Measuring Dissolved CO2
Definition and Relevance
Carbon Dioxide, CO2, dissolves in water and wine up to around one g/L at room temperature and normal air pressure. The amount decreases with rising temperatures and falling ambient pressure.
Fermentations create a lot of CO2, as sugar is converted into alcohol. CO2 bubbles up and forms a blanket on the top of the must in the fermentation tank, preventing the growth of microorganisms on the cap. When the fermentation is complete, no further CO2 is produced, the amount of dissolved CO2 stabilizes, and the wine must be protected by other means from contact with oxygen.
Small amounts of dissolved CO2 give the wine a fresh taste. Particularly in Bordeaux, winemakers often adjust the level of dissolved CO2 to 500-800 ppm in red wines and a bit higher in whites. Adding dry ice is the easiest way to add CO2 to wine at low cellar temperaures before bottling. A good rule of thumb is that about half the dry ice added will dissolve in the wine, and the other half will bubble up. So, the amount of dry ice to be added can be calculated as follows:
Dry Ice Add [in gram] = Amount of wine [in Liters] * Desired Increase in Dissolved CO2 [in ppm] * 0.002
Measurement
We measure dissolved CO2 with a Cabodoseur – an old-fashioned French mechanical tool that measures the amount of CO2 that escapes wine when it is vigorously agitated. The picture on the right shows the instrument
Previous page: Measuring Dissolved Oxygen
Top of page: Go
Next Page: Measuring Brix
Last updated: March 31, 2023