Conditioning & Lagering

Young beer is beer, but it isn't good beer yet. It still holds compounds the yeast left behind: diacetyl, which smells of butter or butterscotch, and acetaldehyde, which reads as green apple.

The fix isn't filtration, it's time. Leave the beer resting on its yeast for a few more days and the yeast takes those compounds back up and processes them. Brewers call it a diacetyl rest.

Then the temperature drops, close to freezing. In the cold, yeast, proteins and hop particles settle out, the beer clears, and sharp flavour edges soften. Lager is named after this step — German lagern means to store.

For some styles it takes a week; for classic lagers it can take two months. This step can't be rushed, only skipped — and skipping it is immediately obvious in the glass.