Time-Intensity Evaluation of Sweetness and Fruitiness and Their Interaction in a Model Solution

Sweetness and fruitness were evaluated by time-intensity (TI) procedures in solutions varying in concentrations of glucose and peach essence at two temperatures. Of the eleven TI parameters quatified to characterize the TI curves, ten parameters varied significantly across samples for sweetness, whereas only seven varied significantly for fruitiness. Maximum sweetness intensity increased as glucose or peach essence concentration or solution temperature was raised. In contrast, maximum fruitiness intensity increased only with an increase in peach flavor concentration. Although the total persistence of aftertaste did not differ significantly between the two attributes, the mean time to maximum intensity for sweetness (6.6 sec) was 3.8 sec shorter than that found for fruitiness.     

‘Different-stimulus’ scaling errors; effects of scale length

Using a Rank-Rating protocol and a traditional protocol whereby stimuli could not be re-tasted nor the scores be reviewed and modified, judges’ performance on category and line scales of intensity, in terms of the number of ‘different-stimulus’ scaling errors, was compared. A different stimulus scaling error was defined as giving a perceptually more intense stimulus an equal or lower score than a perceptually less intense stimulus. The scales compared were 9- and 20-point category scales and 10 and 20 cm line scales. The stimuli were beef flavored soups of varying saltiness and orange flavored gelatin cubes of varying sweetness. There was a tendency for longer scales (20-point category, 20 cm line) to yield fewer ‘different-stimulus’ scaling errors than the shorter scales (9-point category, 10 cm line).     

Sweet taste and solution properties of α,α-trehalose

α,α-Trehalose, a naturally occurring non-reducing disaccharide (α, D-glucopyranosyl 1–1 α-D-glucopyranoside) is investigated by solution parameters and sensorial effects. Interactions between α, α-trehalose and water give rise to hydration effects which are measurable by intrinsic viscosity [n], apparent specific volume V°₂, and NMR relaxation times. Water-solute interactions are prime determinants of taste qualities. An interpretation of sweetness intensity and persistence of α,α-trehalose is therefore offered, based on its solution properties and its effect on water structure. From the results, it appears that α,α-trehalose undergoes a better packing among water molecules than other sugars. α,α-Trehalose is found to be less sweet but more persistent than sucrose, fructose, glucose or maltose.     

Taste properties of cocoa drinks with an added bitter/sweet sugar: intensity/time effects

Cocoa drinks treated with either sucrose or the bitter/sweet sugar, methyl α-D-mannopyranoside were evaluated for their intensity/time response determined by taste panellists using a moving chart recorder. Both additives caused an increase in persistence as well as intensity of response, sucrose for sweetness and methyl α-D-mannopyranoside for bitterness.
Tasting of the sucrose-treated drinks, after presaturating panellists' tongues with quinine sulphate solutions, caused no significant differences in perceived sweetness. However, presaturating panellists' tongues with sucrose solution did cause significant differences in bitterness perception of the drinks containing methyl α-D-mannopyranoside.
These results accord with a previous observation of the taste response to methyl α-D-mannopyranoside in pure water and suggest that the bitter/sweet molecule may exert its effect by simultaneously spanning both basic taste receptors.     

Gluten‐free bread: multiple time–intensity analysis,physical characterisation and acceptance test

The formulation of gluten‐free breads is challenging, once the gluten network is responsible for the physical and sensory properties of bread. This study presents a novel concept for making gluten‐free breads using sugar substitutes. The quality of gluten‐free breads was analysed by means of physical (specific volume and colour), textural (firmness, elasticity and chewiness) and sensory properties (time‐intensity analysis and acceptance test). Time‐intensity analysis showed that the sample developed with raw sugar had a higher intensity of sweetness, and the sample with stevia had a higher intensity of yeast flavour. The sample with frutooligosaccharides (FOS) presented a higher acceptance by consumers. Sample with stevia presented the higher intensity of yeast flavour (8.10) and the lesser mean of specific volume (2.83 cm³.g^?1); whereas sample with sugar who presented higher intensity of sweetness stimulus (5.20) also presented the higher mean of specific volume (3.80 cm³.g^?1). The addition of prebiotic and sweetener opens up new opportunities to develop gluten‐free breads that may present similar properties to those of wheat‐based breads.     

