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At least 307 records · Page 17Linked to original sources

PubMed2005

Sensory-guided decomposition of roasted cocoa nibs (Theobroma cacao) and structure determination of taste-active polyphenols.

Sequential application of solvent extraction, gel permeation chromatography, and RP-HPLC in combination with taste dilution analyses, followed by LC-MS and 1D/2D-NMR experiments and thiolytic degradation, revealed that, besides theobromine and caffeine, the flavan-3-ols epicatechin, catechin, procyanidin B-2, procyanidin B-5, procyanidin C-1, [epicatechin-(4beta-->8)](3)-epicatechin, and [epicatechin-(4beta-->8)](4)-epicatechin were among the key compounds contributing to the bitter taste as well as the astringent mouthfeel imparted upon consumption of roasted cocoa. In addition, a series of quercetin, naringenin, luteolin, and apigenin glycopyranosides as well as a family of not previously identified amino acid amides, namely, (+)-N-[4'-hydroxy-(E)-cinnamoyl]-L-aspartic acid, (+)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-aspartic acid, (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-glutamic acid, (-)-N-[4'-hydroxy-(E)-cinnamoyl]-L-glutamic acid, (-)-N-[4'-hydroxy-(E)-cinnamoyl]-3-hydroxy-L-tyrosine, (+)-N-[4'-hydroxy-3'-methoxy-(E)-cinnamoyl]-L-aspartic acid, and (+)-N-(E)-cinnamoyl-L-aspartic acid, have been identified as key astringent compounds of roasted cocoa. Furthermore, (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-3-hydroxy-l-tyrosine (clovamide), (-)-N-[4'-hydroxy-(E)-cinnamoyl]-L-tyrosine (deoxyclovamide), and (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tyrosine, reported previously as antioxidants, have been found as contributors of cocoa's astringent taste. By means of the half-tongue test, the taste thresholds of flavan-3-ols and glycosides have been determined.

Adult↗

PubMed2002

Taste disturbance after tonsillectomy.

Of the 3583 outpatients treated at our taste disorder clinic over a period of 15 years, 11 (0.31%) complained of taste disorder after tonsillectomy. The cause of taste disorder was identified in 8 of the 11 cases: in 3 cases it was caused by direct or indirect damage to the lingual branch of the glossopharyngeal nerve; in 2 cases it was attributable to medication taken by the patient after tonsillectomy; and in 3 cases taste disturbance was caused by a lack of dietary zinc, even though this was identified at the time of tonsillectomy. These findings indicate the importance of (i) informing patients when consent for tonsillectomy is obtained that there is a risk of postoperative taste disorder; (ii) measuring the patient's taste threshold and serum zinc level preoperatively; and (iii) obtaining a thorough drug history, including details of non-prescription medications habitually taken by the patient.

Adult↗

PubMed2006

[Bilateral gustatory disturbance associated with left putaminal hemorrhage].

We reported a 39-year-old, left-handed man with sudden onset hypogeusia. Taste threshold examined by a filter-paper disc method was elevated remarkably on both sides of the tongue. Additionally, the patient showed mild right central facial nerve palsy and mild weakness in the right upper limb. Brain CT showed left putaminal hemorrhage. Brain MRI demonstrated a hemorrhage in the left putamen and edema affecting the insular cortex. In this case, the gustatory information from both sides of the tongue, regardless of whether the nerves cross in a brainstem, is suggested to project to the left insular cortex before ascending to the higher order taste and language areas.

Adult↗

PubMed1988

Liposomes as model for taste cells: receptor sites for bitter substances including N-C=S substances and mechanism of membrane potential changes.

Various bitter substances were found to depolarize liposomes. The results obtained are as follows: (1) Changes in the membrane potential of azolectin liposomes in response to various bitter substances were monitored by measuring changes in the fluorescence intensity of 3,3'-dipropylthiocarbocyanine iodide [diS-C3(5)]. All the bitter substances examined increased the fluorescence intensity of the liposome-dye suspension, which indicates that the substances depolarize the liposomes. There existed a good correlation between the minimum concentrations of the bitter substances to depolarize the liposomes and the taste thresholds in humans. (2) The effects of changed lipid composition of liposomes on the responses to various bitter substances vary greatly among bitter substances, suggesting that the receptor sites for bitter substances are multiple. The responses to N-C=S substances and sucrose octaacetate especially greatly depended on the lipid composition; these compounds depolarized only liposomes having certain lipid composition, while no or hyperpolarizing responses to these compounds were observed in other liposomes examined. This suggested that the difference in "taster" and "nontaster" for these substances can be explained in terms of difference in the lipid composition of taste receptor membranes. (3) It was confirmed that the membrane potential of the planar lipid bilayer is changed in response to bitter substances. The membrane potential changes in the planar lipid bilayer as well as in liposomes in response to the bitter substances occurred under the condition that there is no ion gradient across the membranes. These results suggested that the membrane potential changes in response to bitter substances stem from the phase boundary potential changes induced by adsorption of the substances on the hydrophobic region of the membranes.

