The effect of inhomogeneous quinine and hydrocolloid distributions on the bitterness of model gels

This study investigated the effect of inhomogeneous distributions of quinine on bitterness intensity of gelatine–agar composite gels. It also investigated the effect of inhomogeneous distributions of the gel’s hydrocolloid constituents (the gelatine and agar) on the bitterness intensity of the quinine. Fifty-two screened subjects participated in four paired comparison tests comparing inhomogeneous designs of quinine (with a homogeneous hydrocolloid distribution) and inhomogeneous designs of the hydrocolloids (with a homogeneous quinine distribution), against a homogeneous control of identical overall quinine and hydrocolloid composition. Using the same gel designs, a mastication trial was undertaken where ten subjects were asked to chew each gel system until the point of swallowing, and eleven subjects participated in a time-intensity trial where bitterness intensity was monitored during mastication and after expectoration. Paired comparison tests showed that the inhomogeneous distribution of quinine increased bitterness intensity, while inhomogeneous distributions of the hydrocolloids did not. Mastication was not influenced by changes in the distribution of quinine or the hydrocolloids. Time intensity curves showed the gels having an inhomogeneous distribution of quinine had greater bitterness intensity throughout mastication, however no differences in bitterness intensity were observed between any gel designs in the latter stages of aftertaste measurements. Time intensity curves also showed a slight delay in time to maximum bitterness intensity for the gels with inhomogeneous distributions of hydrocolloids. Results suggest a homogeneous distribution of bitter compounds is the most suitable structure for minimising bitterness perception.     

Enhancement of sweetness intensity in gels by inhomogeneous distribution of sucrose

Model systems consisting of layers of mixed agar/gelatin gel were used to investigate the effect of the spatial distribution of sucrose on perceived sweetness intensity. 2-Alternative forced choice tests were performed with consumers to compare the sweetness of layered samples with an inhomogeneous distribution of sucrose to the sweetness of a reference sample with a homogeneous distribution. All samples had the same overall sucrose concentration (10%) and similar mechanical and rheological properties. Inhomogeneous samples that had large concentration gradients of sucrose between layers were perceived sweeter than the homogeneous reference. No differences in sweetness were observed between the reference and samples with small concentration gradients of sucrose. Additionally, the position of the layers containing sucrose did not affect sweetness. Results showed that an inhomogeneous distribution of sucrose can be used to reduce sucrose content by 20% without a decrease in sweetness intensity.     

Whey protein concentrate gels with different sucrose content: Instrumental texture measurements and sensory perception

Correlations between instrumental texture, sensory texture and sweetness perception were studied in whey protein concentrate (WPC) gels at different pH (4 and 7), sucrose (0–40%, w/w) and whey protein (10–20% w/w) content. The presence of sucrose modified the structure of WPC gels, mainly at pH 4, making the gel structure more homogeneous and with smaller pores. Sucrose also increased the solid behaviour of gels, their water holding capacity, hardness and adhesiveness. Sweetness perception decreased as protein concentration increased, and was higher in gels at pH 4 than in gels at pH 7. A good correlation was obtained between the instrumental and sensory attributes hardness, cohesiveness and elasticity.     

Inhomogeneous distribution of fat enhances the perception of fat-related sensory attributes in gelled foods

This study investigated the effect of the spatial distribution of fat on the perception of fat-related sensory attributes using a model system that consisted of layered agar/gelatin gels containing oil-in-water (O/W) emulsion droplets dispersed in the gel matrix. Four layers of gel varying in the amount of emulsion droplets were combined to prepare samples with homogeneous and inhomogeneous distributions of fat (emulsion droplets). The composition of the gels was optimized to obtain samples with comparable mechanical properties.     

Sweetening power of aspartame in hydrocolloids gels: Influence of texture

Equivalent sweetness of aspartame relative to two sucrose concentrations (10% and 20% w/w) were determined in water and in hydrocolloids gels. The influence of the texture of three hydrocolloids gelled systems—gellan gum, κ-carrageenan, and κ-carrageenan/locust bean gum (LBG)—at two gums concentrations (0.3% and 1.2% w/w) on the equivalent sweetness of aspartame were then studied. For the three gelled systems, the increase in hydrocolloid concentration produced a significant increase in the true rupture stress and in the deformability modulus values. For both κ-carrageenan and mixed gels the true rupture strain values increased when increasing hydrocolloid concentration while for gellan gels, decreased. For the same hydrocolloid concentrations the κ-carrageenan/LBG gels showed the largest strain at rupture and gellan gels the smallest (most brittle). For both soft (0.3% gum) and hard (1.2% gum) gellan gels and κ-carrageenan gels, the concentrations of aspartame needed to deliver a sweetness intensity equivalent to that of gels with 10% sucrose (0.079–0.087% w/w) were similar to those obtained for aqueous solutions (0.084% w/v). For hard κ-carrageenan/LBG gels the corresponding concentration of aspartame was slightly lower. For all gelled systems the concentrations of aspartame needed to deliver a sweetness intensity equivalent to that of gels with 20% sucrose were higher for soft gels than for hard gels.     

