Fermentation

Until now we've been making sweet hop tea. Beer happens here — and yeast makes it, not us. The brewer has exactly one job: create conditions where the yeast is happy, then get out of the way.

Yeast converts sugar into alcohol and carbon dioxide. Along the way it also produces esters and phenols — compounds that give beer notes of banana, clove, apple or pear. How much of them appears depends mostly on temperature. A warmer ferment means more fruity aroma; a cooler one means a cleaner, more neutral beer.

This is where beer's basic split comes from. Top-fermenting yeast works at 18–24 °C, fast and expressive — those are ales. Bottom-fermenting yeast works at 8–14 °C, slow and clean — those are lagers. The same wort with two different yeasts gives two completely different beers.

The cylindroconical tanks you can see have a cone-shaped bottom. When the yeast finishes, it settles into that cone where we can simