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Sucrose Taste Thresholds of Rats and Humans

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Abstract

Rats could drink from either of two bottles, one of which contained distilled water, the other in which the sucrose concentration was daily increased. The sucrose taste threshold was taken to be that point at which the rats began to drink more sucrose solution and less distilled water. It was found that the sucrose threshold of rats was a concentration of 0.5% as compared to a sweet threshold of 0.4 to 0.7% and a taste difference threshold of 0.17% in humans. (PsycINFO Database Record (c) 2012 APA, all rights reserved)

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... When it comes to taste detection thresholds, many investigators have reported a decrease in sucrose sensitivity with age (Bartoshuk, Rifkin, Marks, & Bars, 1986;Cooper, Bilash, & Zubek, 1959;Fikentscher, Roseburg, Spinar, & Bruchmuller, 1977;Hermel, Schonwetter, & Samueloff, 1970;Moore, Nielsen, & Mistretta, 1982;Richter & Campbell, 1940) and some included children in their taste sensitivity studies (Cooper et al., 1959;Fikentscher et al., 1977;Hermel et al., 1970;Richter & Campbell, 1940). ...
... When it comes to taste detection thresholds, many investigators have reported a decrease in sucrose sensitivity with age (Bartoshuk, Rifkin, Marks, & Bars, 1986;Cooper, Bilash, & Zubek, 1959;Fikentscher, Roseburg, Spinar, & Bruchmuller, 1977;Hermel, Schonwetter, & Samueloff, 1970;Moore, Nielsen, & Mistretta, 1982;Richter & Campbell, 1940) and some included children in their taste sensitivity studies (Cooper et al., 1959;Fikentscher et al., 1977;Hermel et al., 1970;Richter & Campbell, 1940). ...
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SUCROSE THRESHOLDS AND GENETIC POLYMORPHISMS OF SWEET AND BITTER TASTE RECEPTOR GENES IN CHILDREN Paule Valery Joseph Charlene Compher, PhD, RD Background: Many illnesses of modern society are due to poor food choices. Excess consumption of sugars has been associated with obesity and diabetes. Children, due to their basic biology, are more vulnerable than adults to overeat foods rich in sugars. Little research has focused on whether there are individual differences among children in their sensitivity to sweet taste and if so the biological correlates of such differences. Aims: The goal of this study was to determine whether variations in children’s sucrose detection thresholds relate to their age and sex, taste genotype, added sugar or caloric intake, temperament or food neophobia and adiposity. Methods: Sucrose detection thresholds in children age 7-14 years were tested individually using a validated two-alternative, forced-choice, paired-comparison tracking method. Genetic variants of taste receptor genes were assayed: TAS1R2, TAS1R3 and GNAT3 (sweet taste receptor genes; one variant each) and the bitter receptor gene TAS2R38 (three variants). Children (n=216) were measured for body weight and height. A subset of 96 children was measured for percent body fat, waist to height ratio and added sugar and kcal intake. Results: Mean sucrose threshold was 12.0 (SD 12.9), 0.23 to 153.8 mM. Girls were more sensitive than boys [t(214) = 2.0, p=0.047] and older children more sensitive than younger children [r(214) = -0.16, p = 0.016]. Variants in the bitter but not the sweet taste receptor genes were related to sucrose threshold and sugar intake; children with two bitter-sensitive alleles could detect sucrose at lower concentrations [F(2,165) = 4.55, p = 0.012; rs1726866]. Children with these variants also reported eating more added sugar (%kcals; [F(2, 62) = 3.64, p = 0.032]) than did children with less sensitive alleles. Sucrose detection thresholds predicted central adiposity [F(2, 59) = 6.1, p = 0.016), but not percent body fat [F(2, 58) = 1.4, p = 0.238]) when adjusted for added sugar intake, temperament, age, sex and negative reaction to foods. Conclusions: Differences in sweet taste sensitivity may affect childhood dietary sugar intake with long-term health consequences, including obesity. There may be a more complex interplay between the bitter and sweet taste systems during development than previously appreciated. Understanding taste related parameters as well as other dimensions that may affect food consumption might help in developing weight management to minimize childhood obesity risk.
