The Role of CO2 in Brewing Beer

Carbon dioxide (CO2) is essential in the beer brewing process, influencing both production and the final product’s characteristics. Here’s a detailed look at its roles:


During fermentation, yeast consumes sugars present in the wort (the liquid extracted from the mashing process) and converts them into alcohol and CO2. This natural production of CO2 is a byproduct of the yeast metabolism, which is critical for the development of beer’s alcohol content and carbonation. The CO2 produced during fermentation can either be allowed to escape or be trapped to create natural carbonation. Brewers often use fermentation vessels equipped with airlocks or pressure valves to control this process.


Post-fermentation, additional CO2 is often added to achieve the desired level of fizziness in the beer. This can be done through:

  • Bottle Conditioning: This involves adding a small amount of sugar before sealing the bottle, allowing for a secondary fermentation process. This secondary fermentation produces more CO2, naturally carbonating the beer within the bottle.
  • Force Carbonation: This method involves directly injecting CO2 into the beer under pressure. This is a common practice in commercial brewing where consistency and control over carbonation levels are crucial. The beer is placed in a sealed container, and CO2 is forced in until the desired level of carbonation is reached.

Preservation and Dispensing

CO2 also plays a critical role in preserving beer by creating an environment that is inhospitable to aerobic bacteria and other spoilage organisms. During the dispensing process, CO2 is used to push beer from kegs to taps. This not only ensures a consistent flow but also maintains the carbonation levels and freshness of the beer until it reaches the consumer’s glass.

Sensory Impact

The level of CO2 significantly affects the beer’s mouthfeel and flavor perception. Higher carbonation levels create a lively and effervescent sensation, enhancing the perception of lightness and crispness in the beer. Conversely, lower carbonation levels can make a beer feel smoother and fuller-bodied. The bubbles from CO2 also contribute to the release of aromatic compounds from the beer, enhancing its aroma and overall sensory experience.

Show-Me Craft Beer Month

June is celebrated as Show-Me Craft Beer Month in Missouri, highlighting the state’s vibrant craft beer industry. This month-long celebration includes various events and activities:

  • Collaboration Beers: Breweries release unique collaboration beers that showcase their creativity and camaraderie.
  • Special Deals: Growler and crowler deals allow enthusiasts to enjoy their favorite brews at home.
  • Missouri Pint Day: A special day dedicated to enjoying local beers in custom-designed pint glasses.

Missouri is home to over 160 craft breweries, contributing significantly to the local economy and community. Show-Me Craft Beer Month emphasizes the importance of supporting these local businesses and celebrating the artistry behind craft brewing.

For more details on events and how to support local breweries, visit the Missouri Craft Brewers Guild website.

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