On the losses of dissolved CO2 during champagne aging
Abstract
A misconception lingers in the minds of some wine consumers that Champagne wines don’t age. It’s largely a myth, certainly as far as the best cuvees are concerned. Actually, during the so-called autolysis period of time (in the closed bottle, after the “prise de mousse”), complex chemical reactions take place when the wine remains in contact with the dead yeast cells, which progressively bring complex and very much sought-after aromas to champagne. Nevertheless, despite their remarkable impermeability to liquid and air, caps or natural cork stoppers used to cork the bottles are not 100% hermetic with regard to gas transfers. Gas species therefore very slowly diffuse through the cap or cork stopper, along their respective inverse partial pressure. After the “prise de mousse”, because the partial pressure of CO2 in the bottleneck reaches up to 6 bars (at 12 °C), gaseous CO2 progressively diffuse from the bottle to the ambient air (where the partial pressure of gaseous CO2 is only of order of 0,0004 bar). Moreover, because gaseous and dissolved CO2 experience thermodynamic equilibrium in the closed bottle (through the so-called Henry’s law), the level of dissolved CO2 also inevitably decreases as time proceeds during aging on lees. Actually, in champagne tasting, the level of dissolved CO2 is indeed a parameter of paramount importance since it is responsible for the bubbling process (the so-called effervescence). Keeping the dissolved CO2 as long as possible inside the bottle during aging is therefore a challenge of importance for Champagne wine elaborators, especially for old vintages collections likely to age on lees for long periods of time. Here, measurements of dissolved CO2 concentrations were done in a collection of various vintages (from a prestige cuvee provided by our partner), initially holding the same level of CO2 after the “prise de mousse” (classically close to 11.5 g/L), but having experienced different periods of aging on lees (ranging from several months up to 35 years). Progressive losses of dissolved CO2 concentrations were evidenced, depending on the period of time spent in contact with lees. Our results were compared with a previous set of experimental data, and with a multi-parameter model recently developed which provides the level of dissolved CO2 in wine as a function of time. It is worth noting that both the diameter of the bottleneck, and the bottle volume, were found to be key parameters as concerns the losses of dissolved CO2 during champagne aging. Equipe Effervescence (GSMA), Université de Reims, France Laboratoire de Recherches, Champagne Moët & Chandon, Epernay, France
Issue: Macrowine 2016
Type: Poster
Authors
*Equipe Effervescence (GSMA)