The breakdown properties of heat-set whey protein emulsion gels in the human mouth

Differently structured whey protein emulsion gels were formed by heating at different concentrations of NaCl. The formation of gels was monitored by oscillatory rheometry. The large deformation properties relevant to breakdown properties in the human mouth were measured by a uniaxial compression test and fracture wedge set test using a texture analyzer. A panel of 8 subjects was used to examine the in-mouth behaviours of gels including mastication parameters, degree of fragmentation and oil droplet release. The results showed that in general the gel hardness increased with increasing NaCl concentration. The gels containing 10/25 and 100/200 mM NaCl were characterized as being soft and hard, respectively. These soft and hard gels had different breakdown patterns in the mouth. On the other hand, sensory experiments showed the gel with 10 mM NaCl needed a significantly lower number of chewing cycles (19.4 ± 2.1) compared with gels with higher NaCl. The values of median size of particles in masticated gels containing 10, 25, 100 and 200 mM NaCl were about 4.00, 2.85, 1.05 and 0.95 mm, respectively, which suggested that higher hardness led to greater fragmentation in the human mouth. The fragmentation of the gel was highly correlated with functions of the mechanical properties. There was no obvious coalescence of the oil droplets during oral processing and only very few oil droplets were released from protein matrix during mastication.     

Influence of Texture on Taste: Insights Gained During Studies of Hardness, Juiciness, and Sweetness of Apple Fruit

Apple flesh can be considered as a living structure within which juice and tastants are encapsulated in individual cells. The breakdown of this structure and release of juice varies between hard and soft apples. We hypothesized that the texture of the fruit and the way it releases juice during chewing would therefore influence the perception of sweetness. Time‐intensity (TI) techniques were used by a trained panel to study the temporal changes in the intensity of “juiciness” and “sweetness” during consumption of apples that varied in mechanical hardness (measured by puncture test). All apple samples had a similar water content, but the pattern of juice release was markedly different. Juice was released into the mouth in a pattern of increasing and then deceasing intensity. The maximum intensity (Imax), duration of the stimulus (DUR), and area under the TI curve (AUC) were significantly higher for hard compared with soft apples. The impact of juice release on perception of sweetness was examined using apples in which the Imax and AUC for juiciness of soft apples were half the value of those for firm apples. There was no consistent difference in Imax, DUR, or AUC for sweet taste in these 2 sets of apples. We concluded that sufficient juice was released from soft and less juicy apples to ensure that sweetness perception was maximized. These results are discussed in relation to earlier studies that demonstrated that texture (thickening agents) suppresses flavor perception in solutions and juices.     

Sweetness and texture perceptions in structured gelatin gels with embedded sugar rich domains

Layered and homogeneous gelatin gels with controlled rheological properties were compared for their sensory characteristics, specifically sweetness, hardness, breakdown behaviour and frothing. All gels and layers had a gelatin/water concentration of 5%. The total sugar concentration was 9% in the layered samples and 0, 9, 15 or 22.5% in the homogeneous samples. These concentrations corresponded to the concentrations in the single layers.A seven-layered sample with different sugar concentrations in the layers gave a higher early sweetness intensity than a homogeneous gel with the same mean total sugar concentration. All layered gels were similar in hardness, breakdown behaviour and frothing; for the homogenous samples, sensory hardness was decreased in samples with much sugar. These gels also fell into smaller pieces than the sugarless sample. This study shows that it is possible by controlling the sugar distribution within a sample to produce sweeter gels while the sugar content is maintained.     

Time-intensity Measurement of Flavor Release from a Model Gel System: Effect of Gelling Agent Type and Concentration

Flavor release from cornstarch, gelatin or iota carrageenan gels flavored with benzaldehyde, d-limonene or ethyl butyrate was measured at three gel strengths (soft, medium, firm) by 20 trained judges using the time-intensity (TI) method. At comparable gel strengths, starch and gelatin displayed greater flavor release properties than carrageenan, i.e., mean values for perceived maximum intensity (Imax) and total duration (Tdur) of flavor were higher for starch and gelatin than for carrageenan across flavors. Firm gelatin and carrageenan gels released flavor with a lower Imax than soft or medium gels, but Imax and Tdur did not vary across starch gel strengths. Results indicate both texture (firmness) and gelling agent affect flavor release from a gel.     