... There is no consensus in the literature regarding the concentration of sucrose solution at which animals begin to stably distinguish it from plain water. For example, Richter C. and Campbell K., determining the taste threshold for sucrose solution for rats, found that it corresponds to 0.5% [146]. Subsequent studies indicated threshold values of 0.34% [147], 0.32% [148], 0.09% [149], and 0.08% [150]. ...
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Despite numerous studies on the neurobiology of depression, the etiological and pathophysiological mechanisms of this disorder remain poorly understood. A large number of animal models and tests to evaluate depressive-like behavior have been developed. Chronic unpredictable mild stress (CUMS) is the most common and frequently used model of depression, and the sucrose preference test (SPT) is one of the most common tests for assessing anhedonia. However, not all laboratories can reproduce the main effects of CUMS, especially when this refers to a decrease in sucrose preference. It is also unknown how the state of anhedonia, assessed by the SPT, relates to the state of anhedonia in patients with depression. We analyzed the literature available in the PubMed database using keywords relevant to the topic of this narrative review. We hypothesize that the poor reproducibility of the CUMS model may be due to differences in sucrose consumption, which may be influenced by such factors as differences in sucrose preference concentration threshold, water and food deprivation, and differences in animals’ susceptibility to stress. We also believe that comparisons between animal and human states of anhedonia should be made with caution because there are many inconsistencies between the two, including in assessment methods. We also tried to offer some recommendations that should improve the reproducibility of the CUMS model and provide a framework for future research.
... Alternatively, age-related differences in ethanol preference may be due to differences in taste sensitivity. However, experimental evidence indicates that sensitivity declines with age in animals and man (e.g., Glanville, Kaplan, & Fischer, 1964;Goodrick, 1967;Richter & Campbell, 1940). If taste were a factor in the present study, one would expect that, with reduced taste sensitivity, older animals would exhibit a greater preference for ethanol than younger animals, but just the opposite occurred. ...
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Older animals “slept” twice as long as younger animals following injection of ethanol (4 g/kg), although blood alcohol concentrations at time of awakening were not significantly different. Older mice also slept approximately twice as long as younger mice following injection of pentobarbital Na (50 mg/kg). Ethanol (3 g/kg) depressed gross motor activity of older animals more than younger animals. When tested for their preference for various concentrations of ethanol vs. water, younger animals exhibited a greater preference than older animals at all but two of the concentrations tested.
... Most such studies have used traditional psychophysical methods, apparently with the implicit assumption that the various specific methods are equivalent. Such an assumption may be untenable when the differences in methodology are closely examined (Richter & Campbell, 1940). ...
Article
Ten smokers and 10 nonsmokers were compared for taste sensitivity to sucrose on two discrimination tasks, one at near-threshold (NT) concentration level and one at suprathreshold (ST) concentration level. The data were analyzed using the ds and area under ROC curve measures based on the theory of signal detection (TSD). and by using the percentage correct responses. Analysis of both TSD measures showed smokers to be significantly more sensitive than nonsmokers on the NT .task and more sensitive on the ST task, but not significantly so. Comparison of mean percent correct responses showed no significant differences. A reflexive enhancement phenomenon was suggested as a possible interpretation. A decreased sensitivity to the bitter taste in smokers apparently results in an increased sensitivity to the sweet taste.
... Still, there is evidence in the literature of interindividual differences with regard to sweet. In 1939, Richter and Campbell (1939) tested sucrose recognition thresholds in 45 young adults and found that 13 exhibited elevated thresholds (>17.5 mM), well in excess of the population mode (5.8 mM) or the modern accepted value (3 mM). More recently, Faurion (1993) asked 55 subjects to match sucrose solutions in intensity to a 29 mM sodium chloride reference. ...
