Detection of a Target Taste in a Complex Masker

Detection thresholds for sodium chloride were compared in aqueoussolution, in mixture with a sucrose masker, in mixture witha citric acid masker, and in mixture with both of these maskerstogether. Separately the two maskers raised the threshold ofsodium chloride by three to four times, and together by overnine times, a result consistent with independence (additivity)of the two masking effects. To achieve comparable masking witheither sucrose alone or with citric acid alone would requireincreasing their masking concentrations by about ten times.Hence multiple masking can be a far more efficient means ofconcealing a taste, whether an unpleasant one (e.g. the bittertaste of medicine) or a pleasant one (e.g. a salty or sweetcondiment). Multiple masking has dietary and culinary significance,especially for middle aged and elderly persons concerned aboutsalt intake, because their thresholds for NaCl, whether withor without maskers, are typically two or three times higherthan those of youthful persons. Chem. Senses 22: 529–534,1997.     

The influence of common food additives and temperature on threshold perception of capsaicin

The effects of 0.01, 0.06, 0.15 and 0.29 M sucrose, 0.02, 0.09and 0.26 M sodium chloride, and 0.0005, 0.002 and 0.005 M citricacid upon the recognition threshold of capsaicin in ethanoland water solution were determined. The effects of 2, 18 and60°C on the recognition threshold of capsaicin were measuered.These temperature effects were also measured when 0.15 M sucrose,or 0.09 M sodium chloride was added to the medium. Eight samplesranging from 0.06 to 0.07 mg/l capsaicin were presented to ataste panel. Results showed a trend (p <0.001) of maskingpungency with the increasing concentrations of sucrose. A trend(p <0.01) of enhancement of pungency in 60°C solutionsand masking of pungency in 2°C samples was found. A trend(p <0.05) of masking and enhancing of pungency was foundwhen samples containing 0.15 M sucrose were similarly heatedand chilled. In samples which contained 0.09 M sodium chlorideand which were tested at 60°C and 2°C the sodium chloridereduced the masking and enhancing effects of the temperatureof the solutions. Unlike sucrose, sodium chloride and citricacid at 18°C were found to have no strong trend in affectingthe threshold level of capsaicin.     

Gustatory responsiveness to monosodium glutamate and sodium chloride in four species of nonhuman primates

The taste responsiveness of six squirrel monkeys, five pigtail macaques, four olive baboons and four spider monkeys to monsodium glutamate (MSG) and to sodium chloride was assessed in two-bottle preference tests of brief duration (2 min). When given the choice between tap water and defined concentrations of the two tastants dissolved in tap water, the animals were found to significantly discriminate concentrations of MSG as low as 2 mM (spider monkeys and olive baboons), 50 mM (pigtail macaques) and 300 mM (squirrel monkeys) from the solvent. With sodium chloride, taste preference thresholds were found to be 1 mM (spider monkeys), 20 mM (pigtail macaques), 50 mM (olive baboons), and 200 mM (squirrel monkeys), respectively. Across-species comparisons of the degree of preference for MSG and sodium chloride displayed by the four primate species showed the same order of spider monkeys>olive baboons>pigtail macaques>squirrel monkeys. When presented with equimolar concentrations of different tastants, all four species preferred sucrose as well as a mixture of sucrose and sodium chloride over MSG, and--at least at one concentration--they preferred MSG over sodium chloride. The results support the assertion that the taste responsiveness of the four primate species to MSG and sodium chloride might reflect an evolutionary adaptation to their respective dietary habits.     

Intensity and hedonic judgments of taste mixtures: an information integration analysis

Anderson's (1981) information integration approach was usedto examine taste mixture integration for intensity and hedonicjudgments of sucrose/sodium chloride and sucrose/citnc acidsolutions. In Experiment I, total intensity and hedonic ratingswere made for factorial combinations of sucrose and sodium chlorideor citric acid. The total intensity judgments produced an integrationpattern characterized by extreme subadditivity at high soluteconcentrations. (Subadditivity refers to the tendency for totalmixture intensity to be rated as less than the sum of the unmixedcomponent intensities.) The intensity judgment integration patternswere essentially identical for the two mixture types. However,the pattern of integration for the sucrose/sodium chloride andsucrose/citric acid mixtures differed for the hedonic ratings.Sucrose tended to eliminate the unpleasantness associated withincreasing concentrations of citric acid, while it only modulatedthis trend for sodium chloride. In Experiment II, subjects ratedthe individual sweet, salty and sour components of the mixturesto determine whether mixture suppression of the component tastescould account for the subadditivity of the total intensity judgmentsand/or the pattern of results for the hedonic ratings. It wasfound that sucrose suppressed the sour component of the sucrose/citricacid mixtures more than the salty component of the sucrose/sodiumchloride solutions This difference in component suppressionseemed to account for the hedonic integration patterns of thetwo mixture types which suggests that mixture suppression isan important factor to consider when predicting the pleasantnessof simple taste mixtures.     

