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.     

Inheritance of taste components in tomato

Components of tomato taste can be modeled from a set of instrumentally measured parameters. The inheritance was studied of two texture parameters with an effect of mealiness and pleasantness of taste: BFp and EBp. A recombinant inbred line population (F6) of the cross tomato cv Moneymaker x L. pimpinellifolium was analyzed for these parameters, and a molecular linkage map was developed for this population. A single QTL region on chromosome 9 was found with an effect on both BFp and EBp. The QTL explained 18.2 and 18.8% of the population variances, and 19.5 and 39.0% of the parental differences respectively for BFp and EBp.     

Successive contrast cannot explain suppression release after repetitious exposure to one of the components of a taste mixture

Repetitious exposure to one of the components of a NcCl-sucrosemixture causes the other component to recover from suppression.This so-called‘suppression release’ might be explainedby assuming that the subjects habituate to the repeated component,which is thereby disabled as a suppressor in the mixture. Twoexperiments are reported that test successive contrast as analternative explanation of this type of suppression release.This alternative was investigated by substituting an unmixedtest stimulus of about equal subjective sweetness (or saltiness)for the mixture. The results indicate that successive contrastcontributes only partially to the suppression-release effect.When the contrast contribution is subtracted, a significantsuppression-release effect remains.     

Temporal properties of the human taste system.

An attempt to apply linear systems methods to the temporal properties of the human taste system is described. The percentage modulation in concentration required to detect a fluctuation in intensity was measured as a function of frequency of modulation. Both a sine-wave and a square-wave input were used. The sensitivity of the taste system at its maximum, and also at the low frequencies, was greater than expected from previous work based on classical methodology. The sensitivity of the taste system at its maximum, and also at the low frequencies, was greater then expected from previous work base on classical methodology. The sensitivity of the taste system to the various qualities was, in decreasing order, salty, sweet, sour, and bitter. The taste system in insensitive to frequencies above about 5 Hz. Except for bitter, representatives of the various taste qualities yielded similar functions within qualities.     

Temporal synchrony and integration of sub-threshold taste and smell signals

The importance of stimulus timing and location on the perceptual integration of taste and odour was studied based on a sub-threshold methodology. From a panel of 16 people, 12 showed the integration effect previously reported while 4 showed no effect. The experiment was repeated using retronasal and orthonasal delivery of the odour and with tastant present or absent in the mouth. Integration of taste and odour only occurred when both stimuli were present at the same time. Retro- or orthonasal presentation both produced integration providing that tastant delivery was synchronous but the threshold values for the two presentation methods were different. The relevance of these findings to flavour perception under realistic conditions is considered.     

Physiological responses to taste signals of functional food components

The functions of food have three categories: nutrition, palatability, and bioregulation. As the onset of lifestyle-related diseases has increased, many people have shown interest in functional foods that are beneficial to bioregulation. We believe that functional foods should be highly palatable for increased acceptance from consumers. In order to design functional foods with a high palatability, we have investigated about the palatability, especially in relation to the taste of food. In this review, we discuss (1) the identification of taste receptors that respond to functional food components; (2) an analysis of the peripheral taste transduction system; and (3) the investigation of the relationship between physiological functions and taste signals.     

Temporal changes in NCAM immunoreactivity during taste cell differentiation and cell lineage relationships in taste buds

Neural cell adhesion molecule (NCAM) is a type III cell marker in the taste buds. In order to clarify the cell type of Mash1-expressing cells in taste buds, expression of NCAM was examined in Mash1-expressing taste cells of adult mice in comparison with gustducin- and T1r3-expressing cells, using a combination of NCAM immunohistochemistry and in situ hybridization. About 98% of Mash1-expressing cells were NCAM immunopositive (IP), suggesting that Mash1-expressing cells should be categorized as type III cells. Unexpectedly, small subsets of gustducin- and T1r3-expressing cells were also found to be NCAM-IP, contradicting previous immunohistochemical studies in rats, in which gustducin-IP cells were observed specifically in type II cells, which do not have NCAM immunoreactivity. Examinations of developing taste buds showed temporal changes in the ratio of NCAM-IP cells in gustducin- and T1r3-expressing cells; the ratio of NCAM-IP cells in these gene-expressing cells were approximately 90% at 0.5 days after birth and decreased markedly during development. In contrast, the majority of Mash1-expressing cells showed constant NCAM immunoreactivity throughout development. In addition, BrdU-labeling experiments showed that the differentiation of Mash1-expressing cells precedes those of gustducin- and T1r3-expressing cells in taste buds of adult mice. These results suggest that T1r3- and gustducin-expressing cells are NCAM-IP at the beginning of cell differentiation, and that NCAM immunoreactivity in gustducin- and T1r3-expressing cells might remain from the previous developmental stage expressing Mash1.     

