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PubMed2004

Furfuryl ethyl ether: important aging flavor and a new marker for the storage conditions of beer.

Recently, it was reported that furfuryl ethyl ether is an important flavor compound indicative of beer storage and aging conditions. A study of the reaction mechanism indicates that furfuryl ethyl ether is most likely formed by protonation of furfuryl alcohol or furfuryl acetate followed by S(N)2-substitution of the leaving group by the nucleophilic ethanol. For the reaction in beer, a pseudo-first-order reaction kinetics was derived. A close correlation was found between the values predicted by the kinetic model and the actual furfuryl ethyl ether concentration evolution during storage of beer. Furthermore, 10 commercial beers of different types, aged during 4 years in natural conditions, were analyzed, and it was found that the furfuryl ethyl ether flavor threshold was largely exceeded in each type of beer. In these natural aging conditions, lower pH, darker color, and higher alcohol content were factors that enhanced furfuryl ethyl ether formation. On the other hand, sulfite clearly reduced furfuryl ethyl ether formation. All results show that the furfuryl ethyl ether concentration is an excellent time-temperature integrator for beer storage.

Beer↗
PubMed1981

Studies of electrochemical action in the oral cavity.

A method for in vivo measurements of potentials and polarizations of metallic dental restorations was presented. The precision of this method allowed for calculation to be made of the electrochemical action in the oral cavity in terms of currents created at contact between metallic restorative materials. With this method, an epidemiological investigation was performed on persons, who had received dental treatments including extensive metallic restorations. Those persons suffering from oral symptoms allegedly caused by oral galvanism were not found to have higher electrochemical action in the oral cavity than persons, selected as a control, without symptoms ascribed to oral galvanism. Persons ailing from this type of symptoms showed, however, lower threshold levels for electric stimulation, examined with an electrogustometric method, than persons without symptoms. Finally, determination of the saliva concentrations of various metallic components with atomic absorption spectrophotometry did not reveal any differences between persons with or without metallic restorations. Neither were any correlations found between saliva ion concentrations and the magnitude of currents created at metallic contact between dental restorations.

Adolescent↗
PubMed2003

Evolution of chemical and sensory properties during aging of top-fermented beer.

The aging and consequent changes in flavor molecules of a top-fermented beer were studied. Different aging conditions were imposed on freshly bottled beer. After 6 months of aging, the concentration changes were recorded for acetate esters, ethyl esters, carbonyls, Maillard compounds, dioxolanes, and furanic ethers. For some flavor compounds, the changes with time of storage were monitored at different temperatures, either with CO(2) or with air in the headspace of the bottles. For some molecules a relationship was determined between concentration changes and sensory evaluation results. A decrease in volatile esters was responsible for a reduced fruity flavor during aging. On the contrary, various carbonyl compounds, some ethyl esters, Maillard compounds, dioxolanes, and furanic ethers showed a marked increase, due to oxidative and nonoxidative reactions. A very high increase was found for furfural, 2-furanmethanol, and especially the furanic ether, 2-furfuryl ethyl ether (FEE). For FEE a flavor threshold in beer of 6 mug/L was determined. In the aged top-fermented beer, FEE concentrations multiple times the flavor threshold were observed. This was associated with the appearance of a typical solvent-like flavor. As the FEE concentration increased with time at an almost constant rate, with or without air in the headspace, FEE (and probably other furanic ethers) is proposed as a good candidate to evaluate the thermal stress imposed on beer.

Beer↗
PubMed1976

[New methods for analysis and evaluation of sensory qualities of foods and calculation of changes. 10. Quantitative titrimetric determination of irradiation flavor in apple juice and concentrate and its dependence on radiation dosage].

Irradiation flavour in apple juice and concentrate which is mainly attributable, according to our previous studies, to tetrahydrofuran (THF) that may be quantitatively determined by means of the so-called mercury acetate method. This is based on the fact that the amount of a 4% solution of mercury acetate needed for removing the THF odour is proportional to the THF concentration. Using this method, the amounts of THF produced by various gamma radiation doses (varying from 0.64 to 2.55 Mrad) could be determined titrimetrically. Calculations showed that the THF concentration increases linearly with the radiation dose. Thus, the minimum radiation doses at which the irradiation flavour is first perceived (threshold of perception) may be calculated readily. The mercury acetate method is also a model case of the use of subjective olfactometry for the quantitative determination of flavour key substances in foods so far as they may be quantitatively determined by means of chemical reactions since the endpoint of titration is controlled by the sense of smell.

