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International audience; The perception of thousands of odours by about 380 human olfactory receptors (ORs) results from a combinatorial coding, in which one OR recognizes multiple odorants and odorants are recognized by different combinations of ORs. We used data of 95 odorant molecules tested on two human ORs, OR1G1 (class II) and OR52D1 (class I), to perform a 3D molecular modelling study of ligands using Catalyst/HypoGen software. The sorting-out procedure previously used for OR1G1 ligands was transposed to OR52D1 ligands. The 3D-QSAR models obtained for OR1G1 and OR52D1 ligands essentially differ by distance between their features. This result suggests a path to decipher the odotopes of OR1G1 and OR52D1 agonists in order to investigate the role of ORs in olfactory coding.

International audience; Rice from two scented (Aychade, Fidji) and one nonscented (Ruille) cultivars from Camargue area (France) together with one Asian scented rice (Thai) were cooked and volatile compounds were extracted by dichloromethane/pentane (1;2, v/v) solvent mixture. 40 odorous compounds were noticed during GC-O analysis of the organic extracts, amongst which oct-1-en-3-one and 2-acetyl-1-pyrroline were altmost constantly perceived. Hierarchical cluster analysis (HCA) of perceived odours enabled to distinguish the groups of rice cultivars. 60 compounds were identified and quantified by GC-MS. New odour-active components of cooked rice were detected for the first time including oct-3-en-2-one, 2-methylpropanoic acid, y-decalactone and o-decalactone. A principal component analysis (PCA) differentiated scented cultivars from a non-scented one and scented rice cultivars from Camargue from Thai sample.

International audience; Understanding in-mouth mechanisms is necessary to understand flavour release and perception phenomena. To overcome the limitations of in-vivo flavour release measurements, we developed a chewing simulator that faithfully reproduced many mouth functions. Using brittle foods, we showed that in-vitro food breakdown was very comparable to that obtained in-vivo. We also studied on model cheeses in-vitro flavour release by connecting on-line the chewing simulator to APCI-MS. Preliminary results are discussed.

International audience; Pectin and carrageenan are common used thickeners in fat free foods. The aim of this work was to study separately and to compare their respective effects on the aroma release, in order to investigate the nature of involved interactions. In this way, we studied the influence of the chemical structure of 13 aroma compounds on retention/release equilibrium between vapour phase and gels using QSPR tools. Six descriptors are involved in the best obtained QSPR equations, and three of them appeared to play a critical role in the behaviour of aroma compound. Our results put forward the role of polar effects on the retention of odorant molecules in both iota-carrageenan and pectin gels, indicating that iota-carrageenan polymer do not change the interaction between aroma compounds and water molecules, whereas pectin causes slightly different interaction involving positive charged surfaces areas in the retention phenomenon.

International audience; The influence of the texture on perceived aroma intensity and on in-vivo and in-vitro aroma release was investigated on three types of dairy products, prepared with different textures. Aroma release depends on in mouth breakdown of the product. The consequences of a textural modification on aroma perception were not the same for the different products. In the case of liquid to semi-liquid products (yogurt and custard dessert), in-vivo aroma release decreased when viscosity increased. For firm gels (model cheeses) in-vivo aroma release was found to increase when cheese hardness increased, but inverse results were obtained in in-vitro conditions. Thus, aroma release could explain perceived aroma intensity for yogurts but not for cheeses for which large inter-individual differences were observed. An adaptation of the chewing pattern was supposed in-vivo leading to high structural modifications.

International audience; On the basis of a first mechanistic model predicting aroma release in the oropharynx during food consumption, the aim of the present work was to improve its accuracy and to use it to identify the main mechanisms responsible for in-mouth aroma release. Comparison between predicted release kinetics and the ones measured by APCI-MS in the nasal cavity of subjects eating flavoured yogurt highlighted the reasonably accurate time predictions of the relative aroma concentration in the nasal cavity and the model ability to simulate successive swallowing events as well as partial velopharyngeal closure. Parameters identified as the most influent for in-vivo aroma release were related to either physico-chemistry (equilibrium air/product partition coefficient, mass transfer coefficient in the product), physiology (the volume of the nasal cavity, breath airflow rate) or interaction between both (the amount of residual product in the pharynx, air/product contact area).