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Predicting the intent to purchase unfamiliar and familiar cheeses: the effects of attitudes, expected liking and food neophobia.

The attitude model of the theory of reasoned action (TRA) has been applied mainly to predicting the choice of familiar foods; however, the choice of unfamiliar foods may be governed by distinct factors. In the present study, 92 females rated their attitudes and subjective norms about the purchase intentions of two familiar and two unfamiliar cheeses, and the expected and actual pleasantness of them. They also completed the food neophobia scale, which measures the tendency to avoid novel foods. Neophobic persons rated the attitudes and expected and actual taste pleasantness lower than neophilics for all cheeses, except for the most familiar, mild cheese. This suggests that food neophobia also indicates the tendency not only to avoid, but also to dislike novel foods. Before tasting, attitudes and subjective norms together predicted the intent to purchase familiar cheeses better (R2=0.54 and 0.58) than for novel cheeses (R2=0.24 and 0.35); thus, the basic TRA model was not as useful in predicting intent to purchase unfamiliar as familiar cheeses. The predictions especially for the novel cheeses were clearly improved by including expected pleasantness ratings in the model. The usefulness of the food neophobia score as an additional predictor was not clearly supported. Attitudes and subjective norms measured before tasting were poor predictors of purchase intents after tasting, which implies the importance of taste and direct product experience in food choice.

Adult↗

Intracellular Ca2+ and the phospholipid PIP2 regulate the taste transduction ion channel TRPM5.

The transduction of taste is a fundamental process that allows animals to discriminate nutritious from noxious substances. Three taste modalities, bitter, sweet, and amino acid, are mediated by G protein-coupled receptors that signal through a common transduction cascade: activation of phospholipase C beta2, leading to a breakdown of phosphatidylinositol-4,5-bisphosphate (PIP2) into diacylglycerol and inositol 1,4,5-trisphosphate, which causes release of Ca2+ from intracellular stores. The ion channel, TRPM5, is an essential component of this cascade; however, the mechanism by which it is activated is not known. Here we show that heterologously expressed TRPM5 forms a cation channel that is directly activated by micromolar concentrations of intracellular Ca2+ (K1/2 = 21 microM). Sustained exposure to Ca2+ desensitizes TRPM5 channels, but PIP2 reverses desensitization, partially restoring channel activity. Whole-cell TRPM5 currents can be activated by intracellular Ca2+ and show strong outward rectification because of voltage-sensitive gating of the channels. TRPM5 channels are nonselective among monovalent cations and not detectably permeable to divalent cations. We propose that the regulation of TRPM5 by Ca2+ mediates sensory activation in the taste system.

Animals↗

Sweet and fat taste preference in obesity have different associations with personality and eating behavior.

The aim of this study was to test associations between self-reported attitudes of sweet and fat taste preferences and psychological constructs of eating behavior and personality in obesity. Sixty obese patients were included. The Three Factor Eating Questionnaire was used for the assessment of psychological constructs of eating behavior, and the Swedish universities Scales of Personality was used for measuring personality traits. A strong sweet taste preference was associated with more neurotic personality traits (P=.003), in particular lack of assertiveness (P=.001) and embitterment (P=.002). Strong fat taste preference was rather related to lower levels of the eating characteristic cognitive restraint (P=.017), implying less attempts to restrict and control food intake. Whereas strong sweet taste preference was linked to a personality style in obesity, strong fat preference could be more an aspect of eating behavior. A psychobiological stress model is discussed in relation to the results on sweet preference and hampered personality functioning.

Adult↗

The pig as a model for the study of obesity and of control of food intake: a review.

The use of the pig for studies of food intake and obesity is reviewed. Effects of ambient temperature and taste on food intake as well as satiety factors impicating both neural and hormonal mechanisms originating in the gastrointestinal tract are considered; the integration of information in the central nervous system for both internal and external sources is hypothesized. Special concerns of food intake controls in the neonate are discussed, including effects of neonate sweet preference on food intake, gastrointestinal satiety factors, and hypoglycemia as a stimulus for food ingestion.For obesity studies, pigs offer several advantages, including their general physiological similarity to humans, similar fat cell size, and body fat distribution. Lipogenesis, lipolysis, and lipid mobilization are under intensive study in swine and the information obtained may have important application in studies of human obesity. The voluminous literature on metabolic differences between genetically lean versus obese populations of pigs suggests possibilities for application in humans. Greater characterization of differences and similarities between pigs and humans in important metabolic parameters related to regulation of food intake and obesity should facilitate better understanding and control of human obesity.