Benzothiazoles↗

PubMed1985

Canadian medical experiments on Shuttle flight 41-G.

During the 41-G mission, two payload specialist astronauts took part in six Canadian medical experiments designed to measure how the human nervous system adapts to weightlessness, and how this might contribute to space motion sickness. Similar tests conducted pre-flight provided base-line data, and post-flight experiments examined re-adaptation to the ground. No changes were detected in the vestibulo-ocular reflex during this 8-day mission. Pronounced proprioceptive illusions were experienced, especially immediately post-flight. Tactile acuity was normal in the fingers and toes, but the ability to judge limb position was degraded. Estimates of the locations of familiar targets were grossly distorted in the absence of vision. There were no differences in taste thresholds or olfaction. Despite pre-flight tests showing unusual susceptibility to motion sickness, the Canadian payload specialist turned out to be less susceptible than normal on-orbit. Re-adaptation to the normal gravity environment occurred within the first day after landing.

Adaptation, Physiological↗

PubMed1998

Production of fermented milk using a malty compound-producing strain of Lactococcus lactis subsp. lactis biovar. diacetylactis, isolated from Zimbabwean naturally fermented milk.

Malty compound-producing Lactococcus lactis subsp. lactis biovar. diacetylactis strain INF-DM1, originally isolated from naturally fermented milk in Zimbabwe was used to prepare fermented milk from ordinary milk, milk enriched with 2.5% (w/v) skimmed milk powder and by 2.5% (w/v) increase in dry matter by ultrafiltration. Inoculated milk was incubated at 22, 30 and 37 degrees C. Analyses were made after 0, 9, 18 and 24 h incubation and also after 24 h incubation followed by storage for one week at 4 degrees C. Samples were analysed for volatile compounds including malty compounds and for organic acids, pH and log cfu/g. All samples were also judged for sensory attributes. Products made from enriched milks showed increased viscosity which was most marked in ultrafiltrated milk incubated at 30 and 37 degrees C. The levels of certain compounds (lactic acid, citrate and diacetyl) were significantly affected by milk type. Incubation temperature had a significant effect on starter growth rate and the rate of production and amount of the malty compounds, lactate, diacetyl, ethanol, acetoin and acetaldehyde. 3-Methyl butanal concentrations were above the taste threshold level of 0.06 ppm in almost all products, including stored products. Although initial growth rate was fastest at 37 degrees C, an uncoupling of acid production and growth was observed after 9 h incubation, suggesting that this is above the optimum temperature for this strain. In addition, products incubated at 37 degrees C showed a tendency to whey separation, indicating that this temperature is also too high to give optimum product quality. All products attained good scores in sensory analysis provided that fermentation was complete. Variation in the levels of malty compounds during the fermentation had no significant effect on the sensory score for total flavour.

Acetaldehyde↗

PubMed2002

[Gustatory disturbance associated with putaminal hemorrhage].

48-year-old left-handed man experienced a sudden loss of taste, followed by dysarthria and dysphagia. Taste threshold examined by a small filter-paper disc method was severely elevated on both sides of the tongue. Brain CT revealed right putaminal hemorrhage that measured 9.3 ml in volume. In addition, brain MRI showed multiple cerebral infarcts bilaterally in the basal ganglia, and the corona radiata, and on the right side of the middle pontine tegmentum. His dysarthria and dysphagia seemed to be caused by interruption of bilateral cortico-bulbar tracts, and resolved within two weeks when edema around the hemorrhage regressed. The gustatory disturbance that persisted may be caused by the interruption of central gustatory pathways at the pons on one side, and subcortically close to the insular cortex on the other side.

Cerebral Infarction↗

PubMed2001

Characterization of natural "cooling" compounds formed from glucose and l-proline in dark malt by application of taste dilution analysis.

