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While examining the taste of various proteins, we found that hen egg-white lysozyme, a bacteriolytic enzyme, had sweetness. Lysozymes from other sources such as turkey and soft-shelled turtle also showed sweetness with different tastes, heavy or light. In contrast, human lysozyme was tasteless. The amino acid sequences of the various lysozymes were similar to that of hen lysozyme, but hen lysozyme did not show significant homology to sweet proteins.
Patients with localized damage to the taste system often experience no subjective change in real-world taste experience. In an effort to understand this, eight patients who recently underwent acoustic neuroma removal were evaluated for taste loss. Localized taste testing showed that taste intensities decreased in the distribution of cranial nerve VII ipsilateral to tumor removal as expected, but asymmetries occurred for IX. Intensities were greater on the side contralateral to the tumor removal. In addition, palatal taste, also thought to be mediated by VII, was not totally abolished. It is concluded that cranial nerve IX is normally inhibited by cranial nerve VII in the taste network. When VII is damaged, this inhibition is abolished. This release of inhibition serves as a compensation mechanism that preserves normal taste experience.
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It was hypothesized that subjects with chronic obstructive pulmonary disease (COPD) receiving long-term oxygen via nasal cannulas have an impaired sense of smell and/or taste. To objectively evaluate the sense of smell and taste, this study used the University of Pennsylvania Identification Test (UPSIT), a 40-item "scratch-n-sniff" test and a 20-item taste test using the four basic taste sensations of sweet, salt, sour, and bitter. Twenty subjects (15 male, 5 female) with severe COPD receiving long-term oxygen therapy (group 1), and an equal number of age- and sex-matched subjects with COPD not receiving oxygen therapy (group 2), and a healthy control group (group 3) were studied. Twelve subjects (seven male, five female) from group 1 subsequently underwent transtracheal oxygen catheter installation. Mean +/- SD for the basic smell test was significantly greater in group 3 (35.35 +/- 3.58) as compared with group 1 (27.70 +/- 6.07) or group 2 (31.10 +/- 4.95) (p less than 0.005). The difference between group 1 and 2 was not significant (p = 0.066). However, when adjusted for pack years of smoking, there were no significant differences between the three groups. Mean +/- SD correct responses for the basic taste test were significantly greater in group 3 (15.75 +/- 1.81) as compared with group 2 (12.8 +/- 2.78) (p less than 0.005) and group 1 (14.00 +/- 2.33) (p less than 0.05). There was no significant difference between group 1 and 2. The corrected data for taste, adjusted for years since quitting smoking, did not alter the basic differences between the groups. Mean smell and taste test scores were essentially unchanged in 12 subjects after six months of transtracheal oxygen therapy. Long-term oxygen use via nasal cannulas in this group of subjects with COPD did not appear to impair their sense of smell and taste. Smoking had a significant but variable effect on the sense of smell and taste.
C57BL/6ByJ (B6) and 129P3/J (129) mice have different alleles of Tas1r3, which is thought to influence gustatory transduction of sweeteners, but studies have provided conflicting results regarding differences in sweetness perception between these strains. Single-unit taste-evoked activity was measured in the nucleus of the solitary tract (NST) in anesthetized B6 and 129 mice to address this controversy and to provide the first electrophysiological characterization of this nucleus in mice. Neurons had properties similar to those of NST cells in other species, including mean breadth-of-tuning of 0.8 +/- 0.0. There were no strain differences in neural responses at 600 or 900 ms after onset, but, with a 5 s evoked period, responses to the sweeteners sucrose, maltose, acesulfame-K, SC-45647, and D-phenylalanine were significantly larger in B6 relative to 129 mice. The strains did not differ in their mean response to NaSaccharin, but it evoked an across-neuron pattern of activity that was more similar to that of sucrose and less similar to that of NaCl in B6 mice compared with 129 mice. Neurons were classified as sucrose, NaCl, or HCl responsive, with the former more common in B6 than 129 mice. Relative to other neurons, sucrose-responsive cells had delayed but more sustained sweetener responses in both strains. The results suggest that B6 mice perceive some sweeteners as more intense, but NaSaccharin as sweeter and less salty, relative to 129 mice. Furthermore, activity evoked by sweeteners includes a phasic response sent to different NST cells than a later tonic response, and only the latter differs between B6 and 129 mice.
