A psychophysical model for gustatory quality.
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Adolescent↗
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Correlations between growth parameters of spoilage micro-organisms and shelf-life of pork stored under air and modified atmosphere at -2, 4 and 10 degrees C.
The correlations of the growth parameters (the initial cell number (N(0)), maximum cell number (N(max)), maximum specific growth rate (mu(max)), lag-phase (lambda)) of typical spoilage micro-organisms (lactic acid bacteria (LAB), coliforms, pseudomonads, Brochothrix thermosphacta) growing on sliced pork to the sensory shelf-life and microbial shelf-life were investigated. The changes in sensory quality and proliferation of micro-organisms on pork shoulder were studied at different atmosphere conditions (air and 40%CO(2)/59%N(2)/1%O(2)) and temperatures (-2, 4 and 10 degrees C). Microbial counts were fitted to the modified-Gompertz equation to obtain the growth parameters of different micro-organisms. B. thermosphacta and coliforms were predominant bacteria associated with spoilage of pork under all temperatures and air conditions. However, pseudomonads could only dominate under regular atmosphere condition. Using multiple linear regression, high correlations were found between the lag-time (lambda) of LAB (0.9814, 0.9830), B. thermosphacta (0.9895, 0.9849), or the maximum specific growth rate (mu(max)) of coliforms (-0.9583, -0.9695) and the microbial shelf-life and sensory shelf-life, respectively. The mu(max) and lambda of micro-organisms correlated well with microbial and sensory shelf-life. The shelf-life of pork is mainly correlated with the growth parameters of mu(max) and lambda than by N(max).
Animals↗
Food for thought: hedonic experience beyond homeostasis in the human brain.
Food intake is an essential human activity regulated by homeostatic and hedonic systems in the brain which has mostly been ignored by the cognitive neurosciences. Yet, the study of food intake integrates fundamental cognitive and emotional processes in the human brain, and can in particular provide evidence on the neural correlates of the hedonic experience central to guiding behaviour. Neuroimaging experiments provide a novel basis for the further exploration of the brain systems involved in the conscious experience of pleasure and reward, and thus provide a unique method for studying the hedonic quality of human experience. Recent neuroimaging experiments have identified some of the regions involved in the cortical networks mediating hedonic experience in the human brain, with the evidence suggesting that the orbitofrontal cortex is the perhaps strongest candidate for linking food and other kinds of reward to hedonic experience. Based on the reviewed literature, a model is proposed to account for the roles of the different parts of the orbitofrontal cortex in this hedonic network.
Animals↗
Model for voluntary wine and alcohol consumption in rats.
It has been suggested that moderate consumption of ethanol and wine has a protective effect on human health. Animal models used to date for alcohol consumption can not mimic real situations in humans because the consumption is forced and/or excessive. The present study proposes to determine the effects of a voluntary and ad lib consumption model more similar to that of human behavior. Male Wistar rats had free access to either standard diet and water or the same diet plus red wine, sweet wine, or a solution equivalent to red wine (13.5% ethanol) or to sweet wine (20% ethanol + 130 g/L sucrose) for 30 days or 6 months. Daily wine consumption was 15.8 +/- 0.9 and 2.0 +/- 0.2 ml/day for sweet and red wines, respectively. The consumption of each of the alcoholic solutions was similar to that of the wine they were simulating. Drinking wine or ethanol did not affect food and water intakes or growth rate. Plasma metabolites were not substantially affected by consumption of wine or ethanol. Although moderate and high wine consumption did not change the activity of plasma marker enzymes of tissue damage, the consumption of the 2 alcoholic solutions caused a long-term increase in the activity of aspartate aminotransferase. It seems that wine consumption protects the organism from hepatic lesions induced by ethanol alone.
Alcohol Drinking↗
Application of shelf life decision system (SLDS) to marine cultured fish quality.
Growth of natural microflora of marine cultured, air-packed, sea bass (Dichentrachus labrax) was studied at isothermal conditions in the 0-15 degrees C range and kinetically modelled using the four-parameter Logistic equation. Sensory shelf life was correlated to pseudomonad population and sensory acceptability was correlated to a pseudomonad level, Ns, of 10(7). The variability of their initial population was quantitatively shown and a conductance-based rapid method specific to sea bass pseudomonad enumeration was established as a practical means of N0 determination, required in shelf life predictions. Kinetic models, shelf life correlations and N0 data were incorporated into the shelf life decision system (SLDS) shown to be an effective tool for marine cultured sea bass chill chain management leading to optimization of quality of the fish at consumer's end.
