CO2 Analysis – Management of Carbon Dioxide in Still and Carbonated Wines
Carbon dioxide (CO2) is a natural gas produced during fermentation and dissolves in wines. Most of the CO2 is lost during racking and mechanical movements that the wine undergoes in the winery. However, careful handling and low temperatures can help minimize these losses.
The addition of CO2 during winemaking and/or as a preservative can have different effects depending on how and when it is done. Temperature is always a key parameter, as it significantly affects the solubility of the analyte in the aqueous medium.
Carbon Dioxide (CO2) in water produces carbonic acid (H2CO3). Both coexist in equilibrium in wine.
Carbon and Carbonic Equilibrium
CO2 + H2O → H2CO2
H2CO3 → HCO3- + H+ (pKd = 6.35)
HCO3- → CO23- + H+ (pKd = 10.33)
CO2 has direct effects on wine tasting; it can enhance freshness and acidity in the mouth, attenuating sweetness. However, it can also intensify bitterness and astringency.
Wine Types and Their CO2 Levels
- Still Wine: CO2 residual < 1,5 g/L
- Carbonated Wine: CO2 from exogenous origin
- Semi-Sparkling Wine: CO2 pressure 1,5 to 2,5 bar
- Sparkling Wine: CO2 pressure > 4 bar
How We Measure CO2?
In wineries, the determination of dissolved CO2 in wine is measured as activity (partial pressure of CO2 in equilibrium with the solution) during production and before bottling.
Methods For Still and Carbonated Wines Range
- Manual Titration (OIV Official)
BioSystems Method
- Veitshöchheim Test
BioSystems Enzymatic Measurement of CO2
Advantages
- Stable performance
- Accurate working range 0.12-2.5 g/L
- Control standard included
- Automated and fast
- Validated against reference OIV methods
- Simple pretreatment
- Minimum sample volume of 100 mL
The carbon dioxide present in the sample consumes the NADH analogue, which is measured colorimetrically at 405 nm. The decrease in absorbance resulting from the reaction is proportional to the amount of carbon dioxide present in the sample.
CO2 analysis is available on the BioSystems Y15, Y200/Y400 and SPICA analysers.