Oral zinc sulfate solutions inhibit sweet taste perception

We investigated the ability of zinc sulfate (5, 25, 50 mM) to inhibit the sweetness of 12 chemically diverse sweeteners, which were all intensity matched to 300 mM sucrose [800 mM glucose, 475 mM fructose, 3.25 mM aspartame, 3.5 mM saccharin, 12 mM sodium cyclamate, 14 mM acesulfame-K, 1.04 M sorbitol, 0.629 mM sucralose, 0.375 mM neohesperidin dihydrochalcone (NHDC), 1.5 mM stevioside and 0.0163 mM thaumatin]. Zinc sulfate inhibited the sweetness of most compounds in a concentration dependent manner, peaking with 80% inhibition by 50 mM. Curiously, zinc sulfate never inhibited the sweetness of Na-cyclamate. This suggests that Na-cyclamate may access a sweet taste mechanism that is different from the other sweeteners, which were inhibited uniformly (except thaumatin) at every concentration of zinc sulfate. We hypothesize that this set of compounds either accesses a single receptor or multiple receptors that are inhibited equally by zinc sulfate at each concentration.     

On the sense of taste in two Malagasy Primates (Microcebus murinus and Eulemur mongoz)

The relationship between phylogeny and taste is of growing interest.In this study we present recordings from the chorda tympaniproper (CT) nerve of two lemuriforme primates, the lesser mouselemur (Microcebus murinus) and the mongoose lemur (Eulemur mongoz),to an array of taste stimuli which included the sweeteners acesulfame-K,alitame, aspartame, D-glucose, dulcin, monellin, neohesperidindihydrochalcone (NHDHC), saccharin, sodium superaspartame, stevioside,sucralose (TGS), sucrose, suosan, thaumatin and xylitol, aswell as the non–sweet stimuli NaC1, citric acid, tanninand quinine hydrochloride. In M.murinus the effects of the tastemodifiers gymnemic acid and miraculin on the CT response wererecorded. Conditioned taste aversion (CTA) experiments in M.murinusand two-bottle preference (TBP) tests in E.mongoz were alsoconducted. We found that all of the above tastants except thaumatinelicited a CT response in both species. The CTA technique showedthat M.murinus generalized from sucrose to monellin but notto thaumatin. The intake of aspartame, ranging in concentrationfrom 0.1 to 30 mM was measured in E.mongoz with TBP tests. Atno concentration did we see a preference, but there was a significantrejection of 10 and 30 mM aspartame (P     

On the gustatory effect of amiloride in the monkey (Macaca mulatto)

Amiloride suppressed the summated chorda tympani proper nerveresponses to NaCl and LiCl in rhesus monkeys but did not suppressthe responses to sucrose, acesulfame-K, aspartame, Na-saccharin,Na-cyclamate, xylitol, D-glucose, D-fructose, glycine, KCl andNH₄Cl.     

Behavioral study in the gray mouse lemur (Microcebus murinus) using compounds considered sweet by humans

This study presents the results from two-bottle preference (TBP) tests performed on the gray mouse lemur (Microcebus murinus), a small Malagasy primate. We found that of 18 compounds considered sweet by humans, M. murinus preferred only six: D-tryptophan, dulcin, fructose, sucrose, SC45647, and xylitol. The animals neither preferred nor rejected acesulfame-K, alitame, aspartame, N-4-cyanophenyl-N'-cyanoguanidineacetate (CCGA), cyanosuosan, cyclamate, monellin, saccharin, suosan, super-aspartame, N-trifluoroacetyl-L-glutamyl-4-aminophenylcarbonitrile (TGC), and thaumatin. Together with previously recorded taste-nerve responses in M. murinus to acesulfame-K, alitame, aspartame, cyclamate, monellin, saccharin, and suosan [Hellekant et al., Chem Senses 18:307-320, 1993b], the current results suggest that these compounds either do not taste sweet to M. murinus or they have an aversive taste component. In this work we also relate these findings to phylogeny.     