Chemical Phenomena↗
PubMed1994

Competitive inhibition of the nickel-induced response to choline by calcium ions in single water fibers of the frog glossopharyngeal nerve.

NiCl2 induces a response to choline Cl and enhances the response to CaCl2 in water-sensitive fibers (water fibers) of the frog glossopharyngeal nerve. The Ni(2+)-induced choline+ response was inhibited by Ca2+ ions and, conversely, the enhanced Ca2+ response by Ni2+ ions was inhibited by choline+ ions. Hence, there exists a mutual antagonism between Ca2+ and choline+ ions. In the present study, the inhibition of the Ni(2+)-induced choline+ response by Ca2+ ions was investigated quantitatively. The assumption was made that receptors for choline (XCh) exist and that binding of a choline+ ion to XCh brings about a neural response. It was further assumed that the magnitude of the neural response is proportional to the amount of choline-XCh complex minus some constant (the threshold concentration of the choline-XCh complex). The results from analysis of double-reciprocal plot were consistent with the hypothesis that Ca2+ ions compete with choline+ ions for XCh. The dissociation constants for the choline-XCh complex and the CaXCh complex were obtained to be 0.6 M and 7.4 x 10(-5) M, respectively. This result indicates that the affinities of XCh for choline+ and Ca2+ ions are very different. Furthermore, Mg2+ ions did not affect the Ni(2+)-induced choline+ response, an indication that the affinity of XCh is not charge-specific, but is chemically specific. The identification of a competitive inhibitor of the choline+ response provides evidence for existence of a choline-specific receptor at the surface of taste cells that are innervated by the water fibers of the frog glossopharyngeal nerve. Differences between the features of the response to choline Cl in the chorda tympani nerve of the rat and those in the frog glossopharyngeal nerve are discussed.

Animals↗
PubMed2001

Volatile flavour components of baked potato flesh. A comparison of eleven potato cultivars.

Tubers of eleven cultivars of potato were baked and the flavour compounds from the flesh were isolated by headspace adsorption onto Tenax and analysed by gas chromatography-mass spectrometry (GC-MS). Lipid degradation and the Maillard reaction were the main sources of flavour compounds, accounting for 22-69% and 28-77%, respectively, of the total yields. Various sulfur compounds, methoxypyrazines and terpenes were also identified at lower levels. Relative aroma impact values (RAVs) were calculated by dividing compound yields by the odour threshold value. Compounds contributing most to aroma (RAV > 10,000 in at least one cultivar) were 2-isobutyl-3-methoxypyrazine, 2-isopropyl-3-methoxypyrazine, beta-damascenone, dimethyl trisulfide, decanal and 3-methylbutanal. The observed differences in yields and RAVs for compounds among cultivars would be expected to result in differences in perceived flavour.

Cooking↗
PubMed1986

Control of sensorimotor function by dopaminergic nigrostriatal neurons: influence on eating and drinking.

The literature on the effects of lesions of the lateral hypothalamic area (LHA) on eating and drinking is reviewed in an effort to understand the function of the neural substrate destroyed. The data suggest that damage to the dopaminergic nigrostriatal neurons that course through the LHA results in a decrease in sensorimotor facilitation; that is, an increase in the threshold for responding to stimuli that elicit orientation, approach and consumption. This increase results in decreased consumption of food and water. Evidence is also reviewed suggesting the possibility that striatal dopaminergic activity may mediate a negative feedback signal related to blood glucose level that influences responsiveness to food, and therefore eating. There is no evidence that the nigrostriatal system mediates a similar signal related to water balance and drinking. A second deficit associated with LHA lesions, caused by damage to the pallidofugal neurons that descend through this area, is a dysfunction of motor control of the head and mouth. This results in an increase in the effort required to consume food and water, also leading to decreased consumption. These two behavioral factors: an increased threshold for responding to the sensory properties of food and water and an increase in the effort required to eat and drink are used to explain the symptoms making up the lateral hypothalamic syndrome without postulating changes in physiological regulatory (set point) mechanisms.

