Chewing differences in consumers affect the digestion and colonic fermentation outcomes: In vitro studies

It is important to understand variability in consumer chewing behavior for designing food products that deliver desired functionalities for target consumer segments. In this study, we selected 29 participants, representing...

Subthreshold chemesthetic stimulation can enhance flavor lastingness of a soft chewable candy

In addition to taste and aroma components of a flavor, FEMA GRAS approved chemesthetic flavor ingredients deliver a trigeminal experience or chemesthetic effect and provide a third dimension to overall flavor experience. In this study, we explored the impact of chemesthetic stimulation on dynamic flavor perception, acceptability and salivation, with two base flavors (mint, watermelon), using a soft chewable candy as a model food. Each base flavor was augmented with three increasing levels of a mixture of chemesthetic flavor ingredients, which provided a cooling sensation; subthreshold, detection threshold, and supra-threshold levels. Thirty-six panelists were asked to rate the perceived flavor intensity of each sample during eating and after swallowing using time intensity analysis. Lastingness after swallowing was measured as the time for the flavor intensity to drop below 25% of the maximum intensity perceived during chewing. Compared with the control, the addition of chemesthetic flavor ingredients increased the perceived flavor intensity during chewing and the flavor lastingness after swallowing for both mint and watermelon flavor. These effects started from the addition of subthreshold concentration of chemesthetic flavor ingredients and further increased with increasing the concentration of chemesthetic flavor ingredients added. By adding the subthreshold concentration of chemesthetic flavor ingredients, the flavor lastingness was increased by 32% for mint flavor and 22% for watermelon flavor. The acceptability of these weak-flavored soft chewable candy test samples was significantly increased towards 'just right' with increasing concentrations of chemesthetic flavor ingredients, even at subthreshold level. However, chew time and saliva flow rate were not affected by the addition of chemesthetic flavor ingredients. The increased flavor lastingness by the addition of chemesthetic flavor ingredients could therefore be explained by perceptual interaction between chemesthesis and flavor perception.

Dynamic flavor perception of encapsulated flavors in a soft chewable matrix

Encapsulation is commonly used to protect flavor compounds against adverse environmental and processing conditions or to provide controlled release in processed foods. Flavor compounds are released during eating and the release rate depends on food breakdown dynamics in the mouth. Two sequential studies were designed to explore the flavor perception of the same flavor in different encapsulation systems. The studies were focused on the interactions between encapsulation technology, particle size and breakdown processes in the mouth. A peppermint flavor was used as a model flavor and encapsulated with different technologies (spray drying, melt extrusion and fluidized bed drying). The encapsulated flavors and a selected combination were incorporated into a soft chewable candy, keeping the total flavor concentration the same for each sample. The chewable candy samples were presented to naïve panelists (n > 30) for the following two evaluations; (1) comparison of overall flavor perception with a 2-alternative forced choice test; and (2) dynamic evaluation of perceived flavor intensity over time during eating and after swallowing using time intensity. The results showed that the overall and dynamic flavor perceptions are greatly affected by the encapsulation technologies and particle sizes, and can be modulated by combining flavor particles produced by different encapsulation technologies depending on the application and desired flavor profile. The results also showed a large perceived flavor intensity variation between panelists, resembling variation among consumers. In an effort to better understand the relationship between the oral processing patterns and flavor perception, we used the JBMB® typing tool which gives four "Mouth Behavior" groups ("Chewers", "Crunchers", "Smooshers" and "Suckers") and explored to determine whether they would account for the variation. Compared with "Chewers" and "Crunchers", "Smooshers" tended to have a slower increase of flavor intensity during eating and a more gradual drop after swallowing. However, this needs to be confirmed with larger numbers of consumers (including suckers who were excluded in this study because they were not sufficient in numbers) and samples with a longer chew time.

Comparison of physical chewing measures to consumer typed Mouth Behavior

The purpose of this study was to investigate the hypotheses that when presented with foods that could be chewed in different ways, (1) are participants jaw movements and chewing sequence measures correlated with Mouth Behavior (MB) group, as measured by the JBMB typing tool? (2) can MB group membership can be predicted from jaw movement and chewing sequence measures? One hundred subjects (69 female and 31 male, mean age 27 ± 7.7 years) were given four different foods (Mentos, Walkers, Cheetos Puffs, Twix) and video recordings of their jaw movements made. Twenty-nine parameters were calculated on each chewing sequence with 27 also calculated for the first half and second half of chewing sequence. Subjects were assigned to a MB group using the JBMB typing tool which gives four MB groups ("Chewers," "Crunchers," "Smooshers," and "Suckers"). The differences between individual chewing parameters and MB group were assessed with analysis of variance which showed only small differences in average chewing parameters between the MB groups. By using discriminant analysis, it was possible to partially discriminate between MB groups based on changes in their chewing parameters between foods with different material properties and stages of the chewing. A 19-variable model correctly predicted 68% of the subjects' membership of a MB group. This partially confirms our first hypothesis that when presented with foods that could be chewed in different ways participants will use a chewing sequence and jaw movements that correlate with their MB as measured by the JBMB typing tool.