Compression test of soft gellan gels using a soft machine equipped with a transparent artificial tongue

A soft machine system (texture analyzer equipped with an artificial tongue) was developed to analyze the occurrence of fractures in soft food gels compressed between the tongue and hard palate. Artificial tongues were newly designed with a modulus similar to that of a somewhat tense human tongue, using transparent urethane gels. A model of soft foods that are easy or difficult to crush with the tongue was prepared using gellan gums at different concentrations. A piece of gellan gum gel was uniaxially compressed on an artificial tongue with the flat probe of a texture analyzer. The food gel and artificial tongue were deformed, leading to the fracturing of food gels alone. During compression-induced fracture, the softer food gels exhibited a lower force, lower displacement, and lower true stress than the harder gels on all artificial tongues. The fracture probability of gellan gels was lower for the combination of harder food gels and softer artificial tongues, as softer materials can deform to a larger extent. Fracture displacement of food gels was increased as the modulus of the artificial tongue decreased; however, the fracture force did not differ significantly. These results suggest that an artificial tongue with elastic modulus values similar to those of the actual human tongue is suitable for determining the fracture behavior of foods during compression between the tongue and hard palate.     

The effect of modifying the distribution of sucralose and quinine on bitterness suppression in model gels

This study investigated the effect of simultaneously manipulating the spatial distribution of a sweet masking agent and bitter tastant within gelatine–agar gels on bitterness suppression, using sucralose and quinine. Sixty subjects participated in a series of paired comparison tests comparing different gel designs containing both sucralose and quinine, against a homogeneous control gel of identical overall sucralose (0.3 mM) and quinine content (0.3 mM). Twenty subjects also determined the bitterness reduction achieved in the homogeneous control gel by the addition of 0.3 mM sucralose to 0.3 mM quinine. Separating quinine and sucralose into different portions of the gel had no influence on bitterness suppression. Inhomogeneously distributing the quinine and sucralose into the same parts of the gel reduced the effectiveness of bitterness suppression. Inhomogeneously distributing the sucralose, while maintaining a homogeneous distribution of quinine, had no influence on bitterness suppression. Although an inhomogeneous distribution of sucralose increased sweetness perception and the addition of sucralose (0.3 mM) was found to substantially reduce bitterness in the homogeneous control, bitterness suppression was not enhanced when distributing the masking agent (sucralose) inhomogeneously.     

影响凝胶甜味的关键质构因素分析

为了确定影响凝胶甜味的关键质构因素,建立了具有不同质构特征的9种凝胶,采用描述性分析评价其甜味及质构特征,并通过扫描实际咀嚼过程中形成的凝胶碎片进行验证。结果表明,影响凝胶中甜味释放的关键质构因素是易碎性和凝聚性。凝胶碎片扫描结果显示,易碎性较强、凝聚性较弱的样品会形成更多的凝胶碎片和更大的凝胶总表面积,这可能是导致样品甜味更强的原因。此外,较低易碎性样品的甜味还受到润湿性的调控,而高易碎性样品则不受影响。高硬度和低弹性的样品会形成棱角更清晰的凝胶碎片,导致在吞咽前需要经过更多次数的咀嚼,生成更多的凝胶碎片,间接增强凝胶的甜味。     

On the Effect of Tastant Excluded Fillers on Sweetness and Saltiness of a Model Food

ABSTRACT: In this study, the effect on taste due to the addition of air bubbles to a water-based gel was investigated. The gel phase contained either sucrose to give a sweet taste or sodium chloride to give a salty taste. For the sweet gels, taste intensities were evaluated for samples with different volume fractions of the air bubbles (up to 40%, v/v) and different concentrations of the sucrose. For the salty gels, samples were evaluated at 40% volume fraction of air bubbles. It was found that a reduction of the sodium chloride or sucrose by the same weight percentage as the volume fraction of the air bubbles in the samples gave equal taste perception as the nontastant-reduced samples. Moreover, saltiness and sweetness perception were clearly enhanced at 40% volume fractions of air bubbles if the sodium chloride or sucrose was not reduced. Thus, the overall tastes of the samples appeared to depend mainly on the concentration levels of the salt or the sucrose in the aqueous phase irrespective of the volume fraction of the air bubbles. However, the air bubbles were found to change the texture and appearance of the samples. It has been demonstrated that the inclusion of air bubbles offers scope for the reduction of sodium chloride or sucrose in food products.     