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Earlier psychophysical research on single human fungiform taste papillae employed a procedure which limited subjects to selecting only one taste to describe the sensations they experienced. That procedure precludes the possibility of determining whether single papillae can mediate complex tastes, i.e., tastes consisting of more than one sensation experienced simultaneously. By using highly trained subjects and allowing them freedom to describe all sensations simultaneously elicited by a given taste stimulus, single papilla taste profiles were obtained. It is suggested that obtaining taste profiles may increase the utility of single papillae as models for study of the taste system.
Egyptian spiny mice (Acomys cabirinus) were tested for drinking preferences by means of Richter-type tests (sapid solution versus distilled water). The subjects were 7 male and 7 female adults which were individually housed within an environmental chamber. Solutions used in the tests were concentrations of 5 common sugars (.005 M to 1.0 M), 3 salts (.005 M to 1.0 M), and 2 acids (4.0 pH to 1.5 pH). The molar range was too limited to identify the most preferred concentrations of fructose and glucose, but preferences for lactose, maltose, and sucrose appeared to occur at peak levels within the range. None of the salts (Kcl, MgSO4, and NaCl) was preferred over water in any of the tests, and both acids, the organic more than the inorganic, were rejected in all tests. The findings were contrasted with results from Richter-type tests conducted with other species of rodents.
Taste sensitivity for sodium chloride in solution and sensitivity and preference for sodium chloride in bread were measured in 14 male patients undergoing hemodialysis. There was an increase in sensitivity to salt taste following dialysis only when assessed using the bread samples. Patients on a lower sodium diet were more sensitive to salt taste in bread. Although the taste changes were not related to the decreases in serum sodium or to copper, greater increases in sensitivity were related to greater increases in serum zinc during dialysis.
The ability of denatonium saccharide (DS) to function as an aversive stimulus for the rat was studied in a conditioned taste-aversion paradigm in two experiments. Exp. 1 assessed the effects of DS during a 30-min. access period when only a saccharin solution was available. Exp. 2 assessed the effects of DS during both a 10- and a 30-min. access period when a saccharin solution and free water were available. The results showed that DS did not attenuate saccharin consumption reliably over all test days. The effect was most apparent during the 10-min. interval when free water was available. These results, together with previous reports, suggest that DS appears to function as a weak aversive stimulus in the rat.
Depressive patients often complain about dullness of taste of previously liked food items as well as of persistent bad taste. Taste and smell experience can be reflected by cognitive (psychophysical) indicators and also by reflectory (facial expressive) responses. In the present study 21 depressed, hospitalized patients and 16 control subjects were exposed to food-related gustatory and olfactory stimuli. Psychophysical and videotaped facial reactions were recorded from both groups. Analysis indicated that cognitive estimates of taste hedonics were similar for depressed and control groups; the former responded to sweet taste with a shorter-lasting facial reaction, involving markedly fewer facial features expressing enjoyment, than did controls. Aversive tastes, in contrast, triggered comparable facial expressive features of disgust in both groups. Facial reactions of depressed patients to acceptable and aversive olfactory stimuli were all significantly shorter and more muted than those of controls. Facial reflexes triggered by chemical cues are known to be controlled primarily by brainstem structures. Present findings suggest a possible influence of the profound anhedonia of severe depression on subcortical processes.
Successive negative taste contrast in humans was demonstrated with a common taste stimulus, i.e., cherry-flavored Kool-Aid. A total of 31 male and female college-aged participants rated a 7% sucrose solution which was cherry-flavored as less sweet when it was preceded by a 28% rather than a 7% sucrose solution which was cherry-flavored. Because drugs such as the benzodiazepines affect taste contrast in rats and act as anxiolytics in humans, the present experiment also examined whether several self-reported measures of anxiety were related to taste contrast in humans. Neither scores on Taylor's Manifest Anxiety Survey nor those on the State-Trait Anxiety Inventory were related to "sweetness" ratings or contrast effects.
Pleasantness and intensity ratings of beverages served in containers congruent and incongruent with expectancy were assessed. Past research has shown that the violation of food expectancies, e.g., color, taste, temperature, leads to more negative evaluations of food. Thus, it was hypothesized that beverages sampled from a container incongruent with expectancy, e.g., beer from a coffee cup, would be rated less favorably than the same beverage sampled from a container congruent with expectancy, e.g., beer from a beer bottle. 61 participants evaluated three beverages (beer, orange juice, and hot chocolate) in three containers (bottle, glass, and cup) using 11-point rating scales for pleasantness and intensity. Analysis indicated beverages were rated as significantly more pleasant in containers congruent with expectancy, as well as rated more intense when presented in bottles. These results further address the effects of violating expectations on producing negative hedonic evaluations.
