Total Taste Intensity Research Articles

Gustatory sensation of l- and d-amino acids in humans

Amino acids are known to elicit complex taste, but most human psychophysical studies on the taste of amino acids have focused on a single basic taste, such as umami (savory) taste, sweetness, or bitterness. In this study, we addressed the potential relationship between the structure and the taste properties of amino acids by measuring the human gustatory intensity and quality in response to aqueous solutions of proteogenic amino acids in comparison to D-enantiomers. Trained subjects tasted aqueous solution of each amino acid and evaluated the intensities of total taste and each basic taste using a category-ratio scale. Each basic taste of amino acids showed the dependency on its hydrophobicity, size, charge, functional groups on the side chain, and chirality of the alpha carbon. In addition, the overall taste of amino acid was found to be the combination of basic tastes according to the partial structure. For example, hydrophilic non-charged middle-sized amino acids elicited sweetness, and L-enantiomeric hydrophilic middle-sized structure was necessary for umami taste. For example, L-serine had mainly sweet and minor umami taste, and D-serine was sweet. We further applied Stevens' psychophysical function to relate the total-taste intensity and the concentration, and found that the slope values depended on the major quality of taste (e.g., bitter large, sour small).

Effect of Arachidonic Acid-enriched Oil Diet Supplementation on the Taste of Broiler Meat.

To elucidate the relationship between the arachidonic acid (AA) content and the taste of broiler meat, the effects of AA-enriched oil (AAO) supplements on the fatty acid content and sensory perceptions of thigh meat were evaluated. Four types of oil, including corn oil (CO), a 1:1 mixture of AAO and palm oil (PO) (1/2 AAO), a 1:3 mixture of AAO and PO (1/4 AAO), and a 1:7 mixture of AAO and PO (1/8 AAO) were prepared. Each type of oil was mixed with silicate at a ratio of 7:3, and added to the diet at a final proportion of 5% of fresh matter. Broiler chickens were fed these diets for 1 wk before slaughter. In thigh meat, the AA content of the 1/2 and 1/4 AAO groups was significantly higher than that of the CO group. The AA content in thigh meat (y, mg/g) increased linearly with increasing dietary AAO content (x, g/100 g of diet), according to the equation y = 0.5674+0.4596× (r2 = 0.8454). The content of other fatty acids was not significantly different among the 4 diet groups. Sensory evaluation showed that the flavor intensity, umami (L-glutamate taste), kokumi (continuity, mouthfulness, and thickness), and aftertaste of the 1/2 and 1/4 AAO groups were significantly higher than that of the CO group. There were significant positive correlations between AA content in thigh meat and the flavor intensity, total taste intensity, umami, and aftertaste. These data suggest that the taste of broiler meat can be improved by the amount of dietary AA supplementation.

Supplemental arachidonic acid-enriched oil improves the taste of thigh meat of Hinai-jidori chickens

The Hinai-dori is a breed of chicken native to the Akita prefecture in Japan. A cross between the Hinai-dori and Rhode Island Red breeds has been commercialized as the Hinai-jidori chicken, one of the most popular brands in Japan. High arachidonic acid (AA) content is a characteristic feature of Hinai-jidori chicken meat. To elucidate the relationship between AA content and the palatability of the Hinai-jidori chicken, we examined the effects of palm oil (PO), corn oil (CO), and arachidonic acid-enriched oil (AAO) diet supplementation on the fatty acid content and sensory perceptions in thigh meat. Each oil and silicate was mixed at a ratio of 7:3, 5% of fresh matter was added to the finisher diet, and Hinai-jidori chickens were fed these diets for 2 wk before slaughter. In thigh meat, the AA content of the AAO group was significantly more than 2-fold higher than that of the PO and CO groups. Other fatty acid contents were not significantly different among the groups. Sensory evaluation showed that the total taste intensity, umami (l-glutamate taste), kokumi (continuity, mouthfulness, and thickness), and aftertaste of the AAO group were significantly higher than those of PO and CO groups in both chicken soup and steamed minced meat. These data suggest that the palatability of chicken meat can be improved by dietary AA supplementation.