Quantitative and qualitative evaluation of high-intensity sweeteners and sweetener mixtures

High intensity sweeteners were evaluated for sweetness and bitternessintensity using time-intensity scaling. Mean intensities of50:50 mixtures as well as the single sweeteners were used tocompute predicted scores which were compared to the observedscores as a means of evaluating additivity in the mixtures.Concentration-dependent effects of subadditivity, additivityand hyperadditivity were observed within some sweetener pairs,but these did not follow any consistent pattern across sweeteners.Synergy, a special case of hyperadditivity evaluated by comparingpredicted to observed scores, was seen in mixtures of aspartameand acesulfame-K at all concentrations. Aspartame/saccharinblends were synergistic only at the lowest concentration tested,despite the structural similarity between acesulfame-K and saccharin.Blends of sucrose/aspartame and acesulfame-K/saccharin did notexhibit synergy. Comparisons based on ratings of initial sweetnessrather than the whole time-intensity curve, reflected previousfindings of synergy in some sweetener pairs.     

EFFECTS OF DISCONFIRMED CONSUMER EXPECTATIONS ON FOOD ACCEPTABILITY

Three studies were conducted to assess the effects of disconfirmed consumer expectations on food acceptability. In the first, disconfirmed expectations for the sensory attributes of an edible film had a negative effect on acceptability of the film. Greater disconfirmation resulted in lower acceptance and purchase intent. In the second study, written product information was used to establish three levels of expected acceptability and expected bitterness for a novel fruit beverage. Comparison of preexposure (expected) and postexposure (perceived) ratings of acceptability and bitterness supported an assimilation model of disconfirmation effects for conditions in which expectations of acceptability were high and expectations of bitterness were low. A contrast effect was observed for bitterness judgments when expectations of bitterness were high. Associative effects resulting from the expectation manipulation were observed on other sensory attributes. In the third study, expectations were manipulated to influence both direction (positive versus negative) and degree of disconfirmation for the acceptance of cola beverages. Results provided further support for an assimilation model of these effects.     

An Equiratio Mixture Model for Non-additive Components: A Case Study for Aspartame/Acesulfame-K Mixtures

The Equiratio Mixture Model predicts the psychophysical functionfor an equiratio mixture type on the basis of the psychophysicalfunctions for the unmixed components. The model reliably estimatesthe sweetness of mixtures of sugars and sugar-alchohols, butis unable to predict intensity for aspartame/sucrose mixtures.In this paper, the sweetness of aspartame/acesulfame-K mixturesin aqueous and acidic solutions is investigated. These two intensivesweeteners probably do not comply with the model's originalassumption of sensory dependency among components. However,they reveal how the Equiratio Mixture Model could be modifiedto describe and predict mixture functions for non-additive substances. To predict equiratio functions for all similar tasting substances,a new Equiratio Mixture Model should yield accurate predictionsfor components eliciting similar intensities at widely differingconcentration levels, and for substances exhibiting hypo- orhyperadditivity. In addition, it should be able to correct violationsof Stevens's power law. These three problems are resolved ina model that uses equi-intense units as the measure of physicalconcentration. An interaction index in the formula for the constantaccounts for the degree of interaction between mixture components.Deviations from the power law are corrected by a nonlinear responseoutput transformation, assuming a two-stage model of psychophysicaljudgment. Chem. Senses 21: 1–11, 1996.     