PRACTICAL APPLICATIONS

The way consumers chew their food has an impact on their texture perception of that food. While there is a wide range of chewing behaviors between consumers, they can be grouped into broad categories to better target both product design and product testing by sensory panel. In this study, consumers who were grouped on their texture preference (MB group) had jaw movements, when chewing a range of foods, which partially reflected group membership. Therefore, while MB group membership could not be predicted from jaw movement measurements, there were similarities in jaw movements within the members of the groups. A better understanding of how jaw movement during chewing relates to consumer sensory perception would aid in new solid product design with controlled textural attributes.

Lubrication of chocolate during oral processing

The structure of chocolate is drastically transformed during oral processing from a composite solid to an oil/water fluid emulsion. Using two commercial dark chocolates varying in cocoa solids content, this study develops a method to identify the factors that govern lubrication in molten chocolate and saliva's contribution to lubrication following oral processing. In addition to chocolate and its individual components, simulated boluses (molten chocolate and phosphate buffered saline), in vitro boluses (molten chocolate and whole human saliva) and ex vivo boluses (chocolate expectorated after chewing till the point of swallow) were tested. The results reveal that the lubrication of molten chocolate is strongly influenced by the presence of solid sugar particles and cocoa solids. The entrainment of particles into the contact zone between the interacting surfaces reduces friction such that the maximum friction coefficient measured for chocolate boluses is much lower than those for single-phase Newtonian fluids. The addition of whole human saliva or a substitute aqueous phase (PBS) to molten chocolate dissolves sugar and decreases the viscosity of molten chocolate so that thinner films are achieved. However, saliva is more lubricating than PBS, which results in lower friction coefficients for chocolate-saliva mixtures when compared to chocolate-PBS mixtures. A comparison of ex vivo and in vitro boluses also suggests that the quantity of saliva added and uniformity of mixing during oral processing affect bolus structure, which leads to differences in measured friction. It is hypothesized that inhomogeneous mixing in the mouth introduces large air bubbles and regions of non-emulsified fat into the ex vivo boluses, which enhance wetting and lubrication.

Altering the rate of glucose release from starch-based foods by spray-drying with an extract from barley

BACKGROUND

Health outcomes associated with sustained elevated blood glucose may be better managed by limiting glucose availability for uptake. Glucose release from consumed starch may be altered using various methods, but many are not suitable for high-carbohydrate foods. This study describes an approach to protect starch granules, while generally maintaining their physical characteristics, with an extract from barley using spray-drying.

RESULTS

The use of the extract resulted in the coating of the starch granules with a film-like material composed of β-glucans and proteins. This coincided with a reduction in starch digestion and a significant increase in the indigestible (resistant) starch component. Substitution of the starch component in a model snack bar by the coated starch was also associated with lowering starch digestion in the bar.

CONCLUSION

The barley extract provides a physical barrier that may limit the exposure of starch to the digestive enzymes and water, with a consequent reduction in starch digestion and the rate of glucose release. It is possible, therefore, to produce wheat starch with lower digestibility and glucose release rate that may be used as a healthier substitute in high-carbohydrate foods by coating the granules with polymers extracted from barley cereals through spray-drying.

A device for the collection of submandibular saliva

The objective of this study was to describe the construction of a non-invasive device for the collection of submandibular saliva. Preliminary tests were carried out on saliva collected from a single donor in order to determine whether the rheological properties of submandibular saliva collected using the device were comparable to whole saliva collected using the expectoration (or 'spit') method. The device collected a lower quantity of saliva than that collected using the expectoration method. Stimulated saliva collected using the device had a pH close to that of unstimulated saliva because the sealed collection unit in the device minimised contamination. Saliva exhibited shear-thinning behaviour regardless of the method of collection, although that collected using the device was more viscous. The viscoelasticity of saliva collected using the two methods was different, probably as a result of differences in composition. This difference was greater with stimulated saliva. Despite the discrepancies between whole saliva and submandibular saliva, the device provides a non-invasive method for the collection of high-quality saliva over extended periods.

Modifying glucose release from high carbohydrate foods with natural polymers extracted from cereals

BACKGROUND

Sustained elevated blood glucose and insulin levels are linked to many health problems that may be prevented or better managed by controlling glucose availability for uptake. Glucose release from consumed starch may be altered by the processing conditions, particle size and structural features of the food, and by the addition of dietary fibres. Many approaches to lower glucose release are not suitable for all high carbohydrate foods, especially bakery products. Methods to modulate the starch digestion without compromising product quality are required. This study describes an approach to protect the granules and alter the particle size of the starch component using an extract from barley (BE). Wheat starch was suspended in the BE at different ratios and cast dried, milled to 2-3 mm particles, or finely ground to produce different particle sizes.

RESULTS

The BE treatments resulted in the formation of clusters of starch granules embedded in a matrix of fibres and protein. The rate of in vitro starch digestion was decreased, and further reduction occurred when the particle size of the starch material increased.

CONCLUSION

The extract provided a physical barrier that limited the starch exposure to the digestion enzymes and water that led to reduction in starch digestion and the release of glucose.