Impact of various growing methods on tomato (Lycopersicon esculentum Mill.) yield and sensory quality

The effect of various growing methods of tomato (Lycopersicon esculentum Mill.) cv. Hector on fruit yield and sensory properties was examined. The growing methods used were: bare soil (BS), black plastic mulch (BPM), bare soil with polypropylene row cover (BS + RC) and black plastic mulch with polypropylene row cover (BPM + RC). The yields of all growing methods were reduced during growing season of extreme rainfall. The results show that the use of BPM + RC resulted in the highest total fruit yield (15.93 t ha-1). By using row cover (BS + RC or BPM + RC) it has been observed that marketable yield could be significantly higher than in the BS and the BPM treatments. Plants grown in the BPM and in the BPM + RC yielded larger number of fruits in comparison to plants in the BS or in the BS + RC. The fruit height and diameter were not affected by the treatments. This study also gives a sensory characterisation of various growing methods as an indicator of suitability for growing and marketing of tomatoes. Tomatoes grown in the BPM + RC resulted in the highest total taste intensity.

Investigation of Potential Taste Reduction of Catechin and Grape Seed Dimeric Phenols in Water by Wine Proteins

Soluble glycoproteins were isolated from Semillon wines made over a 5-y period, from 1990 to 1994, by precipitation with ammonium sulfate and fractionated by chromatography on Sephadex G-100. The total phenols were extracted with 50% aqueous ethanol from Semillon seeds, and the four seed phenol fractions (catechins, dimeric phenols, and oligomeric and polymeric tannins) were fractionated by diatomaceous earth partition chromatography of the total phenols. The proteins, catechin, and dimeric fraction alone appeared unchanged during storage in a wine-like model solution (aqueous 10% ethanol solution of pH 3.0) at 20 °C from 3 to 48 ch. However, the oligomeric and polymeric tannins, as well as the total phenols, gave rise to appreciable turbidity. The possible sensory effects of added proteins were investigated using paired comparisons between pure compounds (catechins and dimers) and the same compounds mixed with proteins. The hypothesis was that the proteins would decrease the taste of the catechins and dimers by decreasing their availability to interact with the taste receptors. Results corroborated the hypothesis when lower concentration of phenols and proteins were used. However, at higher concentrations, the reverse trend was observed. It is hypothesized that higher protein concentrations increased the total taste intensity by adding a taste of their own.

Sweet/sour balance in champagne wine and dependence on taste/odour interactions

Effects of sucrose and tartaric acid on the sweetness, sourness and total taste intensity of champagne wine were studied through a full factorial design including 15 samples, varying in sucrose (0g/l–20.5g/l) and tartaric acid (2.50g/l–4.22g/l). Two experiments, involving 10 selected and trained subjects, were performed. Samples and procedures were the same, except that subjects had their nostrils closed with nose-clips in experiment 2. The suppressive effect of sucrose on the sourness of tartaric acid was stronger in experiment 2. The suppressive effect of tartaric acid on the sweetness of sucrose was very low in both experiments. Applying the vector addition model on total taste intensity scores indicated that sucrose and tartaric acid partially suppressed each other in both experiments. Sweetness contributed to a greater extent in the judgement of total taste intensity, particularaly in the nose-clip condition.

