Partitioned glass, a new practical tool to evaluate the origins of perceptive interactions in wine

Examples of perceptive interactions effects among volatiles on the fruity aromatic expression of wines have been previously highlighted. It was also shown that non-volatile molecules, such as tannins, impact fruity pool both at sensory and physicochemical level. Perceptive interactions have been described as occurring at four different levels: the first as a pre-sensory one, whereas the three others referred to interactions in the peripheral and central nervous system, at the receptor surface or in the olfactory bulb. An original protocol has been conceived to evaluate the odour modulation in binary mixtures: each compound was placed in a separate bottle, the two bottles being individually and simultaneously placed in a larger container, whose odour was evaluated. Thus, the resulting odour came from a mixture of these compounds in gaseous phase and not from the mixture in liquid phase, thus avoiding physico-chemical effects linked to physical mixture. Inspired by this work, an innovative methodological tool was developed to study if perceptive interactions were only due to headspace phase modifications after components mixture. An ISO wine glass with two identical compartments at the filling part was conceived. Such a glass, which is used like a conventional ISO wine glass by the taster, allowed to compare the perceived odour resulting from the mixture or not of the components in each compartment. Triangular tests were conducted to validate if the orientation of the wall separating the two compartments in the horizontal plane was perceived by the panel (4 positions evaluated: N-S, NE-SW, E-W and SE-NW). For each glass, fruity pool and tannins were added separately in each compartment. No significant difference was observed, indicating that the orientation of the glass had no effect on the global perception of the mixture. Various concentrations of fruity pool were also tested, between 25 and 200% of average concentrations found in wine. Finally, triangular tests were again conducted: the odour of a mixture of tannins and the fruity pool in both compartments was compared to the odour of tannins and the fruity pool separated in each compartment. The panel was able to significantly differentiate them. This data proved the existence of pre-sensory interaction between tannins and the fruity pool, thus permitting to understand results observed in a previous study with conventional ISO glass. This new sensory tool was also used to characterise further perceptive interactions we have previously identified, thus revealing additional highlights to physico-chemical changes observed with analytical tools and permitting to elucidate interaction origins