Two-bottle tests of solution acceptance were conducted in an outdoor aviary with eight common ravens (Corvus corax). Aqueous concentrations of the following chemicals were used: five common sugars, three salts, two acids, quinine hydrochloride, and sodium saccharin. Solution acceptance, as recorded for the different ravens on each test, was the percentage of preference shown for a test solution over water (comparison solution). Mid-range saccharin concentrations (0.10% to 0.80% [w/w]) were preferred over water in the tests. The preference for saccharin contrasts with all other reports on avian response to the chemical in two-bottle tests. Nonetheless, the ravens nonpreferentially accepted lower concentrations or were averse at higher concentrations to drinking sugar solutions. Similar, though more sharply marked, shifts from indifference to aversion were noted in tests with the other chemicals. The possible relevance of these latter findings to the food habits of ravens is discussed.
A prognostic study was performed in 197 consecutive cases of Bell's palsy. The patients were investigated soon after onset, after one week, after one month and then every second month until total recovery or one year had elapsed. Case histories, clinical findings, and laboratory data were noted. Facial EMG, pure tone audiometry, stapedius reflex test and electrogustometry were performed. The healing time, quality of final healing and amount of sequelae were noted. All data were fed to a computer and correlations were calculated. The final degree of healing was well correlated to the initial EMG, the stapedial reflex test and the electrogustometry but also to the clinical evaluation of the degree of motility at the first visit. A combination of EMG, electrogustometry, stapedial reflex test and evaluation of lacrimation showed a high rate of prognostic value.
The relationship between the size of the stimulated human tongue area, the stimulating electric current intensity and the provoked sensory qualities was examined. Five different electrode areas and four anodal current intensities were used. The observed sensations were of three kinds: sour taste, somatosensory, and undefined ones. At a given current intensity level the proportion of taste increases with the increase in the stimulation area, while somatosensory sensations decrease. These results imply that at the suprathreshold level there is a certain interdependence between the area, current intensity and sensory effects. In order to achieve optimal activation of the taste system alone, it is more effective to use a larger electrode and stronger current, than to use smaller areas and weaker stimuli: in this case the electrical sour taste is satisfactorily clear, since the somatosensory system is still not activated. These findings may have implications in clinical electrogustometry.
Many previous attempts to acquire gustatory evoked potentials (GEPs) in both men and animals could not satisfy strict requirements on purely unimodal stimulation free of contaminating artifacts. Therefore we developed an advanced new gustometer, based on our previous experience on olfactory evoked potentials, especially on magnetic valves as also used in our "Erlangen olfactometer". Several newly constructed magnetic valves were tested; the best one (MV3) enables us to fulfill the following indispensable conditions for proper averaging by computer: precise onset and duration of stimulus, and shortest possible stimulus rise and fall times. Tactile artifacts were avoided by constant rinsing of the tongue with neutral water, in which the taste stimulus was embedded without turbulences. By recording and averaging the galvanic skin response (GSR) at the same time, its influence on GEPs was compensated. To evaluate successfully objective correlates of taste sensation in man is believed to be of great basic and clinical importance.
The US population is aging rapidly and, within the next 25 years, 20-25% will be over age 60. This creates a vast new market for age-specific products and increases the responsibility of food scientists and nutritionists to provide appropriate foods for older adults. Many older individuals are energy deficient and need to be encouraged to consume more food in order to maintain body weight and health, but need to decrease the calories from fat in their diets. Many of these older individuals are not inclined to eat foods that they enjoy for fear that these foods may be detrimental to their health (de Castro, 1993), or they have lost their gustational abilities to the degree that these foods are no longer enjoyable. This research looks at a possible solution to both problems by replacing fat in a favorite food of older adults and adjusting the flavor levels of this product. Frankfurters were made from mechanically deboned poultry meat in which standard commercial formulation was compared to three flavoring treatments using oat bran as a fat replacer (6% oat bran, 30% H2O). Mixed spices (traditional saucisson) were added to two of these treatments in standard and double proportions. Participants were 71 individuals over the age of 65 in varying levels of health from four regional care facilities. Seven gram, three-digit-coded samples were evaluated at 60 degrees C, and scored on a nine-point hedonic scale. A significant (alpha = 0.0004) preference was shown for the double-spiced frank. No differences by sex or race were found. Research concluded that addition of flavoring aids in the increased acceptability of products by older adults.