A test of fruit varieties on entry rate and development by neonate larvae of the codling moth,Cydia pomonella

The rate of entry by neonate larvae of the frugivorous codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), into fruit material was investigated. We used no‐choice bioassays in climate‐controlled rooms to assay larval entry across four host plant species (apple, pear, quince, walnut) and three varieties within a single fruit species (apple). Larvae successfully entering apples were reared to adulthood, and we collected tissue samples from apples which were successfully colonized in order to determine sucrose concentrations. This information was used to evaluate differences in adult moth size, development time, and pulp sucrose concentration due to apple variety. Four important findings emerged: (1) neonate larvae had the highest frequency of entry (86% of larvae) into apple fruits, compared with pear (78%), quince (56%), and walnut (32%); (2) the frequency of larval entry into immature apples differed across apple varieties, and larval entry rate was highest in variety Golden Delicious (72%), compared with Granny Smith (46%) and Red Delicious (64%); (3) on average, adult moths were larger and development times were shorter on the variety with the highest entry frequency (Golden Delicious); and (4) apple pulp sucrose concentrations were higher for Golden Delicious (17.5 μg mg^?1) than for either Granny Smith (15.9 μg mg^?1) or Red Delicious (15.1 μg mg^?1) varieties, which correlates positively with entry and development data. We conclude that host fruit species and varietals within a species affect the entry rate of neonate codling moth larvae in no‐choice assays. We hypothesize that larval development is influenced by mean sucrose concentrations or other phytochemical differences associated with host fruit varieties.     

Preference for sucralose predicts behavioral responses to sweet and bittersweet tastants

Rats can be classified as either sucralose avoiders (SA) or sucralose preferrers (SP) based on their behavioral responses in 2-bottle preference, 1-bottle intake, and brief-access licking tests. The present study demonstrates that this robust phenotypic variation in the preference for sucralose predicts acceptance of saccharin, an artificial sweetener with a purported concentration-dependent "bitter" side taste and a 0.25 M sucrose solution adulterated with increasing concentrations of quinine hydrochloride (QHCl). Specifically, SA displayed decreased preference for and intakes of saccharin (≥41.5 mM) and sucrose-QHCl (>0.5 mM QHCl) solutions, relative to SP. In a second experiment involving brief-access (30-s) tests, SP and SA did not differ in their unconditioned licking responses across a range of sodium chloride or QHCl solutions (0.03-1 mM). However, the acceptability threshold for sucrose was lower in SA, relative to SP (0.06 and 0.13 M, respectively). Our findings suggest that phenotypic differences in sucralose preference are indicative of a more general difference in the hedonic processing of stimuli containing "bittersweet" or "sweet" taste qualities.     

THE EFFECTS OF SUGARS AND ACIDS ON CONSUMER ACCEPTABILITY OF KIWIFRUIT

A kiwifruit (Actinidia deliciosa (A Chev) Liang et Ferguson cv Hayward) pulp was made using fruit harvested immature to minimize the presence of aroma volatiles. This pulp was modified by incorporating sugars and acids to simulate kiwifruit with a range of Brix and acid levels. Using sensory evaluation, flavor acceptability was found to increase with increasing Brix. As expected, perceived " sweetness intensity" increased with increasing Brix. Acidity did not influence flavor acceptability. At high Brix, sugars were able to suppress the effects of variations in acidity. Changes in Brix did not influence " flavor intensity", suggesting that aroma volatiles may be important contributors to kiwifruit flavor intensity.     

Carbohydrate availability affects growth and metabolism in peach fruit

Along with sucrose, sorbitol represents the main photosynthetic product and form of translocated carbon in peach. This study aimed at determining whether peach fruit carbohydrate metabolism is affected by changes in source–sink balance , and specifically whether sorbitol or sucrose availability regulates fruit enzyme activities and growth. In various trials, different levels of assimilate availability to growing fruits were induced in vivo by varying crop load of entire trees, leaf : fruit ratio (L:F) of fruiting shoots, or by interrupting the phloem stream (girdling) to individual fruits. In vitro, fruit tissue was incubated in presence/absence of sorbitol and sucrose. Relative growth rate (RGR), enzyme activities and carbohydrates were measured at different fruit growth stages of various peach cultivars in different years. At stage III, high crop load induced higher acid invertase (AI, EC 3.2.1.26) activities and hexose : sucrose ratios. Both sorbitol and sucrose contents were proportional to L:F, while sorbitol dehydrogenase (SDH, EC 1.1.1.14) activity was the only enzyme activity directly related to L:F in both fruit growth stages. Girdling reduced fruit RGR and all major carbohydrates after 4 days and SDH activity already after 48 h, but it did not affect sucrose synthase (SS, EC 2.4.1.13), AI and neutral invertase (NI, EC 3.2.1.27). Fruit incubation in sorbitol for 24 h induced higher SDH activities than in buffer alone. In general, assimilate availability affected both sorbitol and sucrose metabolism in peach fruit, and sorbitol may function as a signal for modulating SDH activity. Under highly competitive conditions, AI activity may be enhanced by assimilate depletion, providing a mechanism to increase fruit sink strength by increasing hexose concentrations.     