Droplet freezing of antibody-linked indicator red cells of sheep, ox, and human origin

A droplet freezing technique for the cryopreservation of indicator red cells is described. Recovery was crucially dependent on the composition of the solution in which the cells were suspended. Preliminary experiments to determine the relative importance of sucrose, glucose, sodium chloride and hydroxyethyl starch (HES) in determining the survival of trypsin-treated sheep red cells showed that the addition of sucrose or HES or both to isotonic sodium chloride solution increased recovery, whereas the additional inclusion of glucose was detrimental. It was shown that glucose penetrated the cells whereas sucrose did not. The optimum combination of sucrose and sodium chloride concentration, in the presence of 6 g/dl HES, was 7 g/dl sucrose plus 0.3 g/dl sodium chloride. Recovery was increased by increasing the concentration of HES, and maximal recovery was obtained by thawing the frozen droplets in phosphate-buffered saline at 40 °C. Trypsintreated ox and human cells gave much lower recovery than sheep cells when HES was used in the freezing mixture but the substitution of dextran (10 g/dl) for HES gave greater than 80% recovery with all three species. Ten different antibody-coupled reagent cells all gave >83% recovery. The effects of hematocrit, incubation time, and storage temperature are described. The preservation technique described is simple and convenient, and will make it possible to extend the use of immunoassay procedures using antibody-coupled red cells.     

Detection of Tastes in Mixture with Other Tastes: Issues of Masking and Aging

When one taste (masker) is strong enough, it can completelymask another taste (target) of different quality. How strongthe masker must be to do this depends on how strong the targetis. As the target concentration is increased, the masking concentrationmust be increased, too, but in ever-increasing proportion. Toquantify the conditions for such complete masking, the target'sdetection threshold was measured as a function of the masker'sconcentration, from zero to strong. This was done for 12 binarycombinations of sucrose, sodium chloride, citric acid and quininehydrochloride. The 12 functions generated show that some tastantsmask each other much more efficiently than others. Masking givesnew insight into the role of aging in taste: older (66–90years) subjects' thresholds, regardless of masking concentration,always measured a constant factor higher than younger (18–29years) subjects' thresholds (about two to seven times higher,depending on target tastant). Thus, with increasing level ofthe masker, the thresholds of young and elderly go up in parallel.Thresholds of tastants in water alone are false predictors ofelderly persons' ability to perceive ingredients like salt andsugar condiments in foods, where, because of masking, theirthresholds can be several times higher than in water. Age manifesteditself relatively mildly in sucrose and citric acid, moderatelyin sodium chloride, and strongly in quinine hydrochloride. Chem.Senses 21: 211–221, 1996.     

Osmolar Concentration and Fixation of Mycoplasmas

Broth cultures of Acholeplasma laidlawii were fixed with various concentrations of cacodylate-buffered glutaraldehyde. The shape and ultrastructure of the organisms varied with the osmolar concentration of the fixative. When the fixation mixture was hypertonic to the culture medium, ultrathin sections suggested that the cells had shrunk. Phosphate buffer, sodium chloride, or sucrose at comparable osmolaities had the same effect as sodium cacodylate. Glutaraldehyde itself also contributed to the osmotic effects of the fixation mixture but to a lesser extent than salts or sucrose, to which the cell membrane is impermeable. The osmolar concentration of the fixation mixture seemed of greater importance than pH in determining morphology. The mycoplasma was still susceptible to damage by high concentrations of cacodylate after fixation with 2.5% glutaraldehyde. The best procedure was to fix and wash the organism under conditions isotonic with the growth medium. These conditions were also satisfactory for a filamentous mycoplasma, Mycoplasma orale.     