Sweetness, Sourness, and Total Taste Intensity in Champagne Wine

Fifteen wines, varying in sucrose (0 g/L, 5 g/L, 8 g/L, 12.8 g/L, and 20.5 g/L) and tartaric acid (2.50 g/L, 3.25 g/L, and 4.22 g/L) were prepared according to a full factorial design from an unsweetened base Champagne wine. Ten selected and trained subjects rated sweetness, sourness, and total taste intensity of the entire set of wines in triplicate. The suppressive effect of sucrose on the sourness of tartaric acid was stronger than the suppressive effect of tartaric acid on the sweetness of sucrose. Total taste intensity scores indicated that sucrose and tartaric acid exhibited poor additivity and partially suppressed each other. An integration of sweetness and sourness in the global intensity percept was observed. Sweetness contributed to a greater extent in the judgment of total taste intensity in Champagne wine.

TIME INTENSITY PROFILES OF FLAVOR POTENTIATORS (MSG, IMP, GMP)

ABSTRACTThis research characterized the time‐intensity (TI) profiles of monosodium glutamate (MSG), disodium 5′‐inosinate (IMP), and disodium 5′‐guanylate (GMP). Twenty subjects rated total taste intensity of single solutions of 2.5, 5 and 10 mM MSG, 0.63 and 2.5 mM IMP and GMP, and some of their mixtures, using the TI method. The profiles generated were atypical of other taste modalities. Time to maximum intensity waslong (16–20s), followed by a plateau at maximum intensity, and a persistent aftertaste (50–96s duration). Maximum intensities of the samples varied (p < 0.001), with mixtures of 10 and 5 mM MSG with 2.5 mM IMP or GMP yielding the highest intensities. Similar differences were found for total duration and area under the curve. These results indicate that flavor potentiators may increase total flavor during consumption. Synergism between flavor potentiators was demonstrated.

Reduction of saltiness and bitterness after a chlorhexidine rinse.

Chronic rinsing with chlorhexidine, an oral-antiseptic, has been shown to decrease the saltiness of NaCl and the bitterness of quinine. The effect of acute chlorhexidine on taste has not been investigated. The purpose of the present study was to examine the effect of acute chlorhexidine rinses on taste intensity and quality of 11 stimuli representing sweet, salt, sour, bitter and savory. All stimuli were first matched for overall intensity so the effects of chlorhexidine would be directly comparable across compounds. As a control treatment, the bitter taste of chlorhexidine digluconate (0.12%) was matched in intensity to quinine HCl, which was found to cross-adapt the bitterness of chlorhexidine. Subjects participated in four experimental conditions: a pre-test, a quinine treatment, a chlorhexidine treatment, and a post-test condition, while rating total taste intensity and taste qualities in separate test sessions. Relative to the quinine treatment, chlorhexidine was found to decrease the salty taste of NaCl, KCl and NH4Cl, and not to significantly affect the tastes of sucrose, monosodium glutamate (MSG), citric acid, HCl and the taste of water. The bitter taste of urea, sucrose octa-acetate and quinine were suppressed after chlorhexidine rinses relative to water rinses, but were only marginally suppressed relative to quinine rinses. Potential mechanisms are discussed.

Effects of altered ration levels on sensory characteristics, lipid content and fatty acid composition of rainbow trout ( Oncorhynchus mykiss)

This study describes the effects of altered ration levels on sensory characteristics, lipid content and fatty acid composition of rainbow trout fillet. Ration levels were altered from adequate to restricted level after 0.2 and 1.0 years from hatching and from strongly restricted and restricted levels to adequate level 1.0 years from hatching. A selected and trained panel carried out descriptive sensory tests on fish fillet cross-sections. The intensity of total odour increased, and that of juiciness decreased with age, independent of ration level. Ration level had an overall effect on the total taste intensity, independent of age. Fresh odour correlated negatively to the saturated fatty acids 14:0 ( r=−0.834; p<0.001), 16:0 ( r=−0.831; p<0.001) and 18:0 ( r=−0.668; p<0.05). Trout that had their ration level altered from restricted to adequate level 1.0 years after hatching had a higher lipid content than trout having their ration level altered from adequate to restricted level after 0.2 and 1.0 years, respectively. Including fillet lipid content in the statistical model indicated that lipid is an important factor decisive for total taste and flesh texture of the trout. Fish having their ration level altered from adequate to restricted level after 0.2 years had a significantly lower condition factor than fish having it altered 1.0 years after hatching.

