Effect of sucrose on the perceived flavor intensity of chewing gum.

The release of sucrose and menthone from chewing gum was measured in-mouth and in-nose, respectively, during eating. Swabs of saliva were taken from the tongue and analyzed using a rapid, direct liquid-mass spectrometry procedure. Menthone concentration in-nose was monitored on a breath-by-breath basis using direct gas phase atmospheric pressure chemical ionization-mass spectrometry. Simultaneously with the volatile release, trained panelists followed the change in mint flavor by time-intensity (TI) analysis. Two types of commercial chewing gum were analyzed. Both showed that the panelists perception of mint flavor followed sucrose release rather than menthone release. The temporal analysis of the chemical stimuli, with simultaneous TI analysis, provided unequivocal evidence of the perceptual interaction between nonvolatile and volatile flavor compounds from chewing gum.     

Flavor perception and aroma release from model dairy desserts

Six model dairy desserts, with three different textures and two sucrose levels, were equally flavored with a blend of four aroma compounds [ethyl pentanoate, amyl acetate, hexanal, and (E)-2-hexenal] and evaluated by a seven person panel in order to study whether the sensory perception of the flavor and the aroma release during eating varied with the textural characteristics or the sweetness intensity of the desserts. The sensory perception was recorded by the time intensity (TI) method, while the in vivo aroma release was simultaneously measured by the MS-nose. Considering the panel as a whole, averaged flavor intensity increased with sucrose level and varied with the texture of the desserts. Depending on the aroma compound, the averaged profile of in vivo aroma release varied, but for each aroma compound, averaged aroma release showed no difference with the sucrose level and little difference with the texture of the desserts. Perceptual sweetness-aroma interactions were the main factors influencing perception whatever the texture of the desserts.     

Mechanisms of flavor release in chewing gum: cinnamaldehyde

Recently we reported that the release profile of cinnamaldehyde from a sugar-free chewing gum was correlated to the release of the sugar alcohol phase or was not in agreement with the log P model. The objective of this study was therefore to investigate mechanisms of cinnamaldehyde release from a sugar-free chewing gum; p-cresol (similar log P value) was also analyzed for comparison. Breath analysis of the chewing gum samples over an 8 min consumption period reported that the maximum concentration of cinnamaldehyde was 2- to 3-fold higher during the initial phase of mastication in comparison to the later phase, whereas the concentration of p-cresol was relatively constant over these two time periods. By contrast the release profile of cinnamaldehyde from a flavored gum base (no sugar alcohol phase) was constant over the 8 min consumption period and similar to the release of cresol from the flavored gum base. On the basis of tandem mass spectrometry, cinnamaldehyde was reported to react with sorbitol and generate hemiacetal reaction products that were not stable under slight alkaline conditions; it was suggested to revert back to free cinnamaldehyde and sugar alcohol in the oral cavity. The increased polarity of these transient cinnamaldehyde-sorbitol hemiacetal reaction products would result in a more rapid release rate of cinnamaldehyde than would be typically predicted based on the affinity of cinnamaldehyde for the gum base.     

In vivo aroma release of milk gels of different hardnesses: inter-individual differences and their consequences on aroma perception

The effect of textural modifications of solid milk gels on in vivo aroma release and aroma perception was investigated with a panel of 14 subjects. Great inter-individual differences were observed on aroma-release data, and the consequences of these differences on aroma perception were studied. From a hierarchical cluster analysis performed with several parameters extracted from release curves, the subjects were gathered into two groups, and a specific aroma-release profile was identified for each one. Then, by using a sensory profile, we showed that the intensity of the aroma perception was dependent on the release profile presented by the panelist. Second, we observed that, during the chewing phase, the aroma was perceived as more intense for the firmer gel and for panelists for whom the aroma release begins during the chewing of the product.     

The role of fat in flavor perception: effect of partition and viscosity in model emulsions

Decreasing the fat content of a food, while maintaining the same aroma content, changes both aroma release (due to partition effects) and the viscosity of the food. To understand the relative contribution of these two factors on flavor perception, a series of flavored emulsions were prepared to control aroma release and viscosity using different aroma, oil, and hydroxypropyl methyl cellulose (HPMC) contents. Samples were formulated to deliver the same aroma-release in vitro and in vivo, and their viscosity was measured using the Kokini oral shear stress parameter. Despite the in vivo aroma release being constant, there were perceptual differences between the samples, and the flavor intensity decreased as in-mouth viscosity increased. For these iso release samples, the Kokini oral shear stress parameter correlated well with the decrease in perception, suggesting that there may be a viscosity stimulus or that the viscosity affects release of tastant and hinders aroma-taste interactions.     

