9 But the bubbles aren’t the only way in which the


CO2 leaves the champagne, the CO2 also escapes by diffusing through the contact surface of the champagne with the air. Experiments were performed a few years ago on the


respective losses of CO2 during the pouring of champagne in a flute (published in 2002 in Annales de Physique) and it was found that for


every single CO2 molecule which escapes from the champagne in the form of bubbles, four others directly escape by diffusion through the free contact surface of the champagne with the air. Diffusion is therefore strongly suspected to be the main pathway through which dissolved


CO2 escapes during the pouring of a glass of champagne.


When pouring champagne, the sparkling fluid forms a jet – or tongue – as it falls from the bottle into the glass. This effect partly explains


the difference in CO2 loss, according to Guillaume Polidori. “With the traditional way of serving, this tongue is much longer than with the beer-method. This means that the contact surface of the champagne with the air is significantly smaller if you pour the champagne like beer. We think that this also partly explains the difference between the two pouring techniques.”


The thermal image clearly shows that less CO2 escapes if the glass is tilted while pouring champagne with the ‘beer-like’ way of serving.


Making the Diffusion Process Visible


As the diffusion process is invisible to the human eye – measuring it presented the researchers with a challenge. The solution to this challenge proved to be a thermal camera. “We used the


FLIR SC7000 series thermal camera to film the CO2 as it dissipated during the pouring process. This visually confirmed what the test results showed,” explains Guillaume Polidori.


Concentrations of dissolved CO2, as chemically measured once champagne


was poured into the flute, for both ways of serving champagne and for each champagne temperature.


The loss of CO2 in the champagne is clearly higher with the ‘traditional’ way of serving.


“We were even contacted by a journalist from the New York Times.” He attributes a large part of this attention to the influence of the thermal cameras. “Just scientific data isn’t as spectacular – or as convincing – as when you can see it with your own eyes. So thermography played a very important role in this research both to confirm our data and visualise it.”


Very Specific Bandwidth


But visualising the CO2 emission wasn’t as easy as just pointing a thermal camera at the champagne glass. GRESPI researcher Hervé Pron mostly worked with the FLIR camera. He


explains why it’s not that simple: “The CO2 absorptions observable by thermal cameras are quite weak because this gas molecule has only a strong absorption peak in the detector


bandwidth at 4.245 µm. So we needed to look at that specific bandwidth.” To do that the group used an external band-pass filter. “The camera operates at a bandwidth of 3 to 5µm.


To look at the thermal emission from the escaping CO2 we acquired an external band-pass filter that was centered on the CO2 emission peak and only allows infrared that has the bandwidth of the particular wavelength region we need to pass.”


Hervé Pron was pleased with the camera’s performance. “We needed a thermal camera that’s easy to calibrate, very accurate, lightweight, easy to use and has a high resolution. This camera delivered just that. We could see enough detail, without too much background interference, or ‘noise’.”


The SC7000 operates at a bandwidth of 3 to 5 µm, the external filter narrows it down to exactly 4.245 µm.


The external band-pass filter is


centred on the CO2 emission peak.


To visualise the escaping CO2 the researchers used an


external band-pass filter.


The Perfect Champagne Glass


In recent years, glassmakers have proposed to consumers a new generation of champagne tasting glasses, specially designed, with a well controlled CO2 release during the entire tasting process. This has been the driving force behind the rapidly growing interest behind


gaining a better understanding and depicting each and every parameter involved in the release of gaseous CO2 from glasses poured with champagne or sparkling wine.


The ‘traditional’ way of serving champagne clearly produces more bubbles.


The FLIR SC7000 Series is a very flexible open system that can be adapted for any situation possible. It provides the highest possible sensitivity, accuracy, spatial resolution and speed. This series of advanced thermal cameras is specifically designed for academic and industrial R&D applications where you need leading edge sensitivity and performance to produce results. The detector that powers this example of the SC7000 series is a cooled Indium Antimonite (InSb) detector. With a sensitivity of about 20 mK (0.02°C) and an image resolution of 640x512 pixels the camera can make even the smallest temperature differences


visible. The integration time is adjustable in 1 µs increments. Combined with the external triggering mechanism this also allows the SC7000 to capture even the most fleeting of events.


The visual confirmation of the effect of differing pouring techniques on the diffusion process by the SC7000 thermal camera provided the researchers with a further scientific validation of their experimentation, but it also played another crucial part according to Guillaume Polidori. “We wouldn’t get all this press attention if we hadn’t been able to visualise it. That’s how it works: to get published you have to produce solid and interesting new research, but if you want it to get noticed by the press you need a visual trigger as well.” And Guillaume Polidori thinks the thermal camera played its part well.


The next step in champagne research is to produce a complete mathematical model of CO2 dissipation during the pouring process which includes the multiple ways of CO2 discharge during the pouring process. This model is under construction, according to Guillaume


Polidori. “I can’t say too much but we’re working on it. But if we pull it off that would be a very useful discovery, as glassmakers could use that model to design the perfect champagne glass.”


Article written with the following references:


Physicochemical approach to the effervescence in Champagne wines Liger-Belair, G. 2002 Annales de Physique 27 (4) 4.


Source of certain figures and images: On the losses of dissolved CO2 during champagne serving by Liger-Belair, G., Bourget, M., Villaume, S., Jeandet, P., Pron, H., Polidori, G. 2010 Journal of Agricultural and Food Chemistry


58 (15), pp. 8768-8775.


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