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Results for “Taste modeling”

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At least 721 records · Page 40Linked to original sources
PubMed2003

Antibacterial activity of 11 essential oils against Bacillus cereus in tyndallized carrot broth.

The antibacterial activity of 11 essential oils from aromatic plants against the strain INRA L2104 of the foodborne pathogen Bacillus cereus grown in carrot broth at 16 degrees C was studied. The quantity needed by the essential oils of nutmeg, mint, clove, oregano, cinnamon, sassafras, sage, thyme or rosemary to produce 14-1110% relative extension of the lag phase was determined. Total growth inhibition of bacterial spores was observed for some of the antimicrobial agents assayed. The addition of 5 microl cinnamon essential oil per 100 ml of broth in combination with refrigeration temperatures of <or=8 degrees C produced the conditions necessary to inhibit the growth of B. cereus for at least 60 days in a model, refrigerated minimally processed food product, made with carrots and tyndallized. This is especially important considering that the psychrotrophic enterotoxigenic strain of B. cereus INRA TZ415 was able to grow in this substrate at low temperatures in the absence of any essential oil. Furthermore, the study of the sensory characteristics of the final product suggests that the use of cinnamon essential oil can be considered as an alternative to "traditional food preservatives".

Bacillus cereus↗
PubMed2001

Antisweet saponins from Gymnema sylvestre.

Three new oleanane-type triterpene glycosides (1-3), along with the sodium salt of alternoside II (4), were isolated from an ethanol extract of the leaves of Gymnema sylvestre. The structures of these new saponins were identified as 21 beta-O-benzoylsitakisogenin 3-O-beta-D-glucopyranosyl(1-->3)-beta-D-glucuronopyranoside (1), the potassium salt of longispinogenin 3-O-beta-D-glucopyranosyl(1-->3)-beta-D-glucuronopyranoside (2), and the potassium salt of 29-hydroxylongispinogenin 3-O-beta-D-glucopyranosyl(1-->3)-beta-D-glucuronopyranoside (3). The aglycon of 3, gymnemagenol (3a), was characterized as 3 beta,16 beta,28, 29-tetrahydroxyolean-12-ene. Structure elucidation was accomplished by interpretation of NMR (DQF-COSY, HMQC, and HMBC) results, FABMS, and hydrolysis. Saponin 1 and the sodium salt of alternoside II (4) exhibited antisweet activity.

Adult↗
PubMed1999

The pH response of rat cutaneous nociceptors correlates with extracellular [Na+] and is increased under amiloride.

Excess hydrogen ions induce sustained nociceptor excitation as well as pain, and this has been suggested, with evidence from sensory ganglion cells, to result from gating a slowly inactivating sodium/calcium inward current. In the rat skin-nerve preparation, isolated receptive fields of pH-sensitive C-fibre terminals were exposed to low-pH solutions of various sodium concentrations. The pH responses showed a good correlation with log [Na+]e, which supports the above model. Amiloride has previously been shown to block a pH-induced Na+ current involved in sensory transduction in hamster taste cells; however, it has been shown to act differently in cutaneous nociceptors. Amiloride induced a dose-dependent increase in and prolongation of the nociceptive pH responses, with a prominent acceleration of the onset. The latter could be mimicked by replacing external sodium with sucrose, thus impeding sodium-proton antiport. Together, the findings indicate functional expression of amiloride-sensitive Na+/H+-antiporters, which enable the nociceptive nerve endings to extrude invading H+. Intracellular acidification may thus compete with Na+/H+ exchange, and pHi may be decisive in the transduction of nociception and pain from tissue acidosis.

Amiloride↗
PubMed2004

Synaptic and spiking dynamics underlying reward reversal in the orbitofrontal cortex.

Cognitive and emotional flexibility involve a coordinated interaction between working memory, attention, reward expectations, and the evaluation of rewards and punishers so that behaviour can be changed if necessary. We describe a model at the integrate-and-fire neuronal level of the synaptic and spiking mechanisms which can hold an expectation of a reward rule in working memory, and can reverse the reward rule if expected rewards are not obtained. An example of a reward rule is that stimulus 1 is currently associated with reward, and stimulus 2 with punishment. The attractor-based reward rule working memory incorporates a spike-frequency synaptic adaptation mechanism which supports the neural switching between rules by being shut down by a general inhibitory input produced by punishment, so that when the attractor starts up again is in the opposite state. The mechanism can implement one-trial reward reversal, which is a property of orbitofrontal cortex neurons. We show how this reward rule input can operate in a biased competition way to influence which one of two stimuli is currently associated with reward and which with punishment, and to map the stimuli correctly to the reward or punishment representations, providing a basis for action selection required to obtain the reinforcer.