Volatile flavor analysis and sensory evaluation of custard desserts varying in type and concentration of carboxymethyl cellulose

The influence of type and concentration of carboxymethyl cellulose (CMC) on flavor and textural properties of custard desserts was examined. A synthetic strawberry flavor mixture was used to flavor the custards; it comprised 15 volatile flavor compounds. The viscosity of the custards was determined using rheometric measurements. Static headspace gas chromatography and in-nose proton transfer reaction-mass spectrometry analyses were conducted to determine the custards' volatile flavor properties. Perceived odor, flavor, and textural properties were assessed in sensory analysis experiments using magnitude estimation against a fixed modulus. Both type and concentration of CMC altered the viscosity of the custards. Softer custards had higher static headspace flavor concentrations. On the contrary, firmer custards demonstrated higher in-nose flavor concentrations. In sensory analysis, firmer custards showed higher thickness and lower sweetness intensities than their low-viscosity counterparts. The thickness perception corresponded to the viscosity of the custards. Removal of sucrose from the custards affected sweetness intensity only and not the intensity of other attributes. Therefore, the influence of the viscosity of the custards on the release of sweet-tasting components is held responsible for the effect on perceived sweetness intensity. Odor intensities were generally higher for the low-viscosity custard, whereas fruity flavor intensities were higher for the firmer custards. Odor intensities correlated with static headspace concentrations and flavor intensities related reasonably well with in-nose concentrations. Opening and closing of the nasal cavity is regarded as an important factor determining the discrepancy between static and in-nose measurements.     

Flavor release and perception in hard candy: influence of flavor compound-flavor solvent interactions

The release kinetics of l-menthol dissolved in propylene glycol (PG), Miglyol, or 1,8-cineole (two common odorless flavor solvents differing in polarity and a hydrophobic flavor compound) were monitored from a model aqueous system via atmospheric pressure chemical ionization mass spectrometry (APCI-MS). Breath analysis was also conducted via APCI-MS to monitor release of l-menthol from hard candy that used PG and Miglyol for l-menthol incorporation. The quantities of l-menthol released when dissolved in PG or Miglyol from the model aqueous system were found to be similar and overall significantly greater in comparison to when dissolved in 1,8-cineole. Analogous results were reported by the breath analysis of hard candy. The release kinetics of l-menthol from PG or Miglyol versus from 1,8-cineole were notably more rapid and higher in quantity. Results from the sensory time-intensity study also indicated that there was no perceived difference in the overall cooling intensity between the two flavor solvent delivery systems (PG and Miglyol).     

In vivo flavor release from gelatin-sucrose gels containing droplets of flavor compounds

Gelatin-sucrose gels containing the same amount of flavor compounds present as either suspended droplets or homogenously distributed in the gel (dissolved) were eaten, and the in vivo flavor release was studied using atmospheric pressure chemical ionization-mass spectrometry. The maximum intensity of release was higher from all droplet-containing samples as compared with the dissolved sample (by a factor of 4-2500-fold). When the flavor was dispersed as a greater number of smaller droplets rather than one 1 microL droplet, the intensity of in vivo release was slightly lower. The release of 16 of the flavor compounds varied in their Log P (range 0.26-4.83) and vapor pressure (Log vapor pressure ranged from -1.09 to 1.99). The differences in release for flavors present as either droplets or dissolved in the gel matrix were strongly influenced by both of these factors. This suggested a different mechanism for flavor release from droplets as compared to the classical partition mechanism established for dissolved flavors.     