The addition of CO2 to traditional taste solutions alters taste quality.

Previous studies of the effect of carbonation on taste perception have suggested that it may be negligible, manifesting primarily in increases in the perceived intensity of weak salt and sour stimuli. Assuming CO2 solutions in the mouth stimulate only trigeminal nerve endings, this result is not altogether surprising; however, there are neurophysiological data indicating that CO2 stimulates gustatory as well as trigeminal fibers. In that case, carbonation might alter the quality profile of a stimulus without producing substantial changes in overall taste intensity--much as occurs when qualitatively different taste stimuli are mixed. To address this possibility, subjects were asked to rate the total taste intensity of moderate concentrations of stimuli representing each of the basic tastes and their binary combinations, with an without added carbonation. They then subdivided total taste intensity into the proportions of sweetness, saltiness, sourness, bitterness and 'other taste qualities' they perceived. The addition of carbonation produced only small increases in ratings of total taste intensity. However, rather dramatic alterations in the quality profiles of stimuli were observed, particularly for sweet and salty tastes. The nature of the interaction is consistent with a direct effect of carbonation/CO2 on the gustatory system, although the possibility that at least some of the observed effects reflect trigeminal-gustatory interactions cannot be ruled out.

Amiloride Suppresses the Sourness of NaCl and LiCl

The transduction of Na+ salts in many species is mediated by both apical and submucosal ion channels on the taste receptor-cell membrane. The apical ion channel is blockable by the diuretic amiloride, whereas the submucosal pathway is not. Previous human psychophysical studies have shown a decrease in NaCl taste intensity caused by amiloride that is smaller than the reduction of the electrophysiological response produced by amiloride in other species. Many salts, including NaCl, elicit not only a salty taste to humans, but also sweet, sour, or bitter side tastes. Amiloride has been shown to reduce the sourness, but not the saltiness, of NaCl and Na gluconate and to have no effect on the taste of KCl. The present experiment further evaluated the hypothesis that the sour taste of Na+ and Li+ salts is mediated by the amiloride-sensitive transduction mechanism, by examining the effect of amiloride on the taste of LiCl, which is considerably more sour than NaCl. Four concentrations of NaCl, LiCl, and KCl were presented to the anterior tongue following adaptation to water or after 10 μM amiloride treatment. Subjects estimated the intensity of the taste of each stimulus and divided this estimate among the appropriate taste qualities. There was a significant decrease in the total taste intensity of NaCl and LiCl after amiloride, but no effect on KCl; LiCl was more greatly suppressed than NaCl. These data show no effect on the saltiness of LiCl or NaCl, except for a small reduction in the saltiness of 0.1 M NaCl. On the contrary, there was a significant effect on the sourness of both NaCl and LiCl. Citric acid (3.2 mM) was also used as a stimulus, but amiloride treatment had no effect on its sourness. These data indicate that the amiloride-sensitive channel plays a key role in the perception of the sour taste of NaCl and LiCl (but not citric acid) and little role in the perception of saltiness. The salty taste of these salts may arise from other transduction pathways.

Determinants of cumulative successive contrast in saltiness intensity judgments.

When all stimuli elicit the same taste quality, solutions preceded by a high concentration level are judged to be significantly less intense than solutions preceded by a low concentration level. After repetitious stimulation with a different tasting stimulus, the intensity of the present stimulus is over-estimated. This phenomenon is called "successive contrast." In the present study, the cumulative effects of three identical stimuli on the saltiness ratings for a test stimulus are investigated. The preceding stimuli are manipulated with regard to taste quality, saltiness intensity, total taste intensity, and complexity. Whether the size of the cumulative contrast effect is associated with the degree of dissimilarity between preceding stimuli and test stimulus, or with the saltiness or total taste intensity of the preceding stimuli, is investigated. The size of the contrast effect depends on the type of preceding stimulus, its intensity, and the type of test stimulus. No association was found with judgments of the degree of dissimilarity between the preceding stimuli and the test stimulus. For nonsalty preceding stimuli, the contrast effects are independent of concentration level. When the preceding stimuli taste at least partly salty, the total intensity appears to determine the size of the contrast for an unmixed salty test stimulus.