Action Potentials↗
PubMed2004

In vitro study of the influence of physiological parameters on dynamic in-mouth flavour release from liquids.

Influences of shear rate (surface extension), airflow, in-mouth headspace volume, synthetic saliva and human epithelial cells (modelling mucosa) on the initial dynamic flavour release from liquids were analysed. Simulating physiological mouth parameters, initial dynamic flavour release experiments over a time period of 30 s were carried out using a proven mouth model apparatus. Flavour compounds of different chemical classes were dissolved in water or in aqueous starch hydrolysate in concentrations typically present in food ( micro g/l to mg/l). Forced by increasing shear rates the enlargement of the gas-liquid interface (vortex formation) caused an increased release of flavour molecules. The release of less soluble compounds was reduced by increasing shear forces due to an improved dissolution. Increasing volumetric airflow rates resulted generally in higher release rates and in a change of pattern of release kinetics. Maximum flavour release was found at a ratio of 1:1 for in-mouth headspace and liquid volume. Neither addition of saliva alone nor the combination of saliva and mucosa showed significant influence on in-mouth flavour release from liquids in the model mouth.

Chromatography, Gas↗
PubMed2006

Heritability and genetic covariation of sensitivity to PROP, SOA, quinine HCl, and caffeine.

The perceived bitterness intensity for bitter solutions of propylthiouracil (PROP), sucrose octa-acetate (SOA), quinine HCl and caffeine were examined in a genetically informative sample of 392 females and 313 males (mean age of 17.8 +/- 3.1 years), including 62 monozygotic and 131 dizygotic twin pairs and 237 sib pairs. Broad-sense heritabilities were estimated at 0.72, 0.28, 0.34, and 0.30 for PROP, SOA, quinine, and caffeine, respectively, for perceived intensity measures. Modeling showed 1) a group factor which explained a large amount of the genetic variation in SOA, quinine, and caffeine (22-28% phenotypic variation), 2) a factor responsible for all the genetic variation in PROP (72% phenotypic variation), which only accounted for 1% and 2% of the phenotypic variation in SOA and caffeine, respectively, and 3) a modest specific genetic factor for quinine (12% phenotypic variation). Unique environmental influences for all four compounds were due to a single factor responsible for 7-22% of phenotypic variation. The results suggest that the perception of PROP and the perception of SOA, quinine, and caffeine are influenced by two distinct sets of genes.

Adolescent↗
PubMed1997

Stages of dietary change among nationally-representative samples of adults in the European Union.

OBJECTIVE: To investigate the distribution across the different stages of change for each of the 15 participating European countries, and the effect of socio-demographic variables such as sex and education on this distribution. Also to assess the relationships between stages of change and influences of food choice, and other variables. DESIGN: A cross-sectional study in which quota-controlled, nationally-representative samples of approximately 1000 adults from each country completed a face-to-face interview-assisted questionnaire. SETTING: The survey was conducted between October 1995 and February 1996 in the 15 member states of the European Union. SUBJECTS: 14331 subjects (aged 15 y upwards) completed the questionnaire. Data were weighted by population size for each country and by sex, age and regional distribution within each member state. Subjects were divided into five different categories according to their attitudes towards 'changing their eating habits in order to eat healthier': (1) Precontemplation; do not consider any changes, (2) Contemplation; consider changes, (3) Decision; make plans to change, (4) Action; carry out the changes, and (5) Maintenance; maintained changes for more than six months. RESULTS: 52% of the subjects were in the precontemplation stage, whereas 31% of the subjects were in the maintenance stage. Two, one, and seven percent of subjects were in the contemplation, decision and action stage, respectively. In the Mediterranean countries, and in Germany, there were more people (55-64%) in the precontemplation stage, whereas in the Scandinavian countries there were less people in precontemplation stage (20-38%). The opposite was true for the maintenance stage, whereas women and people with a higher education level tended to be more in the maintenance stage. With respect to influence on food choice, subjects in precontemplation stage found that taste was more important, whereas people in maintenance stage found that health was more important. CONCLUSIONS: The stages of change model makes a useful distinction between people with different attitudes towards nutrition and health. Nutrition education can benefit from this distinction.

Adolescent↗
PubMed1987

Cyclopropane amino acid ester dipeptide sweeteners.

A series of esters of L-aspartyl-1-aminocyclopropane carboxylic acid has been prepared and their sweet tastes determined. The sweetest ester prepared was about 300 times sweeter than sucrose. An attempt to use basic conditions during preparation of the dipeptide allyl ester led to succinimide formation of the aspartyl peptide even though the beta-carboxyl group was protected by a t-butyl ester function. The X-ray structure of the propyl ester (1c) was determined and its conformation is discussed.