Article
Abstract1 Sweet is classically considered to be a single perceptual experience. However,2 diverse compounds can elicit this sensation, suggesting the existence of multiple3 pathways toward this end. This paper presents an overview of chemical theories of4 sweetness, reviews the phylogenetic and behavioral evidence for multiple pathways, and5 presents a summary of recent molecular advances regarding the sweet receptor. Potential6 sites for signal integration are discussed, and potential implications for nutritionists and7 food scientists are discussed.8 9
... An overview of research studies indicates that the detection threshold (DT) and recognition threshold (RT) for simple basic tastes (sweet, sour, salty, and bitter) are moderately elevated in older persons compared to a younger cohort (e.g., Richter, C. P. and Campbell, K. H., 1940;Harris, H. and Kalmus, H., 1949;Bourlière, F. et al., 1958;Hinchcliff, R. 1958;Cooper, R. M. et al., 1959;Kalmus, H. and Trotter, W. R., 1962;Glanville, E. V. et al., 1964;Smith, S. E. and Davies, P. D., 1973;Grzegorczyk, P. B. et al., 1979;Murphy, C., 1979;Schiffman, S.S. et al., 1979;Dye, C. J. and Koziatek, D. A., 1981;Schiffman, S. S. et al., 1981;Moore, L. M. et al., 1982;Weiffenbach, J. M. et al., 1982;Schiffman, S. S. et al., 1990;Schiffman, S. S., 1993;Schiffman, S. S. et al., 1994;Stevens, J. C. et al., 1995;Stevens, J. C., 1996;Stevens J. C. and Traverzo, A., 1997;Schiffman, S. S. et al., 1998;Mojet, J. et al., 2001;Yamauchi, Y. et al., 2002;Fukunaga, A. et al., 2005). An elevated DT indicates that the elderly require the presence of more molecules (or ions) for a sensation to be perceived compared to younger persons -that is, the elderly have reduced absolute sensitivity. ...
Article
Worldwide, the segment of the population aged 65 years and above is escalating rapidly and is expected to reach 1.5 billion by 2050. This increase in elderly persons presents many global challenges including addressing perceptual changes in the sense of taste that can reduce quality of life, increase the risk from food poisoning, and lead to inadequate nutritional status especially in the sick or malnourished elderly. Older persons have elevated taste thresholds as well as reduced capacity to discriminate among suprathreshold taste stimuli. These decrements in taste sensitivity can result from normal aging but are exacerbated by certain disease states, pharmacological and surgical interventions, radiation, and environmental exposure. Comparison of medicated and nonmedicated elderly indicates that taste distortions are more common in persons taking multiple medications. There are no standard medical treatments for taste alterations experienced by the elderly, but current biochemical research may ultimately provide useful insights for treating taste losses that occur in older individuals.
... The procedure designed for determining taste threshold in primates, the two-bottle test, has been initially used by Glaser (1968), following the pioneering work of Richter & Campbell (1939) on rodents. A solution of a compound (for instance sucrose) is presented simultaneously with a bottle of water, and the spontaneous consumption of each liquid is recorded. ...
Chapter
Full-text available
Gustatory perception is usually assessed by a measurement of taste thresholds (i.e. the minimum perceived concentration of a taste stimulus) and supra-threshold taste responses (perceived intensity and hedonics). This involves distinct methodological approaches in non-human primates and in humans.
... As for the diverging values at the lower end of the scale, such deviations are common in psychophysical experiments in which stimuli are presented in close temporal contiguity (Luce & Krumhansl, 1988), and they emerge also in the present experiment in which the downshifted test solution is compared to the memory of the training solution. The two lowest postshift solutions (0.5 and 1%) are so diluted that they either cannot sustain consummatory behavior or are close to the absolute lower threshold (Richter & Campbell, 1940;Sclafani & Nissenbaum, 1987). Recovery from reward downshift appears to involve further distortion of the function at both ends, depressing values in the lower end and increasing them at the higher end of the scale. ...
Article
Surprising downshifts from more preferred (training incentive) to less preferred incentives (test incentive) are usually accompanied by emotional activation and suppression of conditioned behavior in rats. Two experiments were designed to determine whether consummatory behavior is similarly affected by downshifts of equal proportions. Within limits, the degree of consummatory responding during incentive downshift was similar with equal ratios of test concentration to training concentration. Thus, 32–4% and 16–2% downshifts (1:8 test/training ratios) caused similar levels of consummatory behavior, despite differences in the absolute concentrations of the solutions involved in the downshift. An interpretation based on sensory contrast was discarded because of the long intervals between training and test solutions (40 min and 24 h in Experiments 1 and 2, respectively). It is suggested that Weber’s law regulates behavioral suppression after reward downshifts. A theoretical framework for the interpretation of these data is presented.
... A review by Mojet et al. (2001) uncovered a diverse range of different psychophysical procedures that have been adopted by researchers. For example, Richter and Campbell (1939) used the ascending method of limits and reported sucrose thresholds of 0.005 M, while Kunka et al. (1981) employed a transformed up-down staircase procedure and reported thresholds of 0.004 M. More recent studies have utilized paired-comparison forced-choice procedures (James et al. 1997) to examine gender (male = 0.0068 M; female = 0.0062 M) or the 2-AFC five-in-a-row method (Mojet et al. 2001) to examine age (young adult males = 0.015 M; young adult females = 0.011 M). ...