Animals↗
PubMed2006

Long-term assessment after implantation of the Vibrant Soundbridge device.

OBJECTIVE: To present long-term results with a semi-implantable middle ear implant, the Vibrant Soundbridge (VSB), and analyze pre- and post-operative results of audiologic tests. STUDY DESIGN: Retrospective chart review with additional patient interview and audiologic testing. SETTING: One tertiary referral center. SUBJECTS: Twenty patients who met the selection criteria of the manufacturer were evaluated at least two years after implantation. INTERVENTIONS: Monaural Implantation of the VSB in 20 patients, in two of these 20 patients implantation of the second ear in a second stage. RESULTS: Assessment of benefit and satisfaction using the standardized International Outcome Inventory for Hearing Aids, the Glasgow Benefit Inventory, and Visual Analogue Scales in all patients. Fifteen patients agreed to undergo audiologic testing at follow-up including pure-tone- and speech audiometry in silence and noise. The majority of patients (13/20) reported to be satisfied or very satisfied with the VSB. Aided speech perception was comparable between the VSB and the hearing aid preoperatively. When compared to the preoperative audiograms, residual hearing from 0.5-4 kHz was significantly worse in the operated ear with 8 dB (Wilcoxon signed rank test p < 0.001) but only 2.6 dB in the non-operated ear (Wilcoxon signed rank test, p > 0.05). Major surgical complications did not occur. Permanent alteration in taste occurred in three patients and revision surgery was necessary in another three patients. CONCLUSION: Satisfaction with the VSB was not superior to conventional hearing aids in subjective and in audiometric terms. Because of its impact on residual hearing and the requirement of implantation middle ear surgery, implantation of the VSB should be limited to patients with relevant side effects of hearing aids, e.g., severe chronic otitis externa.

Adult↗
PubMed1995

Sensory- and memory-mediated olfactory dysfunction in Huntington's disease.

Neuropathology in Huntington's disease (HD) known to project to areas that process olfactory information raises the questions of which olfactory function, if any, is most affected in HD, and how to explain such dysfunction in terms of olfactory sensitivity and cognition. These questions were studied by comparing HD patients and controls (matched for age, gender, and education) on absolute detection, intensity discrimination, quality discrimination, short-term recognition memory, and lexical- and picture-based identification for odor. Taste or vision were used as comparison modalities. The results suggest that whereas odor-recognition memory is not affected in patients with HD, these patients have impaired olfactory functioning with respect to absolute detection, intensity discrimination, quality discrimination, and identification. The three latter impairments were significantly explained by poor detection sensitivity. Odor identification was the function most affected.

Adult↗
PubMed1990

Quantal vs. graded generalization in drug discrimination: measuring a graded response.

In drug discrimination research, detection of drug stimuli by animals is used for investigating various properties of psychoactive drugs. The major issue addressed by this paper is whether detection of drug stimuli by animals is a quantal or graded event. Some data suggest that detection of a drug stimulus by animals is quantal in nature. Thus, variations in drug stimulus substitution may only reflect variations in threshold for detecting the training stimulus rather than the current concept of these data reflecting graded responding to stimulus intensity. Therefore, drug discrimination procedures may have limited utility for detecting quantitative differences in the subjective effects of varying drug doses. In order to examine this problem, a method for measuring continuous response gradients in individual animals is needed. Tests for quantal responding generally use the distribution of responses on two manipulanda as the dependent measure. However, this variable may be inadequate for detecting a graded response, and may actually reflect loss of stimulus control or a deterioration in performance, rather than changes in response magnitude. Most alternative measures utilize response rate. Unfortunately, these measures are influenced by the direct rate-altering properties of some drugs. One possible alternative method is conditioned taste aversion as the discriminative task. This paradigm provides a means for not only ascertaining if graded discriminative responses occur in individual animals, but also more rapidly training a drug discrimination. Thus, using conditioned taste aversion techniques for measuring a drug discrimination may provide better indices for detecting response gradations.

Animals↗
PubMedDate not supplied

Sensory acuity and reasoning in delusional disorder.