Gustatory responses in three prosimian and two simian primate species (Tupaia glis, Nycticebus coucang, Galago senegalensis, Callithrix jacchus jacchus and Saguinus midas niger) to six sweeteners and miraculin and their phylogenetic implications

The intake of six sweeteners was recorded together with theireffects on the impulse activity of the chorda tympani propernerve during their application to the tongue. The sweetenerswere: acetosulfam, aspartame, D-tryptophan, glycine, xylitoland thaumatin. They were used at human equi-sweet concentrations.In all species, D-tryptophan was strongly preferred and gavea significant response, while aspartame and thaumatin gave neithera significant behavioral nor a significant neural response.Acetosulfam, glycine and xylitol elicited neural responses,but their behavioral effects differed from a rejection in somespecies to a preference in others. Miraculin, which has a sweetnessinducing effect in man, showed this effect only in the platyrrhineanspecies and not in the prosimian.     

双歧杆菌发酵番茄生产保健饮料

以新鲜的番茄为原料,加工成番茄汁后,采用双歧杆菌发酵生产制成保健饮料,通过单因素及正交实验确定最佳发酵条件为:菌种添加量为4%,发酵温度37℃,发酵时间10 h,原汁质量分数60%;辅料添加量:果胶0.15%,PGA0.1%,黄原胶0.1%,磷酸二氢钠0.05%;产品调配的最佳配方为:蜂蜜4%,蔗糖3%,水果香精2%     

Female rats show a bimodal preference response to the artificial sweetener sucralose

The preference of female Sprague-Dawley rats for sucralose, a non-nutritive sweetener derived from sucrose, was evaluated in 23 h two-bottle tests with water or saccharin. Overall, the rats displayed weak or no preferences for sucralose (0.25-4 g/l) over water but strong preferences for saccharin (0.5-8 g/l) over water and saccharin (1 g/l) over sucralose (0.5 g/l). The rats also preferred a saccharin + sucrose mixture to sucrose, but sucrose to a sucralose + sucrose mixture. There were marked individual differences in sucralose preferences: about half the rats preferred sucralose to water at some concentrations while most remaining rats avoided sucralose. Both subgroups preferred saccharin to sucralose. Sucralose appears to have an aversive off-taste that reduces its palatability to rats.     

Carbohydrate metabolism in Musa paradisiaca

Considerable variations exist in the content of glucose, fructose, sucrose, starch and protein and in the activities of enzymes involved in carbohydrate metabolism between different parts of the banana plant (Musa paradisiaca). Sucrose synthetase is present in the highest concentration in rootstock and fruit pulp, and sucrose phosphate synthetase in the pseudostem. The highest ratio of the activity of sucrose phosphate synthetase to sucrose synthetase is found in leaves. Acid invertase is present in leaves, leaf-sheath and fruit pulp and is not demonstrable in rootstock and pseudostem. Neutral invertase activity is high in pseudostem and leaf-sheath. Starch phosphorylase is largely concentrated in fruit pulp and rootstock. The maximum activity of ATP:d-phosphoglucose (ADPG) pyrophosphorylase is found in rootstock. β-Amylase is not demonstrable in rootstock and is largely concentrated in leaf-sheath. Hexokinase is most active in rootstock and the lowest in leaves. Acid phosphatase and alkaline phosphatase activity is highest in fruit pulp and pseudostem. Glucosephosphate isomerase is most active in the rootstock and lowest in the leaves.     