Adipose Tissue↗

Flavor preferences, food intake, and weight gain in baboons (Papio sp.).

To evaluate the influence of flavor on ad lib consumption and on associated changes in body weight, female baboons, 7-15 years of age, served in two experiments with seven monkey chows which were identical except for flavor: lemon, orange, apple, sugar, fruit punch, chocolate, and unflavored. In the first experiment, two groups of animals (n=7 and 4) received five of the seven flavors, presented in daily pair-wise combinations. Analysis of quantities consumed demonstrated marked and consistent flavor preferences in individual baboons. Although specific preference varied between animals, total amounts consumed of the various flavors differed significantly, with rank ordering clearly evident. Overall food intake and body weights increased significantly over baseline values obtained with a standard, unflavored chow. In the second experiment, three baboons received chow of a preferred flavor for nine weeks. Amounts consumed and body weights increased significantly over baseline. These results indicate that flavored chows may be useful for producing a nonhuman primate behavioral model of obesity and for inducing animals to eat otherwise unpalatable diets.

Animals↗

Spike train metrics.

Quantifying similarity and dissimilarity of spike trains is an important requisite for understanding neural codes. Spike metrics constitute a class of approaches to this problem. In contrast to most signal-processing methods, spike metrics operate on time series of all-or-none events, and are, thus, particularly appropriate for extracellularly recorded neural signals. The spike metric approach can be extended to multineuronal recordings, mitigating the 'curse of dimensionality' typically associated with analyses of multivariate data. Spike metrics have been usefully applied to the analysis of neural coding in a variety of systems, including vision, audition, olfaction, taste and electric sense.

Action Potentials↗

Crossmodal integration--insights from the chemical senses.

Our understanding of the neural correlates of crossmodal binding in the human brain derives almost exclusively from studies of audition, vision and somatosensation. A new study by Gottfried and Dolan extends our understanding of multisensory integration by showing that facilitation of odor detection by visual cues depends on object congruency, as well as on enhanced activity in the superior temporal sulcus and a region of the orbitofrontal cortex that is adjacent to olfactory association cortex.

Brain Mapping↗

Tomato aromatic amino acid decarboxylases participate in synthesis of the flavor volatiles 2-phenylethanol and 2-phenylacetaldehyde.

An important phenylalanine-derived volatile compound produced by plants is 2-phenylethanol. It is a major contributor to flavor in many foods, including fresh fruits, such as tomato, and an insect-attracting scent in roses and many other flowers. Despite the centrality of 2-phenylethanol to flavor and fragrance, the plant genes responsible for its synthesis have not been identified. Here, we describe a biosynthetic pathway for 2-phenylethanol and other phenylalanine-derived volatiles in tomato fruits and a small family of decarboxylases (LeAADC1A, LeAADC1B, and LeAADC2) that can mediate that pathway's first step. These enzymes each catalyze conversion of phenylalanine to phenethylamine and tyrosine to tyramine. Although tyrosine is the preferred substrate in vitro, phenylalanine levels in tomato fruits far exceed those of tyrosine, indicating that phenylalanine is a physiological substrate. Consistent with this view, overexpression of either LeAADC1A or LeAADC2 in transgenic tomato plants resulted in fruits with up to 10-fold increased emissions of the products of the pathway, including 2-phenylacetaldehyde, 2-phenylethanol, and 1-nitro-2-phenylethane. Further, antisense reduction of LeAADC2 significantly reduced emissions of these volatiles. Besides establishing a biosynthetic route, these results show that it is possible to change phenylalanine-based flavor and aroma volatiles in plants by manipulating expression of a single gene.

Acetaldehyde↗

Ginger-chemistry, technology, and quality evaluation: part 2.