Systematic research on delusional disorder (DD) is limited. The goal of this study was to assess DD patients in the following areas: sensory capacities, decision-making style, and complex reasoning. Ten DD patients and 10 matched normal controls completed the following (1) smell, taste, and vision testing; (2) a probabilistic inference test in which subjects made probability decisions; and (3) a gambling task assessing complex reasoning. No significant difference was found between DD subjects and normals for taste acuity, olfactory acuity, or olfactory discrimination. No difference in visual acuity was noted, but sample size was limited. In addition, DD subjects required significantly less data to make probability decisions than normal controls. Despite using less data, DD subjects were as certain as controls regarding the accuracy of their decisions. As for complex reasoning, DD subjects performed as well as normal controls, but tended to surmise the purpose of the task sooner than normals, a difference that approached significance. In conclusion, these results suggest no differences between DD and normal subjects regarding olfaction, taste, and vision. The reasoning studies suggest that DD subjects may have a "cognitive set" that predisposes them to make conclusions with significantly less data than normals. Further, the study suggests that this reasoning difference generalizes to events outside the DD subjects' delusional realm and can be evoked in an experimental environment.

Adult↗
PubMed1998

Sensory and objective characteristics of broiler meat from commercial broilers fed rendered spent hen meal.

The objective of the study was to determine sensory and objective characteristics of broiler breast and thigh meat from commercial broilers fed rendered spent hen meal (RSHM) from hatch to 42 d of age. Breast and thigh muscles from 90, 6-wk-old straight-run broilers (i.e., mixed male and female broilers) fed starter and grower diets consisting of either 0, 8, or 12% RSHM were evaluated for sensory characteristics, instrumental texture, and compositional profiles. The RSHM treatments had no adverse effects (P > 0.05) on juiciness, chicken flavor intensity, tenderness, or compositional profiles for the breast or thigh meats. Off-flavor scores for all treatments were above the threshold value, indicating that the RSHM imparted no off-flavors to the breast and thigh meats. Warner-Bratzler shear measurements were similar (P > 0.05) for breast meat from broilers in all treatments. No shear measurements were conducted for the thigh meat. It was concluded that RSHM can be incorporated into the diets of broilers at levels of up to 12% without causing objectionable sensory characteristics in the cooked broiler meat.

Animal Feed↗
PubMedDate not supplied

[The effect of ouabain on the sugar receptor of the contact chemoreceptive sensilla of the fly Protophormia terraenovae].

Studies have been made on the inhibitory effect of ouabain solutions on bioelectrical activity of the labellar sensillae of flied. It was shown that 10(-2) M ouabain solution irreversibly inhibits the activity, where as 10(-3) and 10(-4) M concentrations decrease the frequency of impulses within 40-60 min. Ouabain solution is a specific stimulator of the sugar receptor of the sensillae with a threshold of 10(-7) M; in combination with 0.2 M glucose, it inhibits impulse activity with the first 200 msec of stimulation. The effect is observed in a narrow zone of ouabain concentrations, with a maximum approximately at 10(-4) M. Differences between the effects of the inhibitor at the vicinity of the onset of generator potential and those in the impulse activity zones on the membrane of the sensory cell are suggested.

Animals↗
PubMed1969

Shark pit organs: response to chemicals.

Nerve fibers from pit organs and canal neuromasts are distinguished by the nature of their electrophysiological response to mechanical and chemical stimulation. Pit organs respond to touch but have a relatively high threshold compared with canal neuromasts. They respond readily to sodium and potassium chloride solutions, the rate of discharge increasing with the concentration of the solution. Order of effectiveness with 1 molar solutions of monovalent cations is as follows: potassium, rubidium > sodium, ammonium > cesium, lithium. Anions are ineffective. Divalent cations such as calcium and magnesium are inhibitory. Responses to acid, sugar, and quinine are either very slight or inhibitory.

Animals↗
PubMed1994

Inhibition of isotonic sodium chloride intake in the rat by selective tachykinin agonists.