Gel permeation chromatography of the solvent extractables isolated from a thermally treated glucose/L-proline mixture and sensory analysis of the fractions collected led to the discovery of the presence of "cooling" compounds in Maillard reactions. To characterize the key compounds imparting this cooling sensation to the oral cavity, a taste dilution analysis was performed by determining the taste threshold of reaction products in serial dilutions of HPLC fractions to select the most intense "cooling" compounds in the complex GPC fraction of the Maillard reaction mixture. Systematic (13)C-labeling experiments and GC-MS, LC-MS, and 1D- and 2D-NMR measurements, followed by synthesis, led to the unequivocal identification of 3-methyl-2-(1-pyrrolidinyl)-2-cyclopenten-1-one (3-MPC), 5-methyl-2-(1-pyrrolidinyl)-2-cyclopenten-1-one (5-MPC), and 2,5-dimethyl-4-(1-pyrrolidinyl)-3(2H)-furanone (DMPF) as the key compounds contributing the most to the cooling sensation. Although these structures were described earlier with regard to Maillard reactions, this is the first time that Maillard reaction products are reported to cause intense cooling sensations by degustation. Finally, the detection of 5-MPC (101.3 microg/kg), 3-MPC (9.4 microg/kg), and DMPF (11.5 microg/kg) in dark malt verified their natural occurrence in thermally processed foods.

Chromatography, Gas↗

PubMed1969

An electrophysiological analysis of the action of carbohydrates on the sugar receptor of the blowfly.

Measurements of the taste thresholds of blowflies for a wide variety of carbohydrates, presented individually and in combination, showed that the stimulating effects of the compounds are not always additive. Both synergism and inhibition were observed. In order to gain some insight into the nature of the molecular events occurring in the receptor, it was deemed necessary to investigate synergism and inhibition in single receptors by electrophysiological methods. This investigation revealed that mannose enhances the responses of the sugar receptor of the blowfly to aldose and aldose-derived sugars and reduces responses to the ketose sugars. Responses to fructose are enhanced by the presence of glucose and reduced by the addition of sorbose. Curves describing responses to the aldose and aldose-derived sugars over a wide range of concentrations have steep slopes and intersect the x axis at high concentration values. Curves relating to the ketoses have shallow slopes and lower intercepts. Two or more modes of action of carbohydrates on the sugar receptor are suggested by these data.

Animals↗

PubMed1993

Color as a factor in food choice.

From birth, nature teaches us to make judgements on our environment based in large measure on color. As such, it plays a key role in food choice by influencing taste thresholds, sweetness perception, food preference, pleasantness, and acceptability. Its role is elusive and difficult to quantify, however, which at times has placed color in a secondary role to the other sensory characteristics, a position not entirely consistent with the facts. Color, in a quantitative sense, has been shown to be able to replace sugar and still maintain sweetness perception in flavored foods. It interferes with judgments of flavor intensity and identification and in so doing has been shown to dramatically influence the pleasantness and acceptability of foods. Studies in the literature have used cross-sectional population panels to study these effects, but a recent investigation of color-sensory interactions in beverages has compared the response of a college age group with the response of a panel consisting of a more mature population. Interestingly, the older group showed significant differences from the college age group in their response to the effects of color on several sensory parameters as well as showing a direct correlation between beverage consumption and color. Color is often taken for granted, but this position must be reevaluated in view of such studies and the need to create more appealing foods for different segments of our society.

Carbohydrates↗

PubMed1982

Population genetic models in the study of aging and longevity in a Mennonite community.

This is a preliminary report on a 3-year multidisciplinary study of aging among historically and genetically related Mennonite congregations in Kansas and Nebraska. Three aspects of longevity and aging are examined: (1) the relationship of heterozygosity to survivorship using 8 genetic blood group loci, (2) changes in taste sensitivity with age using 14 dilutions of PTC; and (3) life span correlations among parents and offspring during a 100 year period. Heterozygosity was found to be independent of survivorship. No diminution in taste sensitivity to PTC was found with increasing age although a significant difference in PTC taste thresholds was found between males and females. No relationship was found between nontasters and individuals with a history of thyroid disease. Mother's life span was found to correlate more closely with daughter than any other familial correlation.

Adolescent↗

PubMed2005

Determination of trace concentrations of bromophenols in water using purge-and-trap after in situ acetylation.