INGESTION AND EXPECTORATION SAMPLING METHODS OF FOUR TASTES IN A MODEL SYSTEM USING TIME-INTENSITY EVALUATIONS

The objective of this investigation was to compare two sampling methods (expectoration and ingestion) of single component water solutions (sweet—5% sucrose, sour—0.006% citric acid, bitter—0.027% caffeine, salty—0.325% sodium chloride) using time-intensity (T-I) evaluations. Analysis of variance was used to evaluate significant differences. There were subject inconsistencies for the recording times (RT) of sucrose, caffeine and sodium chloride tastes among the sampling methods. No panel differences were found for citric acid duration (RT) between ingested or expectorated samples. Individual contradictions for amplitude sucrose and sodium chloride mixtures were apparent however, the panel demonstrated no differences among the amplitude means between the sampling methods for citric acid and caffeine solutions. Aftertastes for ingested sodium chloride solutions were significantly (P < 0.01) greater than for expectorated samples whereas sampling techniques had no effect upon caffeine aftertastes. Individual contradictions were apparent for citric acid and sucrose aftertastes between the sampling methods.     

Combined effects of solutes and food preservatives on rates of inactivation of and colony formation by heated spores and vegetative cells of molds.

The combined and independent effects of sucrose, sodium chloride, potassium sorbate, and sodium benzoate on heat inactivation of conidia of Aspergillus flavus and Penicillium puberulum, ascospores of Byssochlamys nivea, and vegetative cells of Geotrichum candidum were studied. In addition, the effects of solutes and preservatives on colony formation by unheated and heated conidia of A. flavus were evaluated. Increased concentrations of sucrose were accompanied by increased tolerance to heat by A. flavus, B. nivea, and G. candidum. Low concentrations (3 and 6%) of sodium chloride protected A. flavus and G. candidum, whereas up to 12% sodium chloride protected B. nivea, but had little effect on the heat stability of P. puberulum. Potassium sorbate and sodium benzoate acted synergistically with heat to inactivate all four molds. At the same concentration, the two preservatives had varied degrees of effectiveness on molds and were influenced by the type of solute in the heating menstrua. Heated conidia of A. flavus had increased sensitivity to preservatives and reduced water activity, whether achieved by the presence of sucrose or sodium chloride, thus demonstrating heat-induced injury. At the same concentration, potassium sorbate was clearly more inhibitory than was sodium benzoate to colony formation by A. flavus, and the presence of sucrose and sodium chloride enhanced this inhibition.     

Gelatinisation of sago starch in the presence of sucrose and sodium chloride as assessed by differential scanning calorimetry

The inhibitory effect of sucrose and sodium chloride on sago starch gelatinisation was investigated by differential scanning calorimetry (DSC). The temperature of gelatinisation of starch in the presence of low levels of water and high levels of sucrose was found to increase in the presence of sucrose, whereas the gelatinisation enthalpy was unaffected. The gelatinisation temperature range was not as broad in the presence of sucrose as without sucrose. Furthermore, the shape of the gelatinisation endotherm was changed by the addition of sucrose. The double endotherm obtained in limited water:starch systems was changed into a single endotherm, similar to the endotherm obtained in excess water:starch systems at a higher temperature. DSC was also used to examine the effects of water and sodium chloride content on the phase transitions of sago starch. Samples were adjusted to starch:water ratios of 2:3 and 3:2 in sodium chloride concentrations of 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 M. The gelatinisation temperatures of sago starch increased and then decreased as the sodium chloride concentration increased. Sodium chloride created similar effects on the endotherms in excess water content and on the first endotherm with limited water content. In the presence of sucrose and sodium chloride, gelatinisation shifted to higher temperatures, and enthalpy associated with the endothermic process decreased. The extent of temperature shift and enthalpy change was dependent on the water to starch to solutes ratios.     

Conditioned aversion to sweet and salt in genetically obese and lean Zucker rats1

Conditioned taste aversion to threshold and suprathreshold concentrationsof sodium chloride, sucrose, and other sweeteners was measuredin obese and lean female Zucker rats. In the first experiment0.1M sodium chloride, 0.1M sucrose, or water was paired witha constant dosage of apomorphine hydrochloride (6.72 mg IP foreach rat). The magnitude of conditioned aversion to sucrose(0.1M and 0.316M) and sodium chloride (0.1M and 0.316M) followingthe initial conditioning trial was similar for obese and leanrats. However, repeated cycles of conditioning and extinctiontrials resulted in decreased sucrose intakes for obese ratsand increased sucrose intakes for lean rats. No changes in intakeoccurred with sodium chloride. In the second experiment 0.1M sucrose or water was paired withdoses of apomorphine hydrochloride based on each rat's bodyweight (30 mg/kg IP). The magnitude of aversion to sucrose (0.01M,0.0316M, 0.1M, 0.316M) and other sweetners (0.75M glucose, 0.1Msucrose, 0.001M sodium saccharin, and 0.025M sodium cyclamate)were similar for obese and lean rats. These data suggest thatrepeated testing with sucrose, rather than differences in sensorytaste factors, contributes to the previous reports of decreasedintake and sweet preference of obese rats.     