The present study investigated the effect of the central injection of selective tachykinin (TK) agonists on the need-free intake of 0.9% NaCl in rats. Isotonic NaCl was offered for 60 min (between 1800 and 1900 h); water was offered for 4 h (between 1800 and 2200 h). The TK agonists were injected into the third ventricle just before access to fluids. The NK3-selective agonists [Asp5,6,MePhe8]substance P(5-11) and Succ[Asp6,MePhe8]substance P(6-11), as well as the NK1-selective agonist [Sar9, Met(O2)11]substance P, markedly reduced salt intake, the threshold dose for their effects being 5 ng/rat. The NK2-selective agonist GR64349 reduced salt intake only at 500 ng/rat. At the dose of 31.2 ng/rat, neither the NK1 nor the NK3 agonists inhibited water intake, when water was the only fluid offered (between 1800 and 2200 h), or modified food intake in food-deprived rats. The present study shows that a) TKs inhibit not only the need-induced salt intake, but also the need-free intake of isotonic saline, b) this effect is behaviorally selective, and c) the effect is apparently mediated by NK1 and NK3 receptors. The finding that TKs suppress salt intake in a large variety of experimental conditions supports the idea that the antinatriorexic effect of TKs is independent of the physiological and hormonal status of the animal. It is hypothesized that TKs might modify taste sensitivity or the hedonic evaluation of the salty taste.

Animals↗
PubMed1993

Growth and body composition of periurban Guatemalan children in relation to zinc status: a cross-sectional study.

In a study of periurban Guatemalan school-children (89 males, 73 females) aged 81.5 +/- 7.0 mo (mean +/- SD), height, weight, arm circumference, and triceps-skinfold-thickness (TSF) measurements were examined in relation to plasma and hair zinc concentrations, plasma and red blood cell alkaline phosphatase activities, recognition thresholds for salt (RTS), delayed-cutaneous hypersensitivity response to seven recall skin test antigens, and cognitive measures. Children were stunted [median height-for-age (HA) Z score -1.49] but not wasted [median weight-for-height (WH) Z score 0.20], with median midarm muscle area (MAMA) and midarm-fat area (MAFA) Z scores of -0.57 and -0.35, respectively. Of the children, 63.5% of males and 44.1% of females had hair zinc < 1.68 mumol/g (P < 0.05); 12.3% of males and 1.5% of females had plasma zinc < 10.71 mumol/L (P < 0.05). Children with hair zinc < 1.68 mumol/g had higher (P < 0.05) medians for WA Z and WH Z scores, RTS, and phytic acid intake than did those with hair zinc > or = 1.68 mumol/g. Zinc status explained some of the variance in growth (HA, WA, and WH Z scores), body composition (MAFA Z scores), and taste acuity. Suboptimal zinc status arose partly from diets low in readily available zinc.

Aging↗
PubMed2003

Role of gustation in the recognition of oleate and triolein in anosmic rats.

Recent studies suggest a chemical perception of dietary fat in the oral cavity. To examine the role of gustation for the recognition of oleate and triolein, very short-term (5-min), two-bottle preference tests were conducted in anosmic rats. To minimize the effects of olfaction, texture and postingestive effects, rats were rendered anosmic with intranasal zinc sulfate, test substances were suspended in 0.3% xanthan gum solution and test fluids were offered for 5 min. Rats preferred oleate fluid but not triolein fluid to the control of 0.3% xanthan gum solution. The preference threshold for oleate in the rat oral cavity was between 0.2% and 0.5%. In the two-bottle preference tests between oleate and triolein, rats preferred oleate fluid to triolein fluid, showing discrimination of oleate and triolein. The results suggest that rat recognizes oleate by a gustatory cue and that fatty acid but not triglyceride is important for gustatory recognition of fat.

Animals↗
PubMed2002

Fresh cucumber flavor in refrigerated pickles: comparison of sensory and instrumental analysis.

The ability of nonacidified, refrigerated pickled cucumbers to produce the fresh cucumber flavor impact compounds (E,Z)-2,6-nonadienal and (E)-2-nonenal declined during storage. Production of these compounds decreased as the pH of refrigerated cucumbers was reduced. Despite the fact that the concentrations of (E,Z)-2,6-nonadienal and (E)-2-nonenal generated were over 10(5)-fold greater than the threshold levels, it was possible for a sensory panel to consistently detect differences in the intensity of fresh cucumber flavor, provided the pH difference between samples was 1 unit or greater. The presence of spices did not interfere with the ability of panelists to detect differences in fresh flavor intensity. There was a linear correlation between sensory scores and the amount of (E,Z)-2,6-nonadienal produced by cucumbers equilibrated at different pH levels.

Aldehydes↗