In-mouth Release Research Articles

Development of a New Approach to Estimate the In-mouth Release Characteristics of Odorants in Drinks

Development of a New Approach to Estimate the In-mouth Release Characteristics of Odorants in Drinks

Effect of sugar and acid composition, aroma release, and assessment conditions on aroma enhancement by taste in model wines

ContextWhen congruent taste and retronasal aroma are perceived simultaneously, aroma can be enhanced by taste. Different explanations have been proposed: (i) physico-chemical interactions between tastants and aroma compounds, inducing a change of the aroma stimulus before it reaches the receptors, (ii) a contextual bias during sensory tests (dumping), when at least one relevant attribute is not proposed to the panelists to assess a product, (iii) a misunderstanding of the conceptual difference between aroma and taste, or (iv) a perceptual incapability of panelists to distinguish between two congruent percepts. This study was undertaken to better understand aroma enhancement by taste in model wines containing different sugar and acid concentrations but the same volatile composition. MethodWe used a twofold approach:(i) model wine retronasal aroma intensity was assessed twice by trained panelists. During the first session, panelists only assessed aroma intensity. During the second session, taste intensity was assessed before aroma intensity, to reduce dumping effects.(ii) in-mouth release of volatile compounds was measured by nosespace analysis with the same panelists. ResultsAcid concentration influenced aroma compounds release, but its effect on perceived aroma intensity was not clear. Increasing sugar concentration delayed ethyl octanoate (EO) release after swallowing. When taste was not assessed, perceived aroma intensity was not explained by aroma compounds release, but it increased with sugar concentration, probably because of a dumping effect. When taste was assessed, aroma intensity also depended on sugar concentration, but it was significantly correlated to the time of release of EO. Our hypothesis is that when taste declined, late aroma was more easily individualized, and thus assessed with a higher intensity. This entails that panelists focused on aroma to individualize it from taste. We concluded that trained panelists understand the conceptual difference between taste and aroma, but are not completely able to distinguish congruent and simultaneous taste and aroma percepts.

Effect of marbling on volatile generation, oral breakdown and in mouth flavor release of grilled beef

While the positive effect of intramuscular fat (IMF) on beef tenderness is well-established, its role in flavor generation and flavor release is less defined. To increase understanding, real-time volatile generation was monitored during grilling of beefsteaks (grass and grain-fed Angus and grass-fed Wagyu) with different amounts of IMF by proton transfer reaction mass spectrometry. Volatile concentration increased significantly (p<0.001) when the IMF was >~10%, but did not differ (p>0.05) at lower IMF levels (5.2–10.2%). In vivo release of volatiles during consumption of grilled steaks was also measured using human subjects. Pre- and postswallow volatile release profiles varied according to marbling level and volatile fat solubility. In-mouth release of key hydrophilic volatiles was significantly greater (p<0.05) in high IMF grilled beef, consistent with more intense sensory flavor. Faster oral breakdown and higher peak saliva concentrations of non-volatile flavor compounds in high IMF grilled beef were consistent with higher tenderness and more intense flavor perception.

Aroma Precursors in Grapes and Wine: Flavor Release during Wine Production and Consumption.

Pioneering investigations into precursors of fruity and floral flavors established the importance of terpenoid and C13-norisoprenoid glycosides to the flavor of aromatic wines. Nowadays flavor precursors in grapes and wine are known to be structurally diverse, encompassing glycosides, amino acid conjugates, odorless volatiles, hydroxycinnamic acids, and many others. Flavor precursors mainly originate in the grape berry but also from oak or other materials involved in winemaking. Flavors are released from precursors during crushing and subsequent production steps by enzymatic and nonenzymatic transformations, via microbial glycosidases, esterases, C-S lyases, and decarboxylases, and through acid-catalyzed hydrolysis and chemical rearrangements. Flavors can also be liberated from glycosides and amino acid conjugates by oral microbiota. Hence, it is increasingly likely that flavor precursors contribute to retronasal aroma formation through in-mouth release during consumption, prompting a shift in focus from identifying aroma precursors in grapes to understanding aroma precursors present in bottled wine.