Spatial dissociation of early and late colour evoked components

Evoked potentials to the primary colours red, green, yellow and blue were recorded and compared with those evoked by white. The unpatterned 10° × 13° stimuli were generated with the aid of a colour monitor. Activity was depicted with 5 electrodes, the central electrode 5 cm above the inion and two on each side 5 and 10 cm apart from the central electrode.With equally bright colour stimuli a previously described early negative colour-dominated component N87 was localized in all subjects at the central occipital electrode while the following positivity P100 was clearly more lateralized to the peripheral electrodes. With half-field stimulation N87 showed a similar — paradoxical — lateralization to the ipsilateral electrodes as has been demonstrated for pattern reversal.The existence and localization of N87 could be confirmed also for blue colours, its amplitude independent of the blue luminance, its latency decreasing for definite additional brightness increments and decrements. The N87 to blue was of the same latency as the N87 components to other colours.N87 is mainly generated foveally and parafoveally, its amplitude saturates with stimuli larger than 6–8° in diameter.     

Binary taste mixture interactions in prop non-tasters, medium-tasters and super-tasters

It is generally assumed that the mutual, but asymmetric, suppression of the components in binary taste mixtures is an invariant property of the human psychophysical response to such mixtures. However, taste intensities have been shown to vary as a function of individual differences in sensitivity, indexed by the perceived bitterness of 6-n-propylthiouracil (PROP). To determine if these variations in taste perception influence taste mixture interactions, groups of PROP super-, medium- and non-tasters assessed four binary taste mixtures: sweet-bitter [sucrose/quinine hydrochloride (QHCl)], sweet-sour (sucrose/citric acid), salty-bitter (NaCl/QHCl) and salty-sour (NaCl/citric acid). In each experiment, subjects received factorial combinations of four levels of each of two tastants and rated individual taste intensities and overall mixture intensity. For each taste quality, super-tasters typically gave higher ratings than either medium- or non-tasters, who tended not to differ. There were also group differences in the interactions of the mixtures' components. Super-tasters rated the overall intensity of the mixtures, most likely reflecting integration of the taste components, as greater than medium- and non-tasters, who again showed few differences. In sweet-bitter mixtures, non-tasters failed to show the suppression of sweetness intensity by the highest QHCl concentration that was evident in super- and medium-tasters. These data show that the perception of both tastes and binary taste mixture interactions varies as a function of PROP taster status, but that this may only be evident when three taster groups are clearly distinguished from one another.     

The validity of the equiratio taste mixture model investigated with sorbitol-sucrose mixtures

The equiratio taste mixture model developed and shown to bevalid for glucose-fructose mixtures was investigated in orderto assess its applicability to two-component mixtures of othersweet substances. A magnitude estimation experiment using thesip and spit procedure determined psychophysical functions forsorbitol, sucrose and three equiratio sorbitol-sucrose mixtures.Mixture functions determined on the basis of the experimentaldata were very similar to those predicted by the model. Thepsychophysical functions for sucrose and the sorbitol-sucrosemixtures showed slight downward curvature. As these deviationsfrom the power law affect the predictive validity of the model,potential factors causing these curvatures are discussed.     

Temporal separation of two components of phytochrome action

Abstract In germinating seedlings of Sinapis alba nitrate reductase activity as assayed in vivo becomes accessible to phytochrome control between 15 and 17 h after sowing. Phytochrome operates via the high irradiance reaction to control nitrate reductase activity in the period 15 to 20 h after sowing. Both continuous red light and far-red light elicit this response with a strong fluence rate dependency being apparent in each case. The induction of nitrate reductase activity by light pulses at 20 h after sowing is greatly influenced by red light pre-treatments (operating through phytochrome) given between 0 and 15 h after sowing. Low fluence rate pre-treatments reduce the effectiveness of a subsequent pulse to below the level of a dark control whilst high fluence rate pre-treatments greatly increase the effectiveness of a subsequent pulse.     

Fat taste signal transduction and its possible negative modulator components

The incidence of obesity and its associated diseases including diabetes and various cardiovascular disease continues to escalate. Since the energy homeostasis executes a substantial role in fat-rich food intake and body weight regulation, it grows into a prevalent subject of interest for its strong energy density and high palatability. Over the decade, the notion that the dietary fatty acids convey signaling cues to oro-gustatory system embrace profound ability in understanding its function along with its perception of dietary fats. In this review, recent developments in the field of oleogustus and its downstream signaling mechanism in taste bud cells are analyzed. Notably, we made a brief attempt to expose the possible negative modulator components that had the potential to modulate the distinctive fat signal transduction components and its oro-gustatory mechanism. This review is in-sighted to urge the scientific community to work towards that goal to establish the libraries comprising both chemical and natural fat taste modifiers that adhere to fat taste receptors and alters its gustatory sense to proficiently combat obesity-linked complications.     

