What is DCO2?
Carbon Dioxide is a colourless gas composed of one carbon atom and two oxygen atoms. When water is present CO2 will dissolve into the liquid (producing dissolved CO2) and a reaction will occur leading to the production of carbonic acid. Carbonic acid is a very weak acid but it contributes to why wines with more CO2 “give a hint of tartness”.
We have all probably experienced the feeling of being punched in the face by carbon dioxide during harvest. This is because carbon dioxide is a by-product of fermentation, in a process in which -put simply- yeast converts sugar into ethanol and carbon dioxide.
During fermentation the wines become saturated with CO2, however post-fermentation the CO2 reduces due to processes such as rackings and cold stabilization. The amount of CO2 lost post-fermentation depends on its solubility.
- Solubility: Solubility is a property referring to the ability for a given substance, the solute, to dissolve in a solvent.
Factors that will impact the CO2’s solubility (or the amount lost) include temperature and alcohol content. For example, warming will reduce the CO2’s solubility and therefore result in a reduced level of CO2.
Not only is Carbon Dioxide produced during alcoholic fermentation it is also an essential aspect of the finishing stages of the wine-making process. Carbon dioxide is sometimes introduced to wine, or reduced to desired levels depending on the style of wine. If a Sauvignon Blanc has too little gas it can be perceived as “lacking freshness”, and too much gas can make it uncharacteristically “spritzy”.
In the finishing stages of the winemaking process it becomes important to have instruments to measure the amount of CO2 in a wine so it can be adjusted to desired levels.
One instrument for measuring dissolved CO2 is the “Carbodoseur”, it is readily used as it is an easy test and relatively cheap. However, it is not always accurate as there are a lot of factors which could give false readings.
Using the Carbodoseur involves the following steps:
- Take temperature of wine sample.
- Fill the cylinder with sample holding Carbodoseur at an angle (fill until meniscus is at 100mL).
- Fasten lid firmly.
- Hold finger over central tube and shake vigorously.
- Remove finger from centre tube to allow wine to escape.
- Repeat process of shaking then removing finger until no more wine escapes from central tube.
- Remove lid and measure the volume remaining in the cylinder.
- Use the supplied table (taking the final cylinder measurement, and temperature) to determine the DCO2.
Measuring dissolved CO2 in the winery. (2016, August). Vintessential.Com.Au. https://www.vintessential.com.au/tip-measuring-dissolved-co2-in-the-winery/
McDonald, C., & Baguley, R. (2015, August). Appliance Science: The compressed chemistry of carbonation. https://www.cnet.com/news/appliance-science-the-compressed-chemistry-of-carbonation/
B.W. Zoecklein. (n.d) GASES: CARBON DIOXIDE, ARGON, AND NITROGEN. https://www.apps.fst.vt.edu/extension/enology/downloads/wm_issues/Winery%20Gases/Winery%20Gases1.pdf
Lyrebird_cycles. (December, 2017). Measuring CO2. [Photograph]. Aussie Home Brewer. https://aussiehomebrewer.com/threads/measuring-co2.97298/