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

Context: When 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. Method: We used a twofold approach: 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. In-mouth release of volatile compounds was measured by nosespace analysis with the same panelists. Results: Acid concentration influenced aroma compounds release, but it did not impact perceived aroma intensity. 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

Retronasal Aroma of Beef Pate Analyzed by a Chewing Simulator

International audienceIn retronasal aroma, the targeted aroma compounds are released from food during chewing. The changes in the food structures during chewing strongly influence the release of the compounds, therefore affecting the perception of food. Here, the relationship between retronasal aroma and food deliciousness based on the physicochemical properties of aroma compounds was examined. We considered the consumption of solid foods and the effect of oral parameters in elderly people. Beef pate was used as a model food sample to study the effect of the release of aroma compounds under controlled in vitro mastication and salivation conditions using a chewing simulator. We identified the effects of coexisting ingredients such as beef fat on the time course behavior of the release of aroma compounds. In particular, the release of the middle types of aromas was significantly faster with stronger chewing force, and higher with a high fat content of the sample. In addition, a larger release intensity was observed when soy proteins were partially substituted for beef proteins. Using an appropriate model saliva, a change in the salting-out effect from the saliva composition was found to be a factor, which could explain the lowering of aroma sensation in an elderly person

Burial behaviour by dealates of the termite Pseudacanthotermes spiniger (Termitidae, Macrotermitinae) induced by chemical signals from termite corpses

In order to maintain healthy colonies, termite workers dispose of the cadavers of dead nest mates by cannibalism, burial, or necrophoresis. However, when multiple reproductives found a new colony by pleometrosis, there are no worker castes at the early stages of the foundation to eliminate or isolate the corpses. In this study, we showed that in young pleometrotic colonies, reproductives of Pseudacanthotermes spiniger had the ability to perform this task. Because of the claustral conditions, and the potential inability of the dealates to feed on their own, their behaviour was restricted to the burial of the cadaver within the initial chamber. This burial behaviour, previously not reported in the reproductive caste of termites, appeared to be induced by chemical signals released by the corpses during decomposition, among which various fatty acids, indole and phenol were the most active. The burial finally resulted in the physical isolation of corpses, thus reducing the chances for opportunistic pathogens to spread among the rest of the individual

PTR-SRI-ToF-MS analysis of aroma compounds: influence of drift tube E/N ratio on sensitivity and fragmentattion

Livre ISBN-13 : 978-3-902811-91-2International audienceThe aim of this work was to compare detection and fragmentation patterns of aroma compounds obtained with three different precursor ions and several E/N source parameter values with the proton transfer reaction (PTR-MS) methodology. The reactant ions H3O+, NO+ and O2+. were generated in a Switchable Reagent Ions (SRI) source of a PTR-ToF-MS (Ionicon 8000, Innsbruck, Austria). Precursor ions plasmas were characterized at different E/N ratio in the drift tube. For proton transfer reaction, the hydronium primary ion was the most abundant ion (> 80%) for all E/N ratios above 120 Td, but the sensitivity decreased quickly with the highest E/N values. Even though NO+ was the most abundant primary ion in the ion plasma formed from ambient air, contaminant ions were detected with high (O2+. and NO2+) or medium (H3O+) intensities. For O2+. generated from pure oxygen, O2+. was the main precursor ion, the presence of contaminant ions was limited to a few percent of H3O+ at low E/N ratios and the reactant ion production increased significantly with increasing E/N values. The mass spectra of 12 aroma compounds belonging to various chemical classes were recorded in the three ionization modes at different E/N values. Although H3O+ ionization generally displayed limited fragmentation with increasing E/N ratios (essentially with acids, esters and some alcohols), the sensitivity decreased significantly with increasing E/N values, mainly above 120 Td. For NO+ ionization, expected charge transfer or hydride abstraction reactions were in competition with proton transfer reaction due to the presence of contaminant primary ions. O2+. ionization, the most energetic charge transfer reaction, displayed enhanced fragmentation, not always sensitive to increasing E/N values. For both NO+ and O2+. ionizations, the global sensitivity decreased significantly with increasing E/N ratios

Optimization of the ion plasma formation in a switchable reagent Ions (SRI) proton transfer reaction-mass spectrometry system

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(Z)-Dodec-3-en-1-ol, a common major component of the trail-following pheromone in the termites Kalotermitidae

10.1007/s00049-009-0017-7Abstract (Z)-Dodec-3-en-1-ol has been identified as the major component of the trail-following pheromone of nine species of Kalotermitidae belonging to six different genera, suggesting that this compound represents a common signal in this family of termites. The homogeneous nature of trail-following pheromones of Kalotermitidae well agrees with the monophyly of this family. It also supports the postulated position of this family as a sister group of the Rhinotermitidae and Termitidae, which also secrete C12-alcohols as trail-following pheromones. The significance of a trail pheromone in termites of the ‘one-piece' life type, which spend their whole life within the same piece of wood, is discussed

L1: Oral processing behaviours and retronasal aroma release variability during cheese consumption in human

Abstract of oral presentatio