Article
This study attempted to measure absolute thresholds for sucrose in aqueous solution for 51 experienced judges. Two experiments utilizing the two-alternative forced-choice (2-AFC) procedure generated 6-point psychometric functions plotting percentage correct as a function of sucrose concentration. In both experiments, the judges were divided into two groups and tested in either purpose-built sensory booths or on open tables situated in a laboratory. In the first experiment, the influence of a confounding variable was apparent, with nonmonotonic psychometric functions being obtained. In experiment II, the confounding variable was eliminated, permitting the estimation of absolute thresholds. In both experiments, there was no main effect of gender or session, though there was an effect of testing locality (P < 0.05). Data are reported to emphasize the importance of controlling extraneous variables and to demonstrate the robustness of the 2-AFC procedure. This research contributes to an otherwise impoverished database on the detection of sucrose in a solution. The uses of the research include estimates of sucrose detection thresholds for comparative purposes; confirmation of the stability of the two-alternative forced-choice procedure; the utility of using formal testing areas as opposed to ad hoc testing stations; and the dangers of utilizing substandard experimental equipment while conducting research of this nature.
... Some complexity exists surrounding the influence of temperature on taste. Only small effects arising from temperature have been reported by some groups [36,41], possibly due to experimental differences, and the failure to separate contrasting effects of cooling and warming. The perception of taste is often described as following an upturned U shape with temperature [50]. ...
Article
Flavor is an essential, rich and rewarding part of human life. We refer to both physical and chemical heat in similar terms; elevated temperature and capsaicin are both termed hot. Both influence our perception of flavor, however little research exists into the possibly divergent effect of chemical and physical heat on flavor. A human sensory panel was recruited to determine the equivalent level of capsaicin to match the heat of several physical temperatures. In a subsequent session, the intensities of multiple concentrations of tastant solutions were scaled by the same panel. Finally, panelists evaluated tastants plus an equivalent amount in chemical or physical "heat". All basic tastes aside from umami were influenced by heat, capsaicin, or both. Interestingly, capsaicin blocked bitter taste input much more powerfully than an elevated temperature. This suggests that despite converging on similar perceptual responses, chemical and physical heat have a fundamentally different effect on flavor.
... The graded response sucrose EC50 of 243 mM is greater than has been determined previously. For example, the midpoints in an intensity scale for sucrose taste have been found to span 100 mM to 180 mM sucrose (Lawless and Skinner, 1979 (2006), but higher than the 12 mM value that has been reported in several other studies (Richter and Campbell, 1940;Pepino and Mennella, 2007;Joseph et al., 2016). However, there are differences in the assays across studies, and it should be noted that a large range of threshold values have been reported. ...
Article
The detection and grading of tastes corresponding to different taste modalities can be tested in engaging laboratory sessions using students themselves as test subjects. This article describes a series of experiments in which data pertaining to the detection of salty and sweet tastes are obtained, and the ability of the herb Gymnema sylvestre to disrupt the detection of sucrose is quantified. The effects of blinding and different assay designs on EC50 estimation are also investigated. The data obtained allow for substantial data analysis, including non-linear regression using fixed and free parameters to quantify dose-response relationships, and the use of often underutilized permutation tests to determine significant differences when the underlying data display heteroscedasticity.
Article
Thus, this brief account of our experiments has indicated that homeostasis may be maintained by “behavioral” as well as “physiological” mechanisms. How these two mechanisms probably operate and inter-react in intact organisms has been discussed elsewhere6, 7. It is hoped that this concept of “behavioral” mechanisms may be of use in the field of carbohydrate metabolism on the one hand to the experimenters who are working on animals, and on the other to the clinical workers on man. It should make the experimenters aware that animals themselves with their dietary selections and other forms of behavior may attempt to regulate carbohydrate metabolism; and the clinicians that patients may do likewise. It must be added that in man the operation of “behavioral” mechanisms may be complicated or confused by beliefs, habits, or social pressure.