Sodium deprivation alters neural responses to gustatory stimuli

The effects of sodium deprivation for 10 d, a period sufficient to induce sodium appetite, on gustatory nerve discharges in rats were determined. Chorda tympani responses to concentration series of sodium chloride, sucrose, hydrochloric acid, and quinine hydrochloride were recorded and analyzed without the experimenter knowing the animal's deprivation condition. After deprivation, both whole nerve and single nerve fiber responses to sodium chloride were smaller; NaCl-best fibers, those more responsive to sodium chloride than to sucrose, hydrochloric acid, or quinine, were most affected. Thresholds had not changed; however, slopes of the stimulus-response functions for sodium chloride were lowered. Comparable changes in responses to the other stimuli did not occur. These results were discussed with respect to a possible relationship between changes in sodium chloride responsivity and changes in sodium intake, differences between methods of inducing sodium appetite, coding of taste quality and intensity, and mechanisms which might effect the responsivity change.     

Space and time separation of taste mixture components

Under natural conditions, all component qualities of taste mixturesco-exist in space and time on the tongue surface. The significanceof space-time coherence of taste sensations was investigatedby separating mixture components on the tongue. First, it wasshown that a mixture of sucrose plus sodium chloride is judgedto have a qualitatively different sweet taste from a mixtureof sucrose plus quinine sulphate when all taste qualities aretogether in space and time. This occurred even though mixtureswere matched for sweetness intensity, and the saltiness of theformer matched the bitterness of the latter. When, however,mixture components were spatially and temporally separated,the judged quality differences were eliminated. When the componentswere separated in space only, quality difference judgments werereduced in magnitude, but not eliminated. The results are consistentwith the hypothesis that space-time coherence of taste sensationsresult in perceptual blending and a consequent failure of selectiveattention to any single component. It is suggested that tastemixtures can be considered as single tastes even though componentqualities can be reliably identified using other techniques.     

Organic cations substituted for sodium are toxic to cultured rat glioma cells

As a prelude to studying the sodium dependence of choline-transport systems, a number of organic compounds plus LiCl, CsCl and RbCl as sodium substitutes were tested for toxicity to maintain isoosmolality or ionic strength on cultured rat astrocytoma cells. In short term experiments (1 hour), tetramethylammonium chloride, triethanolammonium chloride, guanidinium chloride, tris hydrochloride, mannitol, sucrose, LiCl, RbCl and CsCl were well tolerated. In long term exposure (4 days), no compound was completely nontoxic as a sodium substitute, but sucrose, mannitol, LiCl, and RbCl allowed maximum cell survival.     

Stimulation of sugar loading into sieve elements of willow by potassium and sodium salts

Potassium as the chloride, nitrate or sulphate or sodium as the chloride, were applied at a concentration of 50 mM either to the xylem of stem segments or to the cambial surface of bark strips of willow. Potassium chloride increased the concentration of sucrose in sieve tube exudate collected via severed aphid stylets, without significantly affecting the volume flow rate, or the concentration of potassium in the exudate. The increase in the sucrose level in the sieve tube sap was shown to be due to a stimulation of loading, rather than to an enhancement of longitudinal transport. Potassium nitrate and sulphate or sodium chloride, were not as effective as potassium chloride in stimulating the loading of sucrose. It is suggested that uptake of the cation into cells supplying sugars to the sieve tube is linked to the rate of release of sugars by the supplying cells.     