Sweetener/sweetness-induced changes in flavor perception and flavor release of fruity and green character in beverages

Green leaf volatile (GLV) mixtures, commercial orange flavors, and commercial strawberry flavors were applied to beverage bases in which concentrations of citric acid as well as a sweetener (sucrose or aspartame/acesulfame-K) were varied. Sensory profiling showed that flavor-specific fruity character increased as perceptible sweetness increased, independent of whether the sweetness resulted from sucrose (a change from 9 to 12 Brix) or aspartame/acesulfame-K (a change from 0.2 to 0.4 Brix). Sweetness was affected only by the tastants in the base and not by the flavors, although flavor-specific interactions between sweetener type and sweetener level occurred. Flavor release from the sucrose bases was compared to flavor release from bases containing aspartame/acesulfame-K by static headspace measurements and by MS-Nose measurements using an artificial throat. These measurements showed greater flavor volatility from bases having low Brix (fewer soluble solids). This negative Brix effect was also evident in the sensory data for perception of some GLV green notes. The headspace data could not support a positive Brix effect, the typical salting out, which would correspond to the observed perceptual enhancement of fruity notes.     

Release and perception of ethyl butanoate during and after consumption of whey protein gels: relation between textural and physiological parameters

The influence of gel texture on parameters such as positioning of food material in the oral cavity during mastication, and salivation, and their influence on aroma release in vivo was studied. Retronasal perception was followed by means of time-resolved sensory evaluation, while volatile release patterns were observed by means of PTR-MS. A clear correlation was found between individual-specific consumption patterns and the respective sensory perception. Also, gel texture could be clearly correlated with respective physicochemical release patterns in vivo and to the corresponding retronasal aroma perception.     

Use of fiber interface direct mass spectrometry for the determination of volatile flavor release from model food systems.

Described in this paper is a fiber interface direct headspace mass spectrometric system for the real-time measurement of flavor release. The system was optimized for the detection of the garlic aroma volatile, diallyl disulfide, from water. Parameters investigated included interface temperature, flow rate through the fiber, flow rate through the sample vessel, and sample stir rate. The delay time for detection of sample after introduction into the sample vessel was determined as 43 s. The system proved to be reliable and robust with no loss in sensitivity or contamination of the mass spectrometer over a 6 month period. The technique was applied to a homologous series of aliphatic alcohols from C(2) to C(7). Results showed that as polarity decreased with increasing chain length the release of volatile into the headspace was faster and gave a higher maximum intensity. Release of the garlic aroma volatile from different commercial mayonnaise products clearly showed a decrease in the release of diallyl disulfide as fat content increased. These results demonstrate the potential of using this technique as a tool for understanding the complex interactions that occur between flavor compounds and the bulk food matrix.     

The influence of gel strength on aroma release from pectin gels in a model mouth and in vivo, monitored with proton-transfer-reaction mass spectrometry

The course of events from taking a food into the mouth to the perception of the food's flavor involves many steps, from dilution with saliva, mastication, and transportation of the compounds to the olfactory epithelium to transformation into signals that go to the brain. In addition, there are also the effects of the food's structure and properties. In this study, a proton-transfer-reaction mass spectrometer (PTR-MS) was used to investigate how four pectin-containing systems with different structures and strengths affected the release of aroma compounds in a model mouth and in the nose of an assessor. Both the model mouth and the in-nose measurements showed that the strength and structure of pectin-containing systems are important with regard to the quantity of aroma compounds that are released. Mastication and saliva were also shown to have a large influence on how much of the aroma compound is released from the mouth to the nose.     

Altering the fat content affects flavor release in a model yogurt system.

Flavored yogurts differing in fat content were eaten, and the release of flavor volatiles was measured by monitoring the volatile composition of air from the nose in real time by atmospheric pressure ionization mass spectrometry. Low-fat yogurts (0.2%) were found to release volatiles more quickly and at higher intensity but with less persistence than yogurts containing fat at 3.5 and 10% fat. Yogurts with increasing fat content had higher viscosity and lower relative particle size. Lipophilic compounds were more affected by fat for maximum volatile intensity, but not time-to-maximum intensity or persistence. Sensory assessment of the yogurts found significant differences in intensity and speed of onset of flavor, but not overall length of perception.     

Flavor release and perception in hard candy: influence of flavor compound-compound interactions

The influence of flavor compound-compound interactions on flavor release properties and flavor perception in hard candy was investigated. Hard candies made with two different modes of binary flavor delivery, (1) L-menthol and 1,8-cineole added as a mixture and (2) L-menthol and 1,8-cineole added separate from one another, were analyzed via breath analysis and sensory time-intensity testing. Single-flavor candy containing only L-menthol or 1,8-cineole was also investigated via breath analysis for comparison. The release rates of both L-menthol and 1,8-cineole in the breath were more rapid and at a higher concentration when the compounds were added to hard candy separate from one another in comparison to their addition as a mixture (conventional protocol). Additionally, the time-intensity study indicated a significantly increased flavor intensity (measured as overall cooling) for hard candy made with separate addition of these flavor compounds. In conclusion, the flavor properties of hard candy can be controlled, at least in part, by flavor compound-compound interactions and may be altered by the method of flavor delivery.     