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Article
Taste sensitivity was evaluated by suprathreshold scaling of six concentrations each of sodium chloride, sucrose, citric acid, and quinine hydrochloride. Magnitude estimation was used as the method of scaling. The study group was composed of 22 males and 19 females were either patients (institutionalized) or staff members of the Jewish Institute for Geriatric Care. Data from each patient were used to compute individual slopes and Y-intercepts of the log to log transformations for each solution sequence. The mean age of the persons who were institutionalized was significantly higher than that of the staff members. In addition, the mean age of the females was 10 years older than that of the males. The older adult males seemed to have impaired taste function that resulted in significant decreases in total perceived intensity of several taste solutions. No significant differences were shown in taste ability between the relatively healthy younger staff member subjects and the older, more infirm, institutionalized subjects.
Article
The taste and smell experience of other human beings cannot be known directly. Thus our understanding of age-related changes in the perception of taste and smell is derived inferentially. Inferences based on verbal reports and on the performance of tasks involving taste and smell stimuli suggest that some older individuals are impaired. The perceptual disadvantage of older adults appears to be more marked or more easily measured for complex than for simple stimuli. Some difference between older and younger adults may not be primarily sensory; others may arise from differences only incidentally associated with aging. The study of taste and smell perception in aging continues to challenge the psychophysical investigator to define the nature and extent of age-related change and to demonstrate its underlying mechanisms.
1.1. The effect of twenty-five sugars and related compounds on the feeding response of larvae of Spodoptera littoralis was investigated using the Styropor method.2.2. Styropor lamellae were treated with 0·25 and 0·0625 M solutions. The weight of the lamellae consumed and the number and weight of fecal pellets, served as criteria of feeding stimulation.3.3. Sucrose, raffinose, maltose, d-fructose, melibiose and d-glucose were found to be very active as phagostimulants.4.4. The survival of larvae which had fed on sugar-treated Styropor for 3 days was the longest on sucrose, maltose, glucose, fructose, raffinose and melezitose.5.5. Some of the sugars were assayed in pairs in different choice and no-choice experiments; no antagonistic or inhibitory effects were found.
Article
Sweetness is classically considered a single perceptual experience. However, diverse compounds can elicit this sensation, suggesting the existence of multiple pathways toward this end. This paper presents an overview of chemical theories of sweetness, reviews the phylogenetic and behavioral evidence for multiple pathways, and presents a summary of recent molecular advances regarding the sweet receptor. Potential sites for signal integration are discussed, and implications for nutritionists and food scientists are presented.
Article
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The taste responses to sweet and astringent compounds were investigated in two mammals of similar ecology, by using the classical method of the two-bottle test. The taste threshold for fructose was higher in Microcebus murinus, a prosimian primate, than in Caluromys philander, a didelphid marsupial. The profiles of suprathreshold responses resembled a dissymmetric bell-shaped curve, but the rate of consumption of sweet solutions up to maximal intake increased more rapidly in Microcebus than in Caluromys. Despite showing a photoperiod-synchronized physiology, Microcebus displayed no seasonal variation of the taste threshold and suprathreshold responses. The depressing effect of tanning acid on the ingestion of fructose solutions increased progressively with tannin concentration and was lower as fructose concentration increased. Inhibition thresholds for tannic acid were similar between the two species. The data suggest that adaptation to frugivorous diets is associated with globally similar shaping of the taste responses, even though subtle differences of palatability may account for differences of feeding selectivity.
Article
The response of the starling to sugar solutions was investigated as this species, which eats sweet fruits, does not prefer sugar solutions according to the literature. In choice tests using two identical fountains, moderate preference for higher concentrations (0.5 M and 1 M) of glucose and fructose to water was demonstrated. The same concentrations of sucrose were rejected. Lower concentrations (0.25 M and less) of all three sugars were neither preferred nor rejected. In choice tests using two differently coloured fountains the subjects did not generally respond more sensitively to sugar solutions. In learning experiments with differently coloured fountains the starlings developed very marked preferences for 0.5 M glucose and 0.5 M fructose and a corresponding rejection of 0.5 M sucrose in the course of 1–2 days. In a learning experiment with dentical fountains they also developed a pronounced preference; the preference values obtained, however, are higher if secondary cues such as the colour of the fountain or its position are available. In short time tests immediate responses to sugar solutions could not be demonstrated. The rejection of sucrose is attributed to illness-induced aversion learning, the learned preference for glucose and fructose to the preference according to gain in energy per unit of time as postulated by the optimal foraging theory. Taste sensations play, if any, only a minor role. The learning mechanisms operating in the experiments could be employed by the starling for the selection of fruits.
