How does real ale achieve carbonation?

Real ale achieves carbonation primarily through the natural process of yeast consuming sugar during fermentation. This method is rooted in traditional brewing practices, where the beer undergoes a secondary fermentation in the cask. During this stage, any residual sugars that remain in the beer are consumed by the yeast, which then produces carbon dioxide as a byproduct. This naturally occurring CO2 is what creates the carbonation in the beer, contributing to its texture and mouthfeel.

The process of bottle conditioning, similar to cask conditioning in real ale, reflects how flavors and carbonation develop over time due to this natural fermentation. Yeast activity not only provides carbonation but also enhances the complexity of flavors within the beer. This contrasts with methods that involve the injection of CO2 or the addition of carbonation drops, which do not allow for the same depth of character that natural carbonation through yeast fermentation provides.