Determination of the Importance of In-Mouth Release of Volatile Phenol Glycoconjugates to the Flavor of Smoke-Tainted Wines

The volatile phenols guaiacol, 4-methylguaiacol, syringol, 4-methylsyringol, o-, m-, and p-cresol, as well as their glycoconjugates, have previously been shown to be present in elevated concentrations in smoke-tainted wine. Sensory descriptive analysis experiments, with addition of free volatile phenols in combination with their glycosidically bound forms, were used to mimic smoke taint in red wines. The addition of volatile phenols together with glycoconjugates gave the strongest off-flavor. The hydrolysis of glycosidically bound flavor compounds in-mouth was further investigated by in vitro and in vivo experiments. The results indicate that enzymes present in human saliva are able to release the volatile aglycones from their glycoconjugates even under low pH and elevated ethanol conditions, confirming that in-mouth breakdown of monosaccharide and disaccharide glycosides is an important mechanism for smoke flavor from smoke affected wines, and that this mechanism may play an important general role in the flavor and aftertaste of wine.

Impact of crema on the aroma release and the in-mouth sensory perception of espresso coffee

A set of six espresso coffees with different foam characteristics and similar above cup and in-mouth flavour sensory profiles was produced by combination of two varying parameters, the extraction pressure and the filtration of the coffee beverage. The coffees were subsequently evaluated in a comparative manner by a set of analytical (headspace, nose-space) and sensory (Temporal Dominance of Sensations) techniques. The presence of espresso crema in its standard quantity was demonstrated to be associated with the optimum release of pleasant high volatiles, both in the above cup headspace and in-mouth. On the other hand, the TDS study demonstrated that increasing amount of crema was associated with increasing roasted dominance along coffee consumption. Furthermore, a parallel was established between the roasted sensory dominance and the dominant release of 2-methylfuran in the nose-space. This was, however, an indirect link as 2-methylfuran was indeed a chemical marker of roasting but does not contribute to the roasted aroma. Lowering the standard amount of crema by filtration clearly decreased the release of pleasant high volatiles and the in-mouth roasted sensory dominance. On the other hand, increasing the usual crema volume by increasing the extraction pressure did not bring any added value concerning the above cup and in-mouth release of pleasant high volatiles.

New Factor Characterizing the In-Mouth Release of Odorants (Volatile Thiols): Compositional Changes in Odorants Exhaled from the Human Nose during Drinking

The aim of this research was to investigate the relationship between the odorants in the model drink and the odorants reaching the olfactory epithelium using the Retronasal Flavor Impression Screening System (R-FISS). By application of the R-FISS to the odorants in the model drink, it was found that a methylthio ether [1-methoxy-3-methyl-3-(methylthio)butane] was detected with the original volatile thiol (4-methoxy-2-methyl-2-mercaptobutane) in the air exhaled through the nostrils via the nasal cavity after the model drink (including the original thiol) had been swallowed. In addition, this phenomenon was also observed in other volatile thiols (furfuryl mercaptan, ethyl 2-mercaptopropionate, 2-methyl-1-mercaptobutane, and 4-mercapto-4-methyl-2-pentanone). These compositional changes in thiols that were observed in the air exhaled through the nostrils could be affected by the chemical structure of each tested thiol and individual differences. These results pointed to a possibility that the odorants reaching the olfactory receptor via the throat during consumption of foods could not always retain their original chemical structures and compositions in foodstuffs. Therefore, the characteristic odor of volatile thiols might be perceived due to the stimuli of multiple compounds. To understand in detail flavor perception during the consumption of foods, not only the compositions or amounts of odorants in foodstuffs but also the compositional changes in odorants induced by biological reactions (reduction or methylation) need to be taken into consideration.