An analytical method that enables detection and quantification of bromophenols (BPs) at taste threshold concentrations (2,6-DBP: 0.5 ng/L) was developed. This method involves conversion of the BPs to their acetates, followed by isolation of the acetates by a modified purge-and-trap procedure, and analysis by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. Bromophenyl acetates were synthesized so that each of the two steps in the method could be developed and optimised in isolation to the other. Deuterated BPs (phenol-d5, 2-BP-d4, 4-BP-d2, 2,6-DBP-d3, 2,4-DBP-d3 and 2,4,6-TBP-d2) were synthesized to enable quantification of analytes using the deuterated analogues of analytes as internal standards. This method allowed quantification of BPs at concentrations ranging from the detection limits (3 ng/L for phenol and 0.1-0.5 ng/L for each of the BPs) to 1000 ng/L for each analyte, with repeatabilities of < or =14% (RSD) for concentrations of 1 ng/L and < or =9% (RSD) for concentrations of 10-1000 ng/L, with recoveries ranging from 91 to 97%.

Acetylation↗

PubMed2005

Identification of metallic-smelling 1-octen-3-one and 1-nonen-3-one from solutions of ferrous sulfate.

Taste threshold tests of ferrous sulfate (FeSO4) solutions have been confounded by the presence of putative odorants. To detect the presence of odorants released from these solutions solid-phase microextraction (SPME) was used to collect volatiles in the headspace above FeSO4 solutions. Gas chromatography-olfactometry of samples collected over three time periods (1, 5, and 16 h) and at two temperatures (22 and 37 degrees C) revealed the presence of several metallic-smelling odorants in the headspace. Using authentic standards, two of the odorants were conclusively identified as 1-octen-3-one and 1-nonen-3-one. Trace levels of other odorants were also detected, but dilution experiments indicated that 1-nonen-3-one was at least 10 times more potent than anything else released from the solutions. 1-Octen-3-one and 1-nonen-3-one are excellent candidates for the metallic odor responses often observed in threshold testing of solutions of FeSO4.

Chromatography, Gas↗

PubMed1999

A kinetic study on benzoic acid pungency and sensory attributes of benzoic acid.

Aqueous solutions of benzoic acid (BA) were evaluated by two methods: (i) sensory profile: a descriptive test of sensory attributes combined with semiquantitative analysis; and (ii) pungency intensity measures as a function of time: a computerized recording using specific software. Kinetic parameters evaluated were maximal intensity (I(MAX)), total time of pungency (Ttot), rates of increase (V1) and decrease (V2), half-life (T1/2), area under curve (AUC) and time to maximal intensity (T(IMAX)). Results were analyzed by ANOVA, LSD test, iterative calculations and adjustment to equations according to mathematical models, regression analysis, principal component analysis (PCA) and clusters analysis. Pungency was the main sensory attribute of BA (3-36 mM) in the tongue and epiglottis. The seven kinetic parameters showed concentration-dependency (P < 0.001) and were described by different functions: (i) lineal: I(MAX) = 2.24 +/- 0.14C - 3.06 +/- 2.58, R2 = 0.98; T(IMAX) = 0.19 +/- 0.02C + 6.87 +/- 0.47, R2 = 0.92; V1 = 0.68 +/- 0.03C + 0.10 +/- 0.69, R2 = 0.99; AUC = 49.10 +/- 3.17C - 230.78 +/- 59.66, R2 = 0.98; (ii) potency: T1/2 = 6.62 +/- 0.61C(0.39+/-0.03), R2 = 0.97; V2 = 1.07 +/- 0.11C(0.53+/-0.04), R2 = 0.98; Ttot = 8.08 +/- 1.01C(0.43+/-0.04), R2 = 0.96. PCA revealed high correlation between (i) T(IMAX) and Ttot; (ii) T1/2 and V2; and (iii) I(MAX) and V1. Stimuli grouped across three main clusters: (i) 3 and 6 mM; (ii) 9, 12 and 18 mM; and (iii) 24 and 36 mM. Maximal pungency intensity best correlated with both concentration and persistence among kinetic parameters. Prototypical prickling of BA was observed at 12 and 18 mM.

Adult↗

PubMed1986

Design and analysis considerations for a longitudinal study of periodontal disease.