INTERACTION OF ASTRINGENCY AND TASTE CHARACTERISTICS1

The perception of astringency and basic taste in mixtures and their interaction effects were investigated by two procedures. In Experiment 1, focused and nonfocused testing procedures were compared using mixtures of low and high concentrations of alum and basic taste solutions. Both procedures yielded taste and astringency intensities that were modality‐dependent. Nonfocused testing was used in Experiment 2 to investigate the interactions of astringent phenolic (tannic acid) and nonphenolic (alum) compounds with each basic taste. Sweetness of sucrose increased with increased concentration with or without alum or tannin present. Changes in salty, bitter, and sour taste intensities were modality‐dependent. Astringency either remained unchanged or decreased with the addition of sucrose, sodium chloride, citric acid, or caffeine depending upon the taste concentration. Bitterness of tannin and alum at high concentrations was suppressed by the addition of sucrose, sodium chloride, or citric acid; sourness also decreased in the presence of sucrose or sodium chloride as well as a high level of caffeine.     

Utilization of the osmotolerance of sulphate-reducing bacteria in study of the genesis of subterranean waters

Cultures of sulphate-reducing bacteria from subterranean waters were divided into three groups, on the basis of their sensitivity to the sodium chloride concentration. The optimal sodium chloride concentration for group D1 cultures was 1% and under and the maximum tolerated concentration was 3.7%; in group D 4 cultures the optimal and maximum NaCl concentration were about 2% and 5.6% respectively and in group D 7 cultures about 3.5% and over 7% respectively. On using nutrient media containing 4% and 7% NaCl, these groups could be separated from a mixture and the bacterial count for each individual group could be determined. Study of the adaptation of these cultures to high sodium chloride concentrations showed that the group characteristics of the culture remained constant for at least ten passages. Comparative study of typical natural waters showed an incidence of D 1 bacteria in fresh water, but not in brackish water and sea water. The two latter types contained group D 4 and D 7 bacteria, the proportion of the latter group increasing with the degree of mineralization of the water. Study of the incidence of groups of sulphate-reducing bacteria was combined with other microbiological and hydrochemical indicators for resolving questions of the genesis of subterranean waters in Carpathian flysch. The results showed that the presence of variously mineralized hydrogen sulphide waters of different origin as regards their connection with the surface could be determined on the basis of the given criteria. The resultant picture corresponds to the recent state of the water and thus does not permit determination of the sedimentation system of the given water-bearing horizons.     

Fate of aflatoxins B1 and G1 residues during biscuit processing

Effect of biscuit processing on the destruction of aflatoxins B₁ and G₁ with and/or without some commonly leavening agents used namely sodium bicarbonate, ammonium bicarbonate and sodium bisulfite and sodium chloride. It was found that mixing step reduced the concentration of aflatoxins B₁ and G₁ by 80.7% and 82.7%, while the effect of baking step being 28.9% and 21.5%. The effect of mixing was found to be more pronounced than that baking step. The highest destruction effect on aflatoxin B1 was observed by adding a mixture composed of sodium and ammonium bicarbonate and sodium bisulfite followed by sodium chloride, sodium bisulfite, ammonium bicarbonate and/or sodium bicarbonate alone, where the reduction values of toxin after mixing were 93.4,91.9,91.7, 88.8 and 86.6% respectively, while the baking effect ranged 17.2 to 34.5% in the presence of different leaving agents added. Concerning aflatoxin G1; the highest destructive effect of toxin was adsorbed by adding a mixture of sodium and ammonium bicarbonate and sodium bisulfite followed by sodium bisulfite, sodium chloride, ammonium bicarbonate and/or sodium bicarbonate alone since the destruction values of such toxin after mixing were 96.2%, 92.8%, 92.6%, 89.0% and 87.7% respectively, while the baking effect ranged 20.9 to 34.5% in all leavening agents added.     

The Effect of Osmotic Value of the Medium on the Growth of the Young Sunflower Embryos Cultured in Vitro

The present paper deals with the effect of osmotic value of the medium on the growth of the young sunflower embryos grown in vitro. Based upon the results of a series of experiments carried out during 1963 the following conclusions are reached: 1. The sunflower embryos grown in vitro require different concentrations of sucrose, varying with the age at which the embryos are excised. Generally speaking, the optimum concentration of sucrose for the embryos 1,000–1,100μ in length is about 17.5%, for 2,000–2,500 μ, about 16% and for 5,000–5,500 μ, about 12.5%. 2. The sucrose may be partially replaced by sodium chloride (0.2%–0.4%) or mannitol (1.125%–5.5%) as an osmotically active substance, but 0.8% sodium chloride is apparently toxic to the young embryos. 3. Embryos cultured in hypotonic medium usually germinate precociously, those in approximately isotonic medium continue their embryonic growth, while those in hypertonic medium become more or less checked in their growth.