Chapter
Function of TasteUniversals in TasteNeuroanatomy of Taste SystemTaste LearningCurrent Trends and New Directions in Taste Research
Article
Responses of male wild (Cavia aperea) and domestic (C. Porcellus) guinea pigs to stimuli representing the taste qualities sweet, salty, sour and bitter were monitored in two bottle choice tests. Wild cavies showed statistically significant preferences for .008–.25 M NaCl and .001–.031 M sodium saccharin and rejected 1.0 M NaCl and .063 M citric acid. Domestic cavies' acceptances of solutions preferred by the wild form were lower on first series of presentations but increased to the level of C. aperea upon representations. C. porcellus rejected citric acid (.031 M), NaCl (.5 M) and sucrose octaacetate (.001 M) at concentrations not rejected by the wild type. Wild cavies did not reject SOA at any concentration and neither type rejected quinine sulfate. Absence of bitter rejection was postulated to be an adapatation useful to some herbivores. Changes in acceptance data over time and the interference of position preference with responses to solutions suggested the major difference between types to be the wild cavies' greater readiness to orient to stimulus cues.
Article
Preferences for NaCl, sucrose, HCl and quinine were examined in rats fed a diet containing D-penicillamine (D-pen), and compared with those of normal control rats. Preferences for NaCl and sucrose were reduced by administration of D-pen, and returned to normal upon cessation of D-pen administration. Change in preferences for NaCl and sucrose depended on the amount as well as the duration of D-pen administration. Preferences for HCl and quinine were unaffected by D-pen. No significant difference in the threshold and magnitude of the chorda tympani nerve responses to the taste stimuli was found between D-pen treated and normal rats. Concentrations of electrolytes in serum and saliva were scarcely changed by D-pen administration, but the amount of serum copper was markedly reduced. Effect of D-pen on sensitivity of taste receptors and role of copper ions in regulating fluid intake are discussed.
Article
The purpose of this long-term experiment was to determine if perinatal exposure to CNS activating drugs resulted in early and/or altered onset of aging, as measured by changes in preference for preferred concentrations of saccharin solutions. Seventy-nine primiparous Sprague-Dawley rats received twice daily subcutaneous injections of either 3.0 mg/kg or pure nicotine, 5.0 mg/kg of methamphetamine HCL, 5.0 mg/kg of saline vehicle, or no injections during the 21 day gestational period and during days 3–21 of the nursing period. Twelve male offspring were randomly selected from each treatment condition, and at six months of age, they were presented with a choice of 0.20, 0.10, 0.05, 0.025, 0.01, and 0.005% of saccharin in a tap water solution and plain tap water at three month intervals. Each concentration was paired with water and presented for a 48 hr period. Eight sessions were analyzed, which spanned the ages of months. Multivariate analyses revealed that: (1) The preference for individual saccharin concentrations across time differed as a result of maternal treatment. Differences were primarily due to the drug treatments and not to injection, (2) The pattern of saccharin preference changed over time as a function of maternal treatment but the overall level of saccharin consumption was not affected. These shifts were due to the drug treatments, not injection per se, (3) The total amount of saccharin solution consumed over time did not differ significantly among treatments, (4) The total amount of fluid consumed over the mature lifespan (saccharin solution plus water) decreased for all rats irrespective of maternal treatment. Other differences over time in total fluid consumption paralleled the saccharin index measures described above. Thus, perinatal treatment had a lasting effect upon preference for nonnutritive sweet solutions. The significance of this for aging organisms is discussed.
Article
Nectar is a solution of mainly three sugars: sucrose, glucose and fructose. Studies have demonstrated that pollinators have preferences according to the sugar composition presented in their diet, and these preferences may be caused by sugar assimilation capacities. However, sugar flavor could also play an important role for sugar preferences of nectar-feeding animals. We evaluated the sugar gustatory thresholds of the broad-billed hummingbird Cynanthus latirostris for sucrose, glucose, fructose and a 1:1 mixture of glucose-fructose. We presented eight C. latirostris to paired feeders containing either a sugar solution or pure water. Additionally, we conducted sugar preference tests at three different concentrations (146, 730 and 1022mmolL(-1)), to relate sugar preferences with sugar gustatory thresholds. C. latirostris had different gustatory thresholds for the three different sugars tested. At low sugar concentrations (146mmolL(-1)), sugar selection followed the gustatory thresholds. Hummingbird sugar preference patterns can be affected by different mechanisms, both pre- and post-ingestive. At low concentrations gustatory thresholds may play an important role to determine sugar selection. However, at intermediate and high concentrations, sugar assimilation rates, and velocity of food processing generated by osmotic constraints, can be the mechanisms that explain the sugar selection of these animals.
