Effect of polyols on flavor release during mastication of sugar-free confections

Abstract

Flavor is one of the most important attributes influencing food choice. In confectionery products, a major focus on product innovation involves developing more desirable flavor attributes for maximum impact and duration as well as providing healthier products. In addition to advances in flavor technology, the confectionery industry has moved towards products that are sugar-free by utilizing polyols (sugar alcohols) instead of traditional sugar ingredients, such as sucrose or glucose. Polyols, like sugar, provide sweetness to a confectionery product and can also impact the product performance in multiple ways such as the texture and the flavor release properties. Currently there is limited knowledge on how polyols alter flavor delivery and ultimately impedes product innovation. The overall objective of this thesis was to investigate the influence of polyols on delivery of flavor components, volatiles (aroma) and non-volatiles (taste), in confectionery products. As an initial study (presented in Chapter 3) a model confectionery product was formulated with different polyols: xylitol, mannitol or sorbitol that ranged in physical-chemical properties. Release of volatile and non-volatile flavor components was monitored close to the respective biological receptors of three trained panelists over a 12 min mastication period. Real-time release of volatile flavor compounds (aroma) were measured in exhaled breath by APCI-MS analysis, and non-volatile flavor compounds (taste, polyols and high intensity sweeteners, HIS: acesulfame K and aspartame) were monitored in expectorated saliva by LC/MS/MS analysis. In general, the rate of delivery of both aroma and taste components were inversely related to the water solubility of the polyol utilized. The flavor release profiles for both the aroma and HIS compounds were highest for the sample formulated with the least water-soluble polyol (mannitol) and lowest for sample with the most water-soluble polyol (sorbitol). Time-intensity sensory evaluation of these samples was also in agreement with the instrumental data supporting the observed chemical changes in flavor delivery resulted in changes in flavor perception. Based on the observation that water solubility of polyols influenced flavor delivery, we further hypothesized that surface area of the polyol material would also influence the flavor release profile. In chapter 4, the influence of polyol-type and particle size on the flavor release profile in a sugar-free confection was investigated in vivo. Four samples with an average particle size of 62 or 246μm (sorbitol) and 57 or 184μm (mannitol) were analyzed. Two trained panelists masticated the samples at a controlled chewing rate for 12 minutes period. APCI-MS analysis of the expired breath reported the samples formulated with mannitol, in general, had a higher aroma release profile than when formulated with sorbitol. LC/MS analysis of the expectorated saliva reported the HIS had a significantly higher release profile for the smaller polyol particle size samples; the release rate of polyol was not significantly changed by the particle size. Sensory time-intensity analysis of the sorbitol samples was also in agreement with the HIS delivery, the smaller particle size sorbitol gum was significantly higher in perceived sweetness intensity (compared to the larger particle sized sample). In summary, unique polyol-flavor interactions were reported to alter flavor delivery; the aroma compounds were mainly influenced by the polyol-type whereas the HIS by particle size (surface area). In the final research phase the mechanisms of flavor delivery in confections were further investigated by conducting a mass balance analysis of the volatile and non-volatile flavor compounds during a 12 min mastication of samples formulated with sorbitol of two particle sizes (Chapter 5). The mass and release rate of the volatile compounds (ethyl butyrate, benzaldehyde, menthol, menthone and limonene) were monitored in the exhaled breath, in the saliva and the sample bolus; whereas the non-volatiles compounds (sorbitol or mannitol, aspartame and acesulfame K) were monitored in the expectorated saliva and the sample bolus. In general, the percent recovery of the volatile compounds released during mastication was lower or was less quantifiable in comparison to the more polar non-volatile compounds. For the volatile compounds analyzed, the medium hydrophobicity region showed the lowest % recovery (< 10%) and suggested biological absorption was the main quantitative route of delivery in the oral cavity. The aroma release profile in the exhaled breath was reported not to be influenced by the compound concentration in the saliva or sample bolus during mastication but was suggested to be mainly controlled by residual levels of these compounds in the oral cavity or the lungs. Conversely, the percent recovery of the non-volatile compounds released from the samples during mastication was relatively high (> 90%). The release profile of both the polyol (sorbitol) and HIS compounds were reported not to be concentration dependent during the first 4 minutes of mastication. This suggested the polyol and HIS were physically entrapped in the sample matrix and the release mechanism was related to the surface exposure rate these compounds to the oral cavity during chewing (mechanical stress) for release to occur during mastication. In summary, we have reported novel mechanisms by which polyols influence the delivery of the aroma and taste compounds in sugar-free confectionery products as well as oral processing mechanisms that govern flavor delivery (absorption in the oral cavity). This information provides new knowledge for the food (and pharmaceutical) industry to tailor product quality.