanced salt taste acuity is reflected in the eating experiences of older individuals.
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PMID:Taste acuity in response to zinc supplementation in older Europeans. 1765 17

Chlorhexidine (CHX) gluconate, a bitter bis-biguanide antiseptic, reduces the intensity of the salty taste of NaCl and bitter taste of quinine in humans. This study addresses regional specificity of CHX's effects on taste. Perceptual intensity and quality were measured for separate taste bud containing oral loci innervated either by afferent fibers of cranial nerve (CN) VII or CN IX. Measurements were obtained following three 1-min oral rinses with either 1.34 mM CHX or water, the control rinse. CHX rinse reduced the intensity of NaCl more at the tongue tip and palate than at posterior oral sites. Thus, fungiform and palatal salt-taste receptors may differ from salt-taste receptors of the foliate and circumvallate taste papillae. The intensity of quinine.HCl was reduced equally by CHX at all sites tested but was frequently tasteless on the less sensitive anterior sites, suggesting quinine receptor diversity. In rodents, a portion of NaCl-taste receptors in the receptive field of CN VII is sensitive to the epithelial Na+ channel blocker amiloride and a portion is amiloride insensitive; all CN IX receptors are amiloride insensitive. The current results are the first to suggest that there may also be distinct, regionally specific populations of NaCl-taste receptors in humans.
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PMID:Regional specificity of chlorhexidine effects on taste perception. 1826 92


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