Sugar Composition and Flavor Quality of High Sugar (Shrunken) and Normal Sweet Corn

Soluble sugar composition of the corn kernel in a shrunken (high sugar) variety, ‘Xtra Sweet 77′, and a normal sweet variety, ‘Jubilee’ was determined after freezing a corn-on-cob product at two levels of commercial harvest maturity by HPLC and enzymic methods of analysis. Sucrose, glucose and fructose were found in measurable amounts by both methods. The less mature sample of either variety contained the higher level of each sugar, at a sucrose:glucose:fructose ratio of approximately 15:1:1 in ‘Jubilee’ and 20:1:1 in ‘Xtra Sweet 77′. Sensory evaluation showed ‘Xtra Sweet 77’ which contained nearly twice the total sugars of ‘Jubilee’ to be sweeter. Sweetness differences between maturity samples within a variety were not significant, nor was there a consistent preference shown for the higher sweetness or overall quality of the ‘Xtra Sweet 77’ samples. Sensory perception of sweetness was most highly correlated with sucrose content.     

POSTHARVEST QUALITY AND SENSORY ATTRIBUTES OF ‘BYRONGOLD’ AND ‘RUBYSWEET’ PLUMS1

Fruit from two new cultivars of plums, ‘Byrongold’ and ‘Rubysweet’ were harvested at three maturities. Maturity one and two were ripened for three and six days at 20C and 85% relative humidity to determine fruit quality characteristics during storage. Plums were separated into three maturity categories by delayed light emission. Fruit size, weight, hue angle, flesh firmness, soluble solids and concentration of sugars, organic acids and sensory attributes were determined to evaluate stroage quality of the fruit. Significant differences were found between cultivars for sucrose, glucose, fructose and sorbitol. Sugar concentrations varied within the same cultivar by maturity and storage times. In general, acid levels decreased as plums ripened. Panelists preferred “Byrongold” ripened for three days for tartness and juiciness and “Byrongold” ripened for six days for sweetness. “Rubysweet” ripened for three days was preferred for sweetness, tartness and juiciness. Significant differences were found in peel bitterness between cultivars and days ripened. Unripened maturity 2 ‘Byrongold’ and unripenedd maturity 3 ‘Rubysweet’ had the highest peel bitterness. Hedonic scores showed ‘Rubysweet’.     

Sugars and acids of strawberry varieties

The sugar and acid compositions of six strawberry (Fragaria×ananassa Duch.) varieties from 1997 and 1998, grown in different conditions, 26 samples in all, were investigated by GC as trimethylsilyl derivatives. The major sugars were glucose (1.89–4.52?g/100?ml), fructose (2.14–4.14?g/100?ml) and sucrose (0.90–3.87?g/100?ml), the major acids being citric (0.73–1.58?g/100?ml) and malic (0.22–0.69?g/100?ml). Total sugar content (glucose+fructose+sucrose) varied from 5.35?g/100?ml to 10.96?g/100?ml in accordance with soluble solids (°Brix). The correlation between them showed a linear regression y=0.873x-0.420, the percentage of determination of the regression model being 82.1%. Among one variety only, ‘Senga Sengana’, the percentage of the model was 86.9%. No significant differences were found between the strawberries from conventional versus those from organic farms. Contents of sugars and soluble solids were lower in varieties ‘Jonsok’ and ‘Honeoye’ than in ‘Korona’, ‘Bounty’ and ‘Polka’. The concentrations of malic acid were significantly higher in Senga Sengana, Jonsok and Bounty than in other varieties.     

Compression resistance,sweetener's diffusion and sweetness of hydrocolloids gels

The effects of the type and concentration of two hydrocolloids—κ-carrageenan and gellan gum—and of the type and concentration of two sweeteners—sucrose and aspartame—on the gel resistance to compression, on the sweetener diffusion and on the intensity of the gel sweetness and the relationships between the gel physical properties and their perceived sweetness were studied. The gels true rupture stress increased with hydrocolloid concentration, this increase being higher for gellan gels. Gellan gels showed lower true rupture strain values, which in contrast with carrageenan gels, decreased on increasing hydrocolloid concentration. The addition of sucrose produced a bigger increase in gel strength at the higher hydrocolloid concentration. The main effect detected on the sweeteners’ diffusion constant was the higher value observed in low concentration (3 g L⁻¹) κ-carrageenan gels. Gellan gels were perceived as sweeter than κ-carrageenan gels. The decrease in sweetness due to an increase in hydrocolloid concentration was greater in gellan than in carrageenan gels. Variations in sweetener concentration, true rupture strain, and deformability modulus values explained 93% of the variability in sweetness for gels with sucrose and 94% for gels with aspartame.     