Reduction of stale flavor development in low-heat skim milk powder via epicatechin addition

The influence of epicatechin (EC) on off-flavor development in low-heat skim milk powder samples during processing and storage was investigated. Milk powder samples were prepared from a concentrated skim milk (control) plus a concentrated skim milk with EC (treatment). Volatile extracts of the powders were analyzed by aroma extract dilution analysis (AEDA) at 0 days and after 17 months of storage in conjunction with sensory analysis of the flavor attributes. The treatment milk powders with EC added prior to drying reported a reduction in the formation of three main compounds, 4-hydroxy-2,5-dimethyl-3-(2H)-furanone, o-aminoacetophenone, and furfural, by 8-, 4-, and 4-fold for the 0 day old samples, while for the 17 month aged samples o-aminoacetophenone was the major compound reduced in formation by 8-fold, respectively, based on the flavor dilution factors reported. The sensory evaluations indicated that the treatment milk powders for 0 day old and 17 month aged samples were statistically lower (alpha = 0.05) in stale flavor intensity in comparison to the respective control samples, while no differences were noted in bitterness intensity.     

Effect of xanthan on flavor release from thickened viscous food model systems

The influence of xanthan concentration (0, 0.02, 0.1, 0.4, and 0.8% w/w) and bulk viscosity on the release of 20 aroma compounds of different chemical classes (5 aldehydes, 4 esters, 5 ketones, 3 alcohols, and 3 terpenes) was evaluated in xanthan-thickened food model systems having different viscosities. Interactions between flavor compounds and xanthan were assessed by measuring air-liquid partition coefficients, K, of aroma compounds in pure water and in the xanthan solutions by static headspace gas chromatography. Mass transfer of aroma compounds was estimated by dynamic headspace gas chromatography. Notably, limonene and some of the esters and aldehydes exhibited decreased K values in the presence of xanthan, indicating that the release of these volatile aroma compounds was reduced due to interaction with the xanthan matrix. The degree of interaction depended on the physicochemical characteristics of the aroma compounds. A similar tendency was observed at nonequilibrium with the decreases in release rates being most pronounced for limonene, followed by the esters and aldehydes, with no effect for ketones and an apparent "salting out" effect for alcohols. The reduction in flavor release by xanthan was thus dependent on the physicochemical properties of the aroma compounds and was apparently a result of the aroma-xanthan interactions and not influenced by the viscosity of the system itself.     

滋味物质在不同交联度鱼糜凝胶中的释放动力学分析

为探讨滋味物质在不同交联度鱼糜凝胶中的释放规律并揭示其释放机制,该研究以氯化钠、蔗糖和谷氨酸钠分别为鱼糜凝胶咸味、甜味和鲜味的代表滋味物质,通过感官评价、释放动力学模型拟合和模拟咀嚼释放等方法,分析滋味物质在不同交联度鱼糜凝胶中的释放规律。结果表明,随着交联度的增加,人体对咸味的感知逐渐降低而对鲜味的感知逐渐增强,并当交联度大于42.2%时,咀嚼破碎显著提高了鱼糜凝胶咸味和鲜味的感知（P<0.01）。氯化钠和蔗糖的释放动力学曲线符合准一级动力学模型,而谷氨酸钠的释放则符合准二级动力学模型。随着交联度的增加,鱼糜凝胶在模拟咀嚼过程中氯化钠和蔗糖的释放量先降后升,分别在交联度为42.2%和51.5%时取得最小值（4.54和3.38 mg/g）;而谷氨酸钠的咀嚼释放量则逐渐增加。相关性分析结果表明,氯化钠和蔗糖在鱼糜凝胶中的释放主要与网络结构和化学作用力相关,谷氨酸钠的释放主要与凝胶质地、凝胶持水性和化学作用力相关。综上,滋味物质在鱼糜凝胶中的释放行为受滋味物质种类、凝胶质地以及凝胶与滋味物质的相互作用等多方面的影响,且凝胶在咀嚼过程中较高的破碎程度增强了滋味物质的释放与感知。