Effect of amiloride on the taste of NaCl, Na-gluconate and KCl in humans: implications for Na+ receptor mechanisms.

Sodium-salt transduction in many species may be mediated by both apical and submucosal ion channels on the taste receptor cell membrane. The apical ion channel is blockable by the diuretic amiloride, whereas the submucosal pathway is not. Sodium salts with small anions, such as NaCl, can stimulate submucosal as well as apical ion channels; sodium salts with large anions, such as Na-gluconate, activate primarily the apical channels. In humans, reports on the effects of amiloride on the taste of NaCl are conflicting and no data exist on the effects of amiloride on organic sodium salts. In the present experiment, subjects gave magnitude estimates of the total intensity and of each of the basic taste qualities for NaCl, Na-gluconate and KCl. Five concentrations of each of these stimuli were presented to the anterior tongue following distilled water adaptation and after amiloride treatment. There was a significant decrease in the total taste intensity of NaCl and Na-gluconate after amiloride, but no effect on KCl. The saltiness of all three salts was unaffected, but amiloride decreased the perceived sourness of the sodium salts. KCl sourness was unaffected by amiloride. There was a proportionately larger effect of amiloride on Na-gluconate than on NaCl, which is consistent with a larger role for the apical ion channel in Na-gluconate transduction. However, an appreciable amiloride-insensitive component is present for both NaCl and Na-gluconate, suggesting that an amiloride-insensitive pathway also plays a role in the transduction of both sodium salts. These data support the hypothesis that an amiloride-sensitive transduction component exists in humans, but suggest that it is considerably smaller than in many other species.

Perceptual integration in heterogeneous taste percepts.

When mixtures of dissimilar tasting compounds are perceived, specific taste sensations are integrated into a percept. Four models are evaluated that were designed to predict the total taste intensity of a mixture percept from the total taste intensities of the unmixed components or from the specific taste intensities of the components within the mixture percept. The predictions of the two dominant component models are inferior to those made by the two other models. Predictions made by the vector summation model are accurate, but the model contains theoretical weaknesses that make it an invalid psychological integration model. The sum of sensations model predicts total intensity with an accuracy similar to the vector summation model, but it is more parsimonious. Furthermore, it can account for all of the empirical phenomena observed.

Interrelationships among sweetness, saltiness and total taste intensity of sucrose, NaCl and sucrose/NaCl mixtures

A proper description of the taste interaction in mixtures requires that scale values are assessed on response scales which are linear with perceived taste intensity. In the present study, the interrelationships among the sweetness, saltiness and total taste intensity of unmixed sucrose, unmixed NaCl and mixtures of sucrose and NaCl were studied according to a conceptual scheme that formalizes the interrelationships among different psychological constructs involved in the research of mixtures of dissimilar tasting substances. The scale values of perceived sweetness, saltiness and total taste intensity were assessed using a functional measurement approach in combination with a two-stimulus procedure. The results showed that the scale values obtained were linear with perceived taste intensity. The two most important results were that (i) the perceived total taste intensity of a sucrose/NaCl mixture could be well predicted by the square root of the sum of the squared intensities of the taste intensities of the unmixed components of the mixture, and (ii) the perceived total taste intensity of a sucrose/NaCl mixtures was approximately equal to the sum of the perceived sweetness intensity of the mixture and the perceived saltiness intensity of the mixture. The results of the present experiment are compared with the results of previous studies.