Modulation of sweetness perception in confectionary applications

The development of sugar-reduced food products is a strategy to reduce the high sugar intake, which is a leading cause of global health concerns. Replacement and/or reduction of sucrose often leads to reduced sweetness perception with the consequence of decreased consumer acceptance. The aim of this work is to implement sensory modulation principles in a model confectionery system with the goal of enhancing sweetness perception. By using 3D-printing, confectionary samples were meso-structured by inhomogenous distribution of sucrose concentrations and assessed with a trained panel regarding sweetness. All samples were made up of a high and low sucrose phase and compared to a homogeneous reference sample. The overall sugar content was kept constant at 22.8% in all samples and sweetness perception was compared. A significant increase of sweetness perception by over 30% was found for samples consisting of a sweet outer shell and an inner less sweet core with a high sucrose gradient between the two phases. Whilst textural effects on sweetness perception could not be fully excluded, results can be seen as a strong indication that sweetness modulation by inhomogenious distribution has a potential to be applied directly in solid food products.     

Influence of texture on the temporal perception of sweetness of gelled systems

The aim of this work was to study how the texture of two hydrocolloid gelled systems with different mechanical properties – κ-carrageenan and gellan gum – sweetened with two sweeteners with different sweetening power – sucrose and aspartame – influence the temporal perception of sweetness using a time–intensity test. The results show that the different aspects of temporal perception of sweetness of hydrocolloid gels were related to their mechanical properties in different ways. Maximum sweetness intensity was closely related to the amount of deformation required to break the network and with its resistance to deformation. Meanwhile resistance to rupture was also an important factor influencing the variation in the rate of intensity decrease. The time needed to reach maximum sweetness intensity was only dependent on sweetener concentration.     

Influence of oat gum, guar gum and carboxymethyl cellulose on the perception of sweetness and flavour

The influence of three pseudoplastic hydrocolloids, oat gum, guar gum and carboxymethyl cellulose (CMC) on sensory perception of sweetness and flavour was studied in model systems at two viscosity levels. The sweeteners studied were sucrose, fructose and aspartame, the flavour substances ethyl caproate, a-pinene and cinnamic acid. Sweetness was best perceived from oat gum solutions and most weakly from guar gum solutions. The effect of the composition of the thickener on the perception of sweetness was greater than that of viscosity. Reduction of sweetness by hydrocolloids was weaker for aspartame than for fructose or sucrose. In the perception of flavours, both the total length of perception and the time-intensity pattern were more dependent on the model aroma substance than on the thickener. Possible explanations for the differences are discussed.     

Linking oral processing behavior to bolus properties and dynamic sensory perception of processed cheeses with bell pepper pieces

The addition of food particles to food matrices is a convenient approach that allows to steer oral behavior, sensory perception and satiation. The aim of this study was to determine the influence of physical-chemical properties of heterogenous foods on oral processing behavior, bolus properties and dynamic sensory perception. Bell pepper gel pieces varying in fracture stress and concentration were added to processed cream cheese matrices differing in texture. Addition of bell pepper gel pieces to processed cheeses increased consumption time, decreased eating rate and led to harder and less adhesive bolus with more saliva incorporated. Addition of bell pepper gel pieces to processed cheeses decreased dominance rate and duration of creaminess, smoothness, melting and dairy flavor and increased graininess and bell pepper flavor. Increasing fracture stress of bell pepper gel pieces from 100 to 300 kPa resulted in longer consumption time and lower eating rate. For hard/non-adhesive processed cheese matrices increasing gel pieces fracture stress lead to a boli with larger particles and more saliva. These changes were accompanied by decreased dominance perception of creaminess and bell pepper flavor and increased dominance of graininess. Increasing the concentration of bell pepper gel pieces from 15 to 30% did not affect oral behavior but led to the formation of harder and less adhesive bolus with larger particles and less saliva that were perceived with reduced dominance of creaminess, meltiness and dairy flavor while dominance of graininess and bell pepper flavor increased. Changing the texture of the cheese matrix from soft/adhesive to hard/non-adhesive decreased consumption time, increased eating rate, did not influence bolus properties and decreased dominance rate of creaminess, smoothness and melting sensations. Number of chews and total consumption time were positively correlated with saliva content of the bolus, number of bolus particles, bolus hardness, dominance of firmness, chewiness and graininess. We conclude that the modification of physical-chemical properties of processed cheeses and embedded bell pepper gel pieces can be a strategy to steer oral behavior and bolus properties which consequently determine dynamic sensory perception.     

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.