The Influence of the Rebaudioside A Content of Stevia (Stevia rebaudiana Bertoni) on the Determination of Sweetness Equivalence in Bittersweet Chocolates,Using the Time‐Intensity Analysis

The consumption of diet products has increased greatly in recent years. The objectives of the study were to develop a bittersweet chocolate added inulin and stevias with different rebaudioside A contents (60%, 80%, and 97%). Five chocolate samples were formulated with different sucrose concentrations to determine the ideal sucrose concentration for bittersweet chocolate. The use of just‐about‐right scale identified an ideal sucrose concentration of 47.5% (w/w). The sweetness equivalence in sugar‐free bittersweet chocolates was determined by the time–intensity method by 14 selected and trained judges. The data collected during each session of sensory evaluation furnished the following parameters in relation to the sweet stimulus: Imax (maximum intensity recorded), Timax (time at which the maximum intensity was recorded), Area (area of time × intensity curve), and Ttot (total duration time of the stimulus). The time–intensity analysis indicated that the percentages of rebaudioside A did not interfere with the sweetness intensity of the sweetener stevia in bittersweet chocolate and there was no significant difference in the concentrations tested (0.16%, 0.22%, 0.27%) of each stevia, in relation to the parameters evaluated. In addition, the reduction in fat content did not alter the perception of the sweetness intensity of the samples. These results showed important information to research and development of chocolate products. Therefore, the use of the lowest stevia concentration tested (0.16%) is the most indicated for use, since this quantity was sufficient to reach the ideal sweetness of the product, so there was no point in adding more.     

黄土高原旱塬区不同品种苹果果实糖及有机酸含量比较分析

为明确黄土高原旱塬区不同品种苹果果实中糖与有机酸含量的特征,对主栽的30个品种果实中糖、酸类物质含量进行分析。采用高效液相色谱法（High-phase liquid chromatography,HPLC）对30个品种成熟期果实中可溶性糖与有机酸含量进行了测定,并对数据进行单因素方差分析与相关性分析。结果表明:不同品种苹果果实糖组分中果糖含量最高,均值为52.964 mg/g,占总糖含量的48.82%,且二者呈极显著性相关（r=0.787）,果糖含量最高的品种为‘嘎啦’（69.736 mg/g）,大部分品种果实中蔗糖含量高于葡萄糖含量,只有3个品种表现出葡萄糖含量高于蔗糖含量,分别为‘金冠’、‘八月富士’和‘无锈金矮生’;不同品种苹果果实酸组分中苹果酸含量最高,均值为3.857 mg/g,占总酸含量的57.44%,且二者呈极显著性相关（r=0.845）,奎宁酸含量次之,其他种类有机酸含量较低,苹果酸含量最高的品种为‘寒富’（8.109 mg/g）;甜度值/总酸含量大于30的品种有3个,分别为‘世界1号’、‘金冠’和‘嘎啦’,介于20～30之间的品种有13个,小于20的品种有14个。苹果果实中甜度值和总酸含量、以及甜度值与总酸含量的比值共同影响果实风味。     

Regulation of alcoholic fermentation in batch and chemostat cultures of Kluyveromyces lactis CBS 2359

