Upgrading a Laser-Based Spectrometer for the Mapping of Gas-Phase CO2 in the Headspace of Champagne Glasses

The laser group of the Groupe de Spectrométrie Moléculaire et Atmosphérique (GSMA, Reims, France) has developed various laser spectrometers for the study of the atmospheres [1]. Based on this technology we developed the same type of instrument for enological studies conducted by the Effervescence team of GSMA. A diode laser detection system for the measurements of gas-phase carbon dioxide (CO
₂
) above a glass of bubbly drink such as champagne has been designed [2]. In champagne and sparkling beverages in general, the progressive desorption of CO
₂
dissolved in the liquid phase is responsible for bubble formation. Moreover, dissolved CO
₂
may also escape by diffusion at the air-champagne interface. A first step in the understanding of the role of CO
₂
was to precisely measure its concentration above champagne glasses, under standard tasting conditions [3]. To address this purpose, many optimizations of the set-up have been realized. First the original 2.68 μm diode laser was coupled to an optical fibre to prevent from atmospheric CO
₂
interferences. Then, a second laser emitting around 2 μm was adapted to realize measurements with large concentrations of CO
₂
. Finally, the whole set-up, namely the CO
₂
-DLS, was driven by a LabView ® program in order to automatically record the temporal evolution of gas-phase CO
₂
concentration in one position of the headspace above liquid [4]. A set of data showing the impact of champagne temperature and volume as well as the intensity of effervescence on the release of gas phase CO
₂
was realized [5].