Animals↗
Modeling dynamic flavor release from water.
A mathematical model derived from the convective mass transfer theory was developed to predict dynamic flavor release from water. A specific mass transfer correlation including a new term for volatile permeability was applied. The model was entirely based on physicochemical constants of flavor compounds and on some parameters of an apparatus used for validation. The model predicted a linear pattern of release kinetics during the first 30 s and large differences of absolute release for individual compounds. Both calculated and experimentally determined release profiles of a test mixture of flavors showed good agreement.
Kinetics↗
Prediction of aged red wine aroma properties from aroma chemical composition. Partial least squares regression models.
Partial least squares regression (PLSR) models able to predict some of the wine aroma nuances from its chemical composition have been developed. The aromatic sensory characteristics of 57 Spanish aged red wines were determined by 51 experts from the wine industry. The individual descriptions given by the experts were recorded, and the frequency with which a sensory term was used to define a given wine was taken as a measurement of its intensity. The aromatic chemical composition of the wines was determined by already published gas chromatography (GC)-flame ionization detector and GC-mass spectrometry methods. In the whole, 69 odorants were analyzed. Both matrixes, the sensory and chemical data, were simplified by grouping and rearranging correlated sensory terms or chemical compounds and by the exclusion of secondary aroma terms or of weak aroma chemicals. Finally, models were developed for 18 sensory terms and 27 chemicals or groups of chemicals. Satisfactory models, explaining more than 45% of the original variance, could be found for nine of the most important sensory terms (wood-vanillin-cinnamon, animal-leather-phenolic, toasted-coffee, old wood-reduction, vegetal-pepper, raisin-flowery, sweet-candy-cacao, fruity, and berry fruit). For this set of terms, the correlation coefficients between the measured and predicted Y (determined by cross-validation) ranged from 0.62 to 0.81. Models confirmed the existence of complex multivariate relationships between chemicals and odors. In general, pleasant descriptors were positively correlated to chemicals with pleasant aroma, such as vanillin, beta damascenone, or (E)-beta-methyl-gamma-octalactone, and negatively correlated to compounds showing less favorable odor properties, such as 4-ethyl and vinyl phenols, 3-(methylthio)-1-propanol, or phenylacetaldehyde.
Chromatography, Gas↗
Detailed investigation of the production of the bread flavor component 6-acetyl-1,2,3,4-tetrahydropyridine in proline/1,3-dihydroxyacetone model systems.
The production of 6-acetyl-1,2,3,4-tetrahydropyridine (ATHP), an important Maillard flavor component, in the reaction of L-(-)-proline and 1,3-dihydroxyacetone was investigated as a function of different reaction conditions. The two major side products from the reaction were identified as 5-acetyl-6-methyl-2,3-dihydro-1H-pyrrolizine and 5-acetyl-6-hydroxymethyl-2,3-dihydro-1H-pyrrolizine, the last one being a new compound described here for the first time. A maximum yield of ATHP of 2.7 mol % from L-(-)-proline and 1,3-dihydroxyacetone was noted at 130 degrees C in the presence of 2 equiv of sodium bisulfite. The role of sodium bisulfite as a reducing species, and as a stabilizing agent for 6-acetyl-1,2,3,4-tetrahydropyridine, was clarified. In view of the new data obtained, the hypothesized mechanism of formation of 6-acetyl-1,2,3,4-tetrahydropyridine was confirmed, and the reaction mechanisms leading to 2,3-dihydro-1H-pyrrolizines were reconsidered.
Bread↗
Selective breeding for high and low alcohol preference in mice.
High and low alcohol preference (HAP and LAP, respectively) mice were created by 10 generations of bidirectional selection for differences in two-bottle choice alcohol consumption. The progenitors used for selection were HS/lbg mice, which are a genetically defined, outbred stock. During selection, mice had 24-h, daily access to 10% alcohol (v/v) and water ad libitum for 30 days and were selected based on the alcohol (g/kg) consumed per day over the entire period. Food was available ad libitum. At S10, line means for alcohol consumption differed greatly, with consumption of over 12 g/kg per day in the HAP mice and less than 2 g/kg per day in the LAP mice. Realized heritability for bidirectional selection was approximately 0.2. Female mice consumed more alcohol than male mice. There were no differences between lines in alcohol elimination rate, nor were there line differences in intake of salt or quinine solutions. However, consumption of saccharin solutions was greater in HAP mice than LAP mice, consistent with previous findings of a genetic correlation between sweet preference and alcohol drinking. Because the mouse genome is relatively well characterized, these selected lines should prove a useful tool for assessment of the genetic basis of, and phenotypes that correlate with, alcohol drinking.