Kluyveromyces lactis is an important industrial yeast, as well as a popular laboratory model. There is currently no consensus in the literature on the physiology of this yeast, in particular with respect to aerobic alcoholic fermentation (‘Crabtree effect’). This study deals with regulation of alcoholic fermentation in K. lactis CBS 2359, a proposed reference strain for molecular studies. In aerobic, glucose-limited chemostat cultures (D=0·05–0·40 h⁻¹) growth was entirely respiratory, without significant accumulation of ethanol or other metabolites. Alcoholic fermentation occurred in glucose-grown shake-flask cultures, but was absent during batch cultivation on glucose in fermenters under strictly aerobic conditions. This indicated that ethanol formation in the shake-flask cultures resulted from oxygen limitation. Indeed, when the oxygen feed to steady-state chemostat cultures (D=0·10 h⁻¹) was lowered, a mixed respirofermentative metabolism only occurred at very low dissolved oxygen concentrations (less than 1% of air saturation). The onset of respirofermentative metabolism as a result of oxygen limitation was accompanied by an increase of the levels of pyruvate decarboxylase and alcohol dehydrogenase. When aerobic, glucose-limited chemostat cultures (D=0·10 h⁻¹) were pulsed with excess glucose, ethanol production did not occur during the first 40 min after the pulse. However, a slow aerobic ethanol formation was invariably observed after this period. Since alcoholic fermentation did not occur in aerobic batch cultures this is probably a transient response, caused by an imbalanced adjustment of enzyme levels during the transition from steady-state growth at μ=0·10 h⁻¹ to growth at μ_max. It is concluded that in K. lactis, as in other Crabtree-negative yeasts, the primary environmental trigger for occurrence of alcoholic fermentation is oxygen limitation. © 1998 John Wiley & Sons, Ltd.     

The Production and Properties of Glucose Syrups. III. Sweetness of Glucose Syrups and Related Carbohydrates

A series of glucose syrups, before and after hydrogenation, were assessed for sweetness at concentrations of 10% and 20%. Only in the cases of 21% D. E. glucose syrup and D-glucose was there no significant increase in sweetness at 10% after hydrogenation and at 20%, only with D-glucose. These results contrast with a previous report. Hydrogenation of mono- and disaccharides, except D-glucose and cellobiose, resulted in increased sweetness. Various theories are proposed to explain the results.     

Maturity and ripening effects on chemical and sensory properties of apple juice

The effects of harvest maturity and ripening on the chemical composition and sensory characteristics of ‘McIntosh’ and ‘Spartan’ apple juice were evaluated. Juice was extracted from fruit harvested at seven weekly intervals beginning 3–4 weeks before commercial harvest and from fruit held in air storage (1°C) for 1 to 3 months. Internal ethylene concentration and starch index were used as maturity indices. Principal component analysis of juice data (pH. titratable acidity, organic acids, soluble solids, sugars, phenols, turbidity, and Hunterlab colour) showed a distinctive maturity effect on the characteristics of juice extracted from fruit immediately after harvest or after storage. Triangle testing showed aroma and flavour differences in both ‘McIntosh’ and ‘Spartan’ to be first discernable when ethylene was first detected (internal ethylene concentration ≥ 0.1 μl litre^?1) and starch hydrolysis evident (starch index 3.0–5.0 for ‘McIntosh’, 1.5–3.0 for ‘Spartan’), or after 2–3 months of air storage. Sensory profiling of fruity aroma, total aroma, fruit flavour by mouth, sweetness, and sourness in the juices showed increased fruitiness and sweetness and decreased sourness with advancing maturity.     

Sugars and sweetness in buttercup squash

Sweetness is an important attribute in the flavour, acceptability, and perceived quality of winter squash. Glucose, fructose and sucrose contributed differently to the perceived sweetness of eight winter squash cultivars (Cucurbita maxima) rated by a trained sensory panel. Sucrose was the most important sugar in predicting sweetness, but better predictions were obtained using additional combinations of glucose and fructose content. Sugar content and relative proportions of glucose, fructose and sucrose changed during storage. Starch content decreased for all cultivars during storage, and was an important predictor of sweetness for high starch cultivars only. When data for sweetness were regressed against sugar concentrations, adjusted R² values in the range of 0.68–0.89 were obtained for seven of the cultivars. Including starch in the regression models unproved the adjusted R² values to 0.77–0.94.     