Ginger is used in more ways than any other spice. This monograph, published in two parts, comprehensively reviews production, trade, processing, chemistry, and evaluation of quality. Botany, world varieties, agronomy, crop improvement, and potential are reviewed briefly with emphasis on the yield of functional components. Processing for the market, international trade patterns and factors influencing them are discussed. Derived products such as ginger powder, syruped ginger, volatile oil, and oleoresin are discussed in greater detail. The increasing world demand for quality products of added value such as the oleoresin and volatile oil show the prospects for their production in the growing countries. The chemistry of the components which contribute aroma and pungency that characterize ginger is critically reviewed. The second part deals with evaluation of quality. The physicochemical parameters prescribed as a measure of quality for ginger and its products in the existing standards, can assure only hygienic quality and purity, and possibly the source, when new parameters such as GC-finger prints are included. The importance of sensorily evaluating flavor quality is emphasized to understand the variation in flavor quality required by the industrial and retail markets. Related areas, such as problems in sensory evaluation of intense flavored substances, objective flavor profile analysis, correlation of instrumental and sensory data are discussed, and our recent work in this area is summarized. Areas where more research is needed are indicated. Other areas briefly discussed are functional, physiological, and toxicological properties in use of ginger; biosynthetic aspects of components stimulating flavor; structure and pungency and chemistry of spices from allied species and genera. A comprehensive bibliography is provided to aid in further study and research.

Chemical Phenomena↗

SW.B6-Soa(b) nontaster congenic strains completed and a sucrose octaacetate congenic quartet tested with other bitters.

Ten SW.B6 SOA nontaster strains congenic with the SWR/J SOA taster inbred strain were bred via repeated backcross-intercross cycles, with selection for nontasting in each cycle. Preference ratio distributions and phenotypic proportions across cycles at 0.1 mM SOA were consistent with monogenic predictions. The SW.B6 mice completed a congenic quartet with the SWR/J, B6.SW SOA taster and C57BL/6J SOA nontaster strains. The Soa locus controlled avoidance differences within the quartet for SOA, raffinose undecaacetate, glucose pentaacetate and brucine. Background genes not linked to Soa controlled avoidance differences for L-phenylalanine and ethanol. Avoidance of bitter picric acid was influenced by the Soa locus, but avoidance of acetic acid was not. The quartet pattern for quinine HCl was unclear, with indications of both Soa and background effects. Two forms of ribose tetraacetate yielded different patterns. Avoidance differences controlled by the Soa locus were found for the pyranose form; however, all four strains avoided the furanose form. The pleiotropic effects of Soa allele substitution within the quartet were limited to a subset of bitter compounds.

Acids↗

Estimation of Radiation Exposures of "Liquidators" of the Chernobyl Nuclear Power Station; Identification of Risk Groups.

Identification of workers who are at high risk and at low risk as a result of participation in the cleanup of the consequences of the accident at the Chernobyl nuclear power station ("liquidators") is important both for scientific research and for the medical care of the individuals involved. Using register data for 36,700 liquidators, the authors estimated the relationships between radiation doses and the following factors: time of arrival at the accident zone, irradiation conditions, and possible health effects following the exposures. The analyses took into account types of work (decontamination, cordon work, building); places and circumstances of work (inside or outside or with machinery); and the use of individual protection measures. Included in possible effects on health were changes in hematologic indexes, weakness, headache, dryness or tickling of the throat, cough, facial hyperemia, metallic taste, anorexia, nausea, vomiting, heaviness in the epigastric region, and instability of defecation. With the help of mathematical models, the rating for each factor was assessed, and on this basis the liquidators were subdivided into risk groups. For workers for whom dose information was not available, probable doses could be calculated. The three most influential variables were time of starting work, type of work done, and the number of health effects.

Journal Article↗

Molecular basis of bitter taste: the T2R family of G protein-coupled receptors.

The sense of taste responds to a large variety of stimuli through specific transduction mechanisms. The molecular events in the perception of bitter taste are believed to start with the binding of specific water-soluble molecules to G-protein-coupled receptors encoded by the type 2 family of taste receptor genes and expressed at the surface of taste receptor cells. Recent advances in the identification and cloning of the complete repertoire of genes of this family in humans and rodents provide an opportunity to address unresolved questions in bitter taste. The functional characterization of some of the receptors that these genes encode suggests that it will be possible to understand more precisely their specific functions.

Animals↗