Perception and concern for the health changes in our aging population led the Veterans Administration to initiate an interdisciplinary and longitudinal investigation of the aging process, the Veterans Administration Normative Aging Study, in 1963. A cohort of the 2,280 healthy men of this study self-selected to enroll in the dental longitudinal study, an investigation of oral health in these healthy males. In 1968, 1,221 men between the ages of 25 and 75 began with a baseline cycle of 5 general series of examinations, including an interim health history and survey of dietary habits; masticatory performance and taste thresholds; salivary analyses; oral cytologic and radiographic survey and comprehensive clinical data on caries and periodontal status. Design considerations for the Dental Longitudinal Study included prospective planning of specific oral variables to be recorded, and provision of collection techniques to allow for additional analyses based on a wide menu of retrospective data. The volunteer cohort was screened to obtain men who met stringent general health criteria, who represented wide socioeconomic ranges and would likely remain geographically stable. Importantly, enrollment in the parent study was without regard for dental status or oral health. Administrative design considerations included orderly transfer for exam data to machine-readable format by use of optical scan forms designed to register specific oral variables, with security preserved for the primary source records and rapid record retrieval. Additional data collection requiring manual coding was designed to transfer spreadsheets of clinical impressions and diagnoses to computer retrieval protocols. Provisions for recording of exceptional circumstances, i.e., salient oral pathology, were recognized and the optical scan forms modified to index and retrieve such cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2003

Positional cloning of the human quantitative trait locus underlying taste sensitivity to phenylthiocarbamide.

The ability to taste the substance phenylthiocarbamide (PTC) has been widely used for genetic and anthropological studies, but genetic studies have produced conflicting results and demonstrated complex inheritance for this trait. We have identified a small region on chromosome 7q that shows strong linkage disequilibrium between single-nucleotide polymorphism (SNP) markers and PTC taste sensitivity in unrelated subjects. This region contains a single gene that encodes a member of the TAS2R bitter taste receptor family. We identified three coding SNPs giving rise to five haplotypes in this gene worldwide. These haplotypes completely explain the bimodal distribution of PTC taste sensitivity, thus accounting for the inheritance of the classically defined taste insensitivity and for 55 to 85% of the variance in PTC sensitivity. Distinct phenotypes were associated with specific haplotypes, which demonstrates that this gene has a direct influence on PTC taste sensitivity and that sequence variants at different sites interact with each other within the encoded gene product.

Alleles↗

PubMed1991

Chromosomal Integration and Expression of Two Bacterial alpha-Acetolactate Decarboxylase Genes in Brewer's Yeast.

A bacterial gene encoding alpha-acetolactate decarboxylase, isolated from Klebsiella terrigena or Enterobacter aerogenes, was expressed in brewer's yeast. The genes were expressed under either the yeast phosphoglycerokinase (PGK1) or the alcohol dehydrogenase (ADH1) promoter and were integrated by gene replacement by using cotransformation into the PGK1 or ADH1 locus, respectively, of a brewer's yeast. The expression level of the alpha-acetolactate decarboxylase gene of the PGK1 integrant strains was higher than that of the ADH1 integrants. Under pilot-scale brewing conditions, the alpha-acetolactate decarboxylase activity of the PGK1 integrant strains was sufficient to reduce the formation of diacetyl below the taste threshold value, and no lagering was needed. The brewing properties of the recombinant yeast strains were otherwise unaltered, and the quality (most importantly, the flavor) of the trial beers produced was as good as that of the control beer.

Journal Article↗

PubMed1984

Salivary clearance of sugar and its effects on pH changes by Streptococcus mitior in an artificial mouth.

We recently developed a computer model of oral sugar clearance (Dawes, 1983), and an artificial mouth has now been constructed which will allow variation in the salivary parameters identified in the model and the study of their effects on bacterial acid production. Using a thin layer of S. mitior, strain 572, over a miniature Sb electrode to measure bacterial pH changes during sugar clearance from the "mouth", we found that three consecutive sets of "Stephan curves" could be obtained with the same bacteria during one day. In each of several experimental series, one salivary parameter was varied, while other parameters were held constant. The maximum pH decrease and the surface area of the registered Stephan curve (delta pH.min) were used as measures of acid production. The results indicate that the volume of "saliva" in the mouth before and after swallowing, the unstimulated salivary flow rate, and the buffer capacity had significant influences on the extent of the pH changes. Other factors, such as the maximum flow rate, the delay between start of stimulation and maximum flow, the volume of saliva in the mouth at time zero, and the taste threshold for sugar, were of lesser importance, confirming some predictions from the computer model.

Buffers↗