Amount of characteristic compounds in 15 cultivars of onion (Allium cepa L.) in controlled field trials

BACKGROUND: In order to develop the production of sweet onions (Allium cepa L.) and onions with a high content of flavonols and fibre in Norway, it was necessary to evaluate available cultivars with respect to their content of selected chemical compounds. A field trial with 15 different cultivars was conducted at Landvik in southern Norway. Compounds that reflect onion pungency and sweetness (pyruvate, sugars) and parameters known to have a beneficial impact on health (fructo‐oligosaccharides (FOS), flavonols, antioxidant capacity) were analysed. RESULTS: The sweetest onions with respect to low content of pyruvate and high amount of fructose and glucose ranged in pyruvate content from 2.7 to 3.6 µmol mL^?1. These cultivars were juicy and contained low amounts of FOS and total flavonols. The most pungent onions contained the highest amounts of FOS among the cultivars: 4.53, 3.80 and 5.81 g per 100 g fresh weight (FW) respectively. They also had a high content of flavonols (86.6, 159.2 and 97.6 mg per 100 g FW) and high dry weight content (14.6, 13.5 and 15.6 g per 100 g). CONCLUSION: The sweetest onion cultivars were found to be ‘NUN 9746’, ‘Musica’, ‘Domenica Supersweet’, ‘Colossus’ and ‘Cronus’. The most pungent cultivars were ‘Powell Brown’ and ‘Tilbury’, which also contained the highest amounts of flavonols and gave the highest Trolox equivalent antioxidant capacity (TEAC) values among the 15 cultivars. Copyright © 2007 Society of Chemical Industry     

Implications of spatial and temporal changes in concentration of pyruvate and glucose in onion (Allium cepa L.) bulbs during controlled atmosphere storage

BACKGROUND: Pungency and perceived sweetness are important quality assurance parameters for onion producers; however, there is still a paucity of information describing the spatial changes within the bulb of some taste‐related compounds during storage. Accordingly, onion bulbs of cultivars (cvs.), SS1 (low pungency, low dry matter) and Renate (pungent, high dry matter) bulbs, were divided into 12 sections and both spatial and temporal variations of pyruvate and glucose were recorded during standard controlled atmosphere storage. RESULTS: Pyruvate within cv. SS1 bulbs reached 8.3 µmol g^?1 fresh weight (FW) from pre‐storage levels of less than 3.4 µmol g^?1 FW, whilst pyruvate changes in cv. Renate remained in the ‘pungent’ category, between 12 µmol g^?1 FW and 15 µmol g^?1 FW; thus having fewer implications for marketing and quality assurance. Glucose concentrations were significantly higher for both cvs. in the neck region as compared to basal tissue. Higher glucose levels were recorded in the core of the bulb than in outer scales of cv. Renate. The opposite was found for cv. SS1. There was an inverse correlation of ? 0.69 and ? 0.87 between glucose and pyruvate for cvs. SS1 and Renate, respectively. CONCLUSION: In order to measure overall bulb flavour, it is recommended that sampling procedures, particularly for routine pungency determination, be carried out on bulb quarters or wedges rather than equatorial sections. Copyright © 2009 Society of Chemical Industry     

Kinetics of the ozone gas reaction in popcorn kernels

The objectives of this work were to determine the saturation times for popcorn kernels exposed to different concentrations of ozone gas (O₃) in a constant flow; to study the kinetics of the ozone gas decomposition in the grain mass; and to ascertain the ozone treatment effect on grain quality. In order to promote saturation and to study the decomposition reaction kinetics, samples of popcorn kernels were exposed to ozone gas or atmospheric air (control) at a specific flow rate of 0.33 m³ min⁻¹ t⁻¹, and concentrations of 500, 2200, and 4500 μg L⁻¹. The popping expansion volume, water content and electrical conductivity of the ozonized popcorn kernel samples were considered to investigate the effect of ozone treatment on popcorn quality. The effect of ozone treatment on insect mortality was also evaluated. The grain masses treated at ozone concentrations of 500, 2200, and 4500 μg L⁻¹ reached the saturation condition after 10, 3.1, and 2.1 h, respectively. At all concentrations considered, the decomposition kinetics of the ozone gas when in contact with the saturated grain mass was best explained by a first-order model. The decomposition rate constants were equal to 0.13, 0.11, and 0.12 min⁻¹, for the concentrations of 500, 2200, and 4500 μg L⁻¹, respectively. At these ozone levels, the quality analyses of the popcorn grains did not reveal alterations that could compromise the product commercially. Nevertheless, the concentrations of 500, 2200, and 4500 μg L⁻¹ proved to be lethal to the insects at the exposure times corresponding to the saturation in each case.