Temporal dissociation of developmental events in the chick eye under low temperature conditions

The chick embryonic eye is an excellent model for the study of vertebrate organogenesis. Key events in eye development involve thickening, invagination and cytodifferentiation of the lens primordium. While these events occur successively at different developmental stages, the extent to which these events are temporally related is largely unknown. Here we show that the lens invagination is highly sensitive to temperature. Lowering of incubation temperature to 29°C at embryonic day 2 delayed the onset of invagination of the lens, but not thickening and cytodifferentiation, leading to abnormal protrusion of the eye. The temperature shift also delayed the inward bending of the underlying retinal primordium, even in the absence of the lens. Taken together, our results suggest that lens invagination is initiated independently of thickening and cytodifferentiation, possibly by mechanisms associated with morphogenesis of the primordial retina.     

Two-component mixture cure rate model with spline estimated nonparametric components

Summary In some survival analysis of medical studies, there are often long-term survivors who can be considered as permanently cured. The goals in these studies are to estimate the noncured probability of the whole population and the hazard rate of the susceptible subpopulation. When covariates are present as often happens in practice, to understand covariate effects on the noncured probability and hazard rate is of equal importance. The existing methods are limited to parametric and semiparametric models. We propose a two-component mixture cure rate model with nonparametric forms for both the cure probability and the hazard rate function. Identifiability of the model is guaranteed by an additive assumption that allows no time-covariate interactions in the logarithm of hazard rate. Estimation is carried out by an expectation-maximization algorithm on maximizing a penalized likelihood. For inferential purpose, we apply the Louis formula to obtain point-wise confidence intervals for noncured probability and hazard rate. Asymptotic convergence rates of our function estimates are established. We then evaluate the proposed method by extensive simulations. We analyze the survival data from a melanoma study and find interesting patterns for this study.     

Sensory evaluation of character impact components in an apple model mixture

Food aromas generally are complex mixtures of volatiles. In the present study, we investigated the joint effects of hexyl acetate, trans-2-hexenal and 1-hexanol on the multi-attribute perception of an apple aroma. The first two substances were identified earlier as positive contributors to the apple aroma (high character impact), whereas the third component was identified as an irrelevant or negative contributor (low character impact). Aroma quality was quantified using a set of eight graphic rating scales. All three components had significant effects on the aroma profiles. These effects consist mainly of an effect of each component on the attribute that described its individual character and an effect of all three components on ratings on the main character attribute 'apple'. As expected, the high impact components increased 'apple' ratings, whereas the low character impact component decreased 'apple' ratings. Furthermore, intensity ratings on the attribute that corresponded with the odour of the low impact component were suppressed by the presence of high impact components. These results indicate that the contributions of odorants to the mixture's aroma are not linear combinations of separate odour intensities, because sensory interactions were observed. In addition, humans detect components in complex mixtures more accurately than studies on identification performance have suggested. We conclude that for an adequate assessment of the effects of multiple mixture components on changes in aroma perception, it is sufficient to employ multiple response scales measuring intensities of attributes that are distinctive with respect to the expected qualitative changes. Results of this approach should be subjected to multivariate methods of statistical analysis.     

Key taste components in two wild edible Boletus mushrooms using widely targeted metabolomics

Compounds from wild edible mushrooms has been reported to exert biological activities and contribute to the different flavors of mushrooms in our diet. Wild edible Boletus mushrooms are popular in Southwest China. In this study, we performed ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) based on widely targeted metabolomics analysis to identify key components. A total of 194 metabolites (113 upregulated, 81 downregulated) divided into 11 groups (49 metabolites in group lipids, 34 in amino acids and derivatives, 30 in organic acids, 18 in phenolic acids, 16 in nucleotides and derivatives, 13 in alkaloids, 6 in flavonoids, 3 in lignans and coumarins, 3 in tannins, 2 in terpenoids, and 20 in others) were found among Boletus bainiugan compared with B. subsplendidus. Through clustering analysis, principal component analysis (PCA), and orthogonal signal correction and partial least squares-discriminant analysis (OPLS-DA), different metabolites from fruiting bodies were clearly identified. Significant differences were observed in the metabolites between Boletus bainiugan and B. subsplendidus. These metabolites are involved in important biological functions. Our results provide new insights into important metabolites and theoretical basis for the taste difference of two wild edible Boletus mushrooms.