Determination of complex polysaccharides by HPAE-PAD in foods: validation using accuracy profile

The increasing supplementation of foods with carbohydrates substitutes and the growing regulatory requirements for controlling these products, turn into the necessary development and validation of accurate analytical control techniques. This paper presents the simultaneous validation of two close analytical procedures for the determination of sucralose and fructooligosaccharides (FOS) in fruit juices using high-performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD). This study consisted in applying the accuracy profile procedure with a three-level validation experimental design. Decision criteria, namely acceptability limits (+/-10%) and proportion of result contained in the calculated tolerance intervals (80%), were decided on a consensus basis with end-users, whereas no official references were available. In conclusion, the proposed analytical procedures were validated over the selected validation domains for fruit juices and came out on very capable techniques. Validation strategy was purposely oriented towards the ease of use in routine and the liability of the methods rather than extreme performances. This objective is consistent with this of contract laboratories which need to reach a known level of guarantee for the results which they produce. In that respect, accuracy profile represents a very convenient tool to ascertain such a goal.     

The Sweet Passion Fruit (<Emphasis Type="Italic">Passiflora alata</Emphasis>) Crop: Genetic and Phenotypic Parameter Estimates and QTL Mapping for Fruit Traits

Despite their economic importance, some tropical crop species are largely neglected when it comes to conducting genetic studies characterizing target traits for breeding. Herein, genetic and phenotypic parameters as well quantitative trait loci (QTL) are described for the first time in a full-sib progeny of sweet passion fruit (Passiflora alata). A hundred F₁ individuals were evaluated in two locations for seven fruit traits: diameter of fruit (DF, in mm), length of fruit (LF, in mm), weight of fruit (WF, in g), thickness of fruit skin (TS, in mm), weight of fruit skin (WS, in g), weight of fruit pulp (WP, in g) and soluble solids (SS, in °Brix). Mixed models fitted complex, unstructured genetic variance-covariance matrices for all traits in phenotypic analysis. Because of important genetic correlations among skin and pulp traits, multiplicative index selection to select the most promising individuals was successfully applied. A previously reported integrated map supported composite interval mapping (CIM) analyses. In total, we found 22 QTLs mapped in seven out of nine linkage groups. Heritabilities (from 59.8 % to 82.7 %) and proportion of phenotypic variance explained by the QTLs (from 42.0 % to 64.3 %) were comparable for each trait. Principal component analysis on TS, WS and WP showed that the first two principal components (PCs) accounted for 93.6 % of the total variability. CIM analyses on these two PCs revealed five putative QTLs controlling variation for these three traits simultaneously. Thus, genetic improvement for sweet passion fruit should be based on correlations between traits and QTL-related information can be a useful tool.     

Optimization of extraction of high-ester pectin from passion fruit peel (Passiflora edulis flavicarpa) with citric acid by using response surface methodology

A central composite design was employed to optimize the extraction of pectin with citric acid. The independent variables were citric acid concentration (0.086–2.91% w/v) and extraction time (17–102 min). The combined effect of these variables on the degree of esterification was investigated. Results have shown that the generated regression models adequately explained the data variation and significantly represented the actual relationship between the independent variables and the responses. Besides that, the citric acid concentration was the most important factor to affect the degree of esterification, as it exerted a significant influence on the dependent variable. Lower citric acid concentration increased the pectin degree of esterification. The surface response showed the relationships between the independent variables, and thus responses were generated. Through this surface, the satisfactory condition of 0.086% w/v citric acid for 60 min was established for extraction of high-ester yellow passion fruit pectin.