Temporal dissociation of taste mixture components

Reaction times to salty and bitter tastes as single stimuliand in mixture were measured using response time deadlines rangingfrom 300 to 2500 ms. Salty reaction times were the same whethersalty was in mixture with bitter or a single stimulus, and theywere always shorter than bitter reaction times. Reaction timeto bitter was slower in mixture with salty than as a singletaste. Salty, alone and in mixture, was correctly identifiedon {small tilde}80% of the trials within 500 ms while correctbitter identifications did not reach similar levels until 1000ms. Bitter in mixture with salty never reached that level ofcorrect responding and correct responses actually decreasedslightly at response time deadlines of 2500 ms. The resultsshow that differences in taste onset latency are great enoughto allow identification of single tastes in mixtures.     

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.     

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.     

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.     

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.     

Space, time and statistics

Spatiotemporal Models of Population and Community Dynamics by T. Czárán Chapman and Hall, Population and Community Biology Series, 1997. ￡59.00 hbk (xvii +284 pages) ISBN 0 412 57550 7.     

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.     

Space and time in visual context

No sensory stimulus is an island unto itself; rather, it can only properly be interpreted in light of the stimuli that surround it in space and time. This can result in entertaining illusions and puzzling results in psychological and neurophysiological experiments. We concentrate on perhaps the best studied test case, namely orientation or tilt, which gives rise to the notorious tilt illusion and the adaptation tilt after-effect. We review the empirical literature and discuss the computational and statistical ideas that are battling to explain these conundrums, and thereby gain favour as more general accounts of cortical processing.     

Reaction time in the perceptual processing of taste quality

A series of experiments examined possible strategies human subjectsmight use in tasks requiring rapid detection or recognitionof a taste quality. In a reaction time (RT) paradigm, subjectswere to decide whether each of a series of stimuli flowed overthe tongue contained a previously designated target taste. Severaltasks of varying difficulty were used. The simplest task requiredsubjects to decide whether the target taste or water was presented.The most difficult task required discrimination between twodifferent target tastes in a series of mixtures formed by orthogonallycombining the target taste with two different irrelevant tastes.The speed at which subjects could detect and/or recognize targettastes was related to the RT for the particular taste. However,it was also clear that other variables, including the specificstimuli in the mixtures and the cognitive demands placed onthe subjects, influenced performance. These results suggestthat differences in taste onset time, as indexed by RT, canserve as a cue which subjects use to aid identification of singletastes in a mixture. It is concluded that the ease with whichsubjects can identify single tastes in a mixture is relatedto, among other variables, the differences in taste onset timebetween the tastes.     

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.