In-mouth flavour release from milk proteins

The in-mouth release of flavour (2-nonanone) from whey protein isolate (WPI) and sodium caseinate in aqueous solutions, and the influence of the thickener, sodium carboxymethylcellulose (CMC), on the release of 2-nonanone were investigated using proton-transfer-reaction mass spectrometry. During consumption, a significant release of 2-nonanone from WPI (2%) was observed. After swallowing the samples, a substantial amount of flavour was detected in the breath, suggesting that some sample solution remained in the mouth and throat, resulting in a further release of flavour from proteins. In the presence of CMC, a significant release of 2-nonanone from not only WPI but also sodium caseinate was observed, which may be attributable to the increase in viscosity of the solutions. It is likely that a thicker coating of the mouth and throat with the higher viscosity sample after swallowing results in additional release of protein-bound flavour.

A New Approach to Estimate the In-mouth Release Characteristics of Odorants in Chewing Gum

The objective of this study was to develop a new approach that can be used to estimate the in-mouth release characteristics of odorants in chewing gum. This technique, called the “Retronasal Flavor Impression Screening System (R-FISS),” is based on a modified dynamic headspace gas sampling technique. By application of the R-FISS technique, the in-mouth release characteristics of odorants during the chewing of gum was indicated by the peak area ratio, which was calculated by comparing the peak area for 10 min to the peak area for 1 min, of each odorant exhaled from the human nose. In addition, a good overall regression coefficient was found for the correlation between the peak area ratios of each odorant in the model chewing gum obtained by R-FISS and the retention indices on a polar stationary phase GC column (DB-Wax). Therefore, the in-mouth release of odorants in chewing gum seems to be capable of being predicted by their RIs on a polar stationary phase GC column (DB-Wax), and these results appear to suggest that two parameters (vapor pressure and hydrophobicity/hydrophilicity) are the key factors for determining the in-mouth release of odorants from chewing gum.

A mathematical model of volatile release in mouth from the dispersion of gelled emulsion particles

This paper presents a mathematical model of in-mouth volatile release from gelled emulsion particles dispersed in a continuous aqueous phase. Data based on APCI MS-Breath analysis is presented to demonstrate the effect of particle size, oil content and oil–water partition coefficients. It is shown that in-mouth release of aroma from the dispersion of gelled emulsion particles follows a two-component kinetic equation with fast and slow components. Both the fast and slow rate constants depend on the particle size, oil content and oil water partition coefficient of the aroma. The relative amount of aroma contributing to the fast and slow components also depends on the size of the particles. In order to understand this unexpected behaviour, an analytical model was developed that considers the interplay between the mass transfer of flavour across the interface of the particles and that across the air–liquid interface. Analytical expressions for the two rate constants and the relative ratio of aroma contributing to the fast component have been derived. From this model, three regimes of in-mouth release of aroma from the dispersion of gelled emulsion particles were identified including, the emulsion regime, the transition regime and the gel particle regime. In the emulsion regime, changes in the size of gelled emulsion particles had negligible impact on the overall release. In the transition regime, the release was controlled by the interaction of flavour transfer from the particles with that across the air–water interface. In the gel particle regime, aroma release at long times was governed by the particles and that at short times was governed by the air–water interface, and the two processes were fully decoupled. A simple relationship was derived for the critical size above which the release of aroma from the dispersion of gelled emulsion particles is affected by the size of the particles.

Exhaled Odorant Measurement (EXOM) — A New Approach to Quantify the Degree of In-mouth Release of Food Aroma Compounds

Physiological factors influencing the transfer of volatiles from the oral cavity into the nose were studied. Special attention was paid to the act of swallowing and to effects caused by mouth or tongue movements. The investigations were carried out first with helium, then with aqueous odorant solutions using a novel approach called EXOM (exhaled odorant measurement)-concept. Therefore, the amounts of ethyl butanoate being exhaled through the nose during eating at distinct time intervals were quantified by application of stable isotope dilution assays after trapping of the odorants on TenaxTM.