Article
Taste and smell are critical to dietary selection, especially for older adults, whose appetite is reduced. Neuroimaging studies can elucidate the process that causes the decrease of chemosensory functions with aging. The profound lost of olfactory functions in persons with Alzheimer disease accentuate the problem of inadequate food intake and disease progression.
Chapter
A complete assessment of nutritional status includes determination of dietary intake, anthropometric measurements, biochemical measurements, and clinical assessment. The state of the art in assessing nutrition status through each of these parameters has been reviewed recently by Kohrs and Czajka-Narins (1986). In interpreting data on the elderly, the advantages and limitations of the methods for dietary intake and anthropometric measurement need to be taken into consideration as well as the limitations of the current biochemical methods.
Thesis
Canonically, sweet perception is mediated by specific T1R2/T1R3 sweet taste G-protein coupled receptors expressed in taste cells of the tongue. However, mice lacking these receptors or their downstream signaling components are still able to recognize natural sugars. Conversely, they do not perceive artificial sweeteners, which are mostly canonical sweet taste receptor agonists, suggesting the existence of a parallel “alternative pathway” for sweet perception. To address the molecular pathways, complexity and physiological relevance of sweet taste sensation, this study combines a deep literature survey on sweet taste biology with experimental work using 3D cell cultures of immortalized human tongue cells (HTC-8). The literature research revealed that sweet-sensitive taste cells may take up monosaccharides via Glucose transporters (GLUT/SGLT1) to induce depolarization-dependent Ca2+ signals upon oxidative metabolism and KATP channel inactivation. Disaccharides can activate this signal path upon digestion from taste cell-expressed Brush Boarder enzymes. Alternatively, disaccharides may be taken up with elusive transporters, induce osmotic swelling and activate volume regulated anion channels. Via unidentified neuronal and/or endocrine mechanisms, sweet taste receptor-independent pathways may contribute to behavioral attraction but may also induce cephalic phase Insulin release upon GLP 1 secretion from taste cells. This would suggest that the alternative pathway may prepare the body for digestion, while the canonical pathway might be rather responsible for the hedonic value of sugars. Since taste differs among species and human samples are limited, most hypotheses of the alternative pathway remain rather vague and are often based on cells of other organs that express extraoral sweet taste receptors and canonical downstream molecules like gastro-intestinal or pancreatic cells. Since perfused live imaging experiments conducted in this study revealed that individual HTC 8 cells responded to KCl, sweet and bitter stimulation, they might belong to the newly described broadly-sensitive taste cells, which is in contrast with the assumption that diverse taste modalities use different signaling pathways in distinct cell types. A preliminary transcriptome analysis of HTC 8 spheroids corroborated the finding that taste is not exclusively transduced by the canonical pathway. Accordingly, bitter responses of HTC-8 spheroids might have been mediated by family members of the canonical signaling pathway, while sugars may have used the alternative pathway, since spheroids were not sensitive to the artificial sweetener Acesulfame K and related signal molecules of the alternative signal pathway were expressed upon 3D culture of HTC-8 cells. Although the here established model contains several limitations and needs further adjustment it might serve as a first testing platform to obtain human-derived data on taste physiology in a higher throughput than in human subjects. Thereby, it may support the search for new sugar alternatives and to combat the current sugar overconsumption which goes along with a sickening society.