Aspartame↗
PubMed2006

Transient receptor potential family members PKD1L3 and PKD2L1 form a candidate sour taste receptor.

Animals use their gustatory systems to evaluate the nutritious value, toxicity, sodium content, and acidity of food. Although characterization of molecular identities that receive taste chemicals is essential, molecular receptors underlying sour taste sensation remain unclear. Here, we show that two transient receptor potential (TRP) channel members, PKD1L3 and PKD2L1, are coexpressed in a subset of taste receptor cells in specific taste areas. Cells expressing these molecules are distinct from taste cells having receptors for bitter, sweet, or umami tastants. The PKD2L1 proteins are accumulated at the taste pore region, where taste chemicals are detected. PKD1L3 and PKD2L1 proteins can interact with each other, and coexpression of the PKD1L3 and PKD2L1 is necessary for their functional cell surface expression. Finally, PKD1L3 and PKD2L1 are activated by various acids when coexpressed in heterologous cells but not by other classes of tastants. These results suggest that PKD1L3 and PKD2L1 heteromers may function as sour taste receptors.

Calcium↗
PubMedDate not supplied

Adequate peritoneal dialysis: theoretical model and patient treatment.

The objective of this study was to evaluate the relationship between adequate PD with sufficient weekly Kt/V (2.0) and Creatinine clearance (CCR) (60l) and necessary daily dialysate volume. This recommended parameter was the result of a recent multi-centre study (CANUSA). For this there were 40 patients in our hospital examined and compared in 1996, who carried out PD for at least 8 weeks and up to 6 years. These goals (CANUSA) are easily attainable in the early treatment of many individuals with a low body surface area (BSA). With higher BSA or missing RRF (Residual Renal Function) the daily dose of dialysis must be adjusted. We found it difficult to obtain the recommended parameters and tried to find a solution to this problem. The simplest method is to increase the volume or exchange rate. The most expensive method is to change from CAPD to APD with the possibility of higher volume or exchange rates. Selection of therapy must take into consideration: 1. patient preference, 2. body mass, 3. peritoneal transport rates, 4. ability to perform therapy, 5. cost of therapy and 6. risk of peritonitis. With this information in mind, an individual prescription can be formulated and matched to the appropriate modality of PD.

Body Surface Area↗
PubMed2002

The neuroanatomical axis for control of energy balance.

The hypothalamic feeding-center model, articulated in the 1950s, held that the hypothalamus contains the interoceptors sensitive to blood-borne correlates of available or stored fuels as well as the integrative substrates that process metabolic and visceral afferent signals and issue commands to brainstem mechanisms for the production of ingestive behavior. A number of findings reviewed here, however, indicate that sensory and integrative functions are distributed across a central control axis that includes critical substrates in the basal forebrain as well as in the caudal brainstem. First, the interoceptors relevant to energy balance are distributed more widely than had been previously thought, with a prominent brainstem complement of leptin and insulin receptors, glucose-sensing mechanisms, and neuropeptide mediators. The physiological relevance of this multiple representation is suggested by the demonstration that similar behavioral effects can be obtained independently by stimulation of respective forebrain and brainstem subpopulations of the same receptor types (e.g., leptin, CRH, and melanocortin). The classical hypothalamic model is also challenged by the integrative achievements of the chronically maintained, supracollicular decerebrate rat. Decerebrate and neurologically intact rats show similar discriminative responses to taste stimuli and are similarly sensitive to intake-inhibitory feedback from the gut. Thus, the caudal brainstem, in neural isolation from forebrain influence, is sufficient to mediate ingestive responses to a range of visceral afferent signals. The decerebrate rat, however, does not show a hyperphagic response to food deprivation, suggesting that interactions between forebrain and brainstem are necessary for the behavioral response to systemic/ metabolic correlates of deprivation in the neurologically intact rat. At the same time, however, there is evidence suggesting that hypothalamic-neuroendocrine responses to fasting depend on pathways ascending from brainstem. Results reviewed are consistent with a distributionist (as opposed to hierarchical) model for the control of energy balance that emphasizes: (i) control mechanisms endemic to hypothalamus and brainstem that drive their unique effector systems on the basis of local interoceptive, and in the brainstem case, visceral, afferent inputs and (ii) a set of uni- and bidirectional interactions that coordinate adaptive neuroendocrine, autonomic, and behavioral responses to changes in metabolic status.

Animals↗