Alcohol Drinking↗
Bitterness and chemical structure.
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Chemical Phenomena↗
Influence of a selective histamine H3 receptor antagonist on hypothalamic neural activity, food intake and body weight.
OBJECTIVE: This study was conducted to elucidate whether antagonistic targeting of the histamine H3 receptor increases hypothalamic histamine levels, in parallel with decreases in food intake and body weight. METHODS: The competitive antagonist potency of a recently synthesized histamine H3 receptor antagonist, NNC 38-1049, was studied in intact HEK293 cells expressing human or rat histamine H3 receptor, in which NNC 38-1049 was allowed to antagonize the effect of the H3 receptor agonist R-alpha-methylhistamine on isoprenaline-induced accumulation of cAMP. The affinity of NNC 38-1049 for a number of variants of the histamine receptor was also determined. Following single dosing of normal rats with NNC 38-1049, hypothalamic histamine levels were assessed by means of microdialysis. Plasma and brain levels of NNC 38-1049 and acute effects on food intake and energy expenditure were followed after oral doses of 3-60 mg/kg. Potential side effects were examined with rat models of behaviour satiety sequence (BSS), pica behaviour and conditioned taste aversion (CTA). Intakes of food and water together with body weight were recorded for 15 days during daily dosing of dietary obese rats. RESULTS: NNC 38-1049 was found to be a highly specific and competitive antagonist towards both human and rat histamine H3 receptors, and measurable amounts of NNC 38-1049 were found in the plasma of rats following single oral doses of 3-60 mg/kg and in the brain after 15-60 mg/kg. Following single intraperitoneal injections of NNC 38-1049 (20 mg/kg), significant increases in extracellular histamine concentrations were observed. The same dose did not change BSS or pica behaviour acutely, nor did it induce CTA following repeated administration for 7 days. Reductions in food intake were seen very soon after administration, and occurred in a dose-dependent fashion. Energy expenditure was unchanged, but the respiratory quotient (RQ) tended to decrease at higher doses, indicating an increase in lipid oxidation. Twice daily administration of 20 mg/kg of NNC 38-1049 in old and dietary obese rats resulted in sustained reduction of food intake throughout a 2-week study, and was associated with a highly significant (P<0.01) decrease in body weight compared with controls (-18.4+/-3.4 vs +0.4+/-2.7 g). The same dose of NNC 38-1049 produced an acute decrease of water intake, but 24 h intakes were not significantly changed. CONCLUSIONS: The results of this study strongly support the idea that an increase in the hypothalamic concentration of histamine produces a specific reduction of food intake and that this effect can be translated into a decrease in body weight.
Administration, Oral↗
Identification and expression of a novel gene in odour-taste associative learning in the terrestrial slug.
Odour-taste associative learning in the terrestrial slug offers a useful model for long-term memory formation and retention. The genes which are expressed over 2 h after a learning event are thought to include those related to memory formation and/or consolidation. It is very important to examine what kinds of genes are expressed following associative learning. We identified a novel slug gene, the expression of which was regulated by associative learning and mostly restricted to the procerebrum (PC), a place that olfactory information is believed to be processed in slug. This gene encodes a 121 amino acid, 18 kDa secretory protein which we term LAPS18. Expression of the LAPS18 gene was induced in somata and the protein spread to neurites in the PC of slugs subjected to paired conditioning. Recombinant LAPS18 promoted the aggregation and movement of PC neurones in culture and they were blocked by the anti-LAPS18 antibody. Beads coupled with LAPS18 protein attached to PC neurones and the beads aggregated through PC cells but not by themselves, suggesting that LAPS18 may require a counterpart molecule for PC neurone aggregation. An increased expression and translocation of LAPS18 protein after paired conditioning may be needed for long-term memory formation and retention in the slug. Since genes homologous to LAPS18 genes in the land slug Limax are found from vertebrates including human, analysing the expression and function of LAPS18 may be important in understanding the molecular mechanism of memory formation and retention.
Amino Acid Sequence↗
Volatile flavor release from foods during eating.
Classical analyses for volatile flavors (headspace or distillation/extract methods) give information on either the volatiles present in the air above a food before eating or the total volatile composition of the food. When foods are eaten, however, many changes take place (such as hydration/dilution with saliva, increase in surface area, etc.) that affect the release of volatiles from the food and therefore the profile of volatiles that are sensed in the nose. If we wish to study the relationship between flavor volatiles and the sensory properties of a food, it seems logical to measure the volatile profile that exists during eating. Although volatile flavor release during eating has been measured using a variety of sensory and psychophysiological analyses, only recently have instrumental methods been developed to measure the release of volatile compounds in humans as they eat. Whereas the sensory data give an overall measure of flavor perception, instrumental analyses can potentially follow the release of each and every flavor volatile and thus give a full picture of the aroma profiles generated during eating. From these instrumental measurements, a number of key factors have been identified. First, it has been shown that the volatile profile measured during eating is indeed different from the headspace profile of whole foods. Second, it is clear that the volatile profile in-mouth changes with time as the state of the food changes with chewing. Third, the volatile release from low-water foods is affected by the rate and extent of hydration in-mouth. The ability to measure aroma before, during, and after eating may lead to an understanding of the links between aroma release, interaction of volatiles with aroma sensors in the nose, and the overall perception of food flavor.
Eating↗
Psychophysical models for mixtures of tastants and mixtures of odorants.
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Animals↗
Neural events and the psychophysical law.
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Auditory Perception↗
Flavor release of diacetyl and 2-heptanone from cream style dressings in three mouth model systems.
The release of volatile compounds from a cream style dressing, which consisted of a thickening agent dispersed in the water phase of an oil in water (o/w) type of emulsion, was studied by the purge-and-trap (PT), dynamic head space mastication (DHM) and dynamic headspace (DH) model systems for diacetyl and 2-heptanone as two volatile compounds. Big differences were detected in the quantity of volatiles released by the three models for both diacetyl and 2-heptanone: PT released the most, followed by DHM and DH. Nitrogen gas bubbling in PT and plunger up-and-down motion in DHM mimic mouth movements and promoted volatile release more than DH. The quantity of volatiles released depended on the nitrogen gas flow rate and isolation period with both the PT and the DHM model. Static headspace measurements indicated that no interaction occurred between the volatiles and the dispersion thickening agent, nor between the volatiles and protein of saliva.
Diacetyl↗
Sensory shelf life of dulce de leche.
The objectives of this research were to determine the sensory cutoff points for dulce de leche (DL) critical descriptors, both for defective off-flavors and for storage changes in desirable attributes, and to estimate the shelf life of DL as a function of storage temperature. The critical descriptors used to determine the cutoff points were plastic flavor, burnt flavor, dark color, and spreadability. Linear correlations between sensory acceptability and trained panel scores were used to determine the sensory failure cutoff point for each descriptor. To estimate shelf life, DL samples were stored at 25, 37, and 45 degrees C. Plastic flavor was the first descriptor to reach its cutoff point at 25 degrees C and was used for shelf-life calculations. Plastic flavor vs. storage time followed zero-order reaction rate. Shelf-life estimations at different temperatures were 109 d at 25 degrees C, 53 d at 37 degrees C, and 9 d at 45 degrees C. The activation energy, necessary to calculate shelf lives at different temperatures, was 14,370 +/- 2080 cal/mol.
Color↗
Conditioning of the immune response.
Experimental studies in humans and experimental animals document the acquisition and extinction of classically conditioned alterations of different parameters of humoral- and cell-mediated immune responses. Although the aversive effects of cyclophosphamide in a taste aversion learning paradigm has been the most frequently used model, conditioned immunomodulatory effects are not confined to this conditioning procedure, and they are not limited to cyclophosphamide or, for that matter, the use of immunomodulating drugs as unconditioned stimuli. Conditioned changes in immunologic reactivity have also been found to modulate the progression of spontaneously-developing or experimentally-induced pathophysiological processes in experimental animals. The available data on the immunoregulatory effects of conditioning indicate that the immune system, like other systems operating in the interests of homeostasis, is integrated with other physiological processes and is therefore influenced by and capable of influencing the brain.
Animals↗