Chapter
At any age, the perception of the taste and the odor of food has several important and basic contributions to the nutritional process for the individual. These chemical senses serve selective protective and stimulative functions for nutrition. The choice of food substances to be ingested is determined to a great extent by preferences for and aversions to foods. These choices are based on the learned pleasantness or unpleasantness a food has acquired to the senses of taste and smell. And these choices have been observed to become stubbornly resistant to change even in the face of modified nutritional needs at different stages in the life span. Young (1) indicated this in his statement: “new habits (in food consumption) tend to form in agreement with body needs, but established habits tend to persist as regulators of food selection even when the selections are out of the tune with bodily needs.” Cultural influences (2), cohort effects, (3,4), and specific familial experiences all serve to determine taste and odor preferences and aversions. By later life, these are well-ingrained determinants of nutritional behavior, and planning for changes in nutritional status in older adults that will be maintained necessarily includes gathering a detailed nutritional history that considers each of these factors.
Article
In presenting the material in this chapter, four fundamental propositions are made. These are: (1) Sucrose (sugar) tastes sweet. (2) Quinine tastes bitter. (3) Sodium chloride tastes salty 1. (4) Hydrochloric acid tastes sour.
Article
The sense of taste in conjunction with other senses plays a crucial role in decisions about whether a potential food will be accepted and swallowed or rejected, and it is intricately involved in ensuring that an organism consumes sufficient nutrients. In humans the chemosensory response to some sugars includes the perception of sweetness, which is almost universally described as a pleasant sensation. Thus for humans, and many other omnivorous and herbivorous species, sweet sugars are highly acceptable, stimulating ingestion (see Foman et al. 1983) and often preparatory reflexes for digestion as well (for review see Brand et al. 1982).
Article
Brazzein is a small, heat-, and pH-stable sweet protein present in the fruits of the West African plant Pentadiplandra brazzeana Baillon. It exists in two forms differing in sweetness intensity. The major form, called pyrE-bra, contains a pyroglutamic acid at its N-terminus, while the minor form, called des-pyrE-bra, lacks this residue. Here we describe the heterologous expression in the methylotrophic yeast Pichia pastoris of two natural forms of brazzein, pyrE-bra and des-pyrE-bra, and an additional form, called Q1-bra, which is not naturally occurring in the fruit. Q1-bra differs from pyrE-bra in having a glutamine residue instead of pyrE at its N-terminus. Over an expression period of 6 days, we obtained approximately 90, 30, and 90 mg/L of purified recombinant pyrE-bra, Q1-bra, and des-pyrE-bra brazzein forms, respectively. Recombinant proteins were purified and submitted to mass spectrometry and (1)H NMR spectroscopy. The data indicate that the recombinant brazzein forms were properly folded. Moreover, they activated the human sweet receptor in vitro and evoked sweetness in vivo with properties similar to those of the two natural brazzein forms.
Chapter
Feeding supplies are essential raw materials for the combined processes of maintenance, growth, and reproduction, in the majority of animals. On either side of this norm, however, are two extremes that represent adaptations to special conditions. One of the extremes is the insect in which feeding occurs for the prime, if not sole, purpose of providing energy for locomotion. There is no demand made by growth or reproduction. The male blowfly is an example of this adaptation. The adult blowfly, Phormia regina, is an insect that requires for its maintenance only water, carbohydrate, and oxygen. All other necessary materials are bequeathed by the larval stage. Except for the female during reproductive periods, there is no growth, not even wound healing. In the case of the blowfly, feeding is thus reduced to its lowest common denominator, and on the face of it, offers a simple system for analysis of two essential aspects of feeding— namely, the nature of the “on/off” mechanism and the nature of quality control.
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Conference Paper
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After the presentation of the general guidelines of actuation in sensorial control there comes the discussion of discriminatory tests, specially those related to the determination of threshold.
Chapter
This chapter takes a developmental approach in understanding sweet taste, presenting scientific evidence for the strong hedonic appeal of sweet taste and why children are particularly vulnerable to overconsumption of added sugars. Following a brief historical review on the industrialization of sugars and national guidance on dietary intake, we focus on the ontogeny of sweet taste and the biological mechanisms underlying sweet taste perception, highlighting classic experimental studies in the field as well as recent review articles. Age-related changes in two distinct psychophysical dimensions—the sensitivity of the taste system to sweet-tasting chemical stimuli and the hedonic valence of that sensation—can be measured reliably from an early age. Consequently, experimental research has revealed that both of these dimensions of sweet taste, as well as behavioral responses to sweetness, are inborn but change due to normal aging and dietary experiences. Because dietary patterns are established early, childhood is an important period for understanding how the biological and psychological factors underlying sweet taste sensations shape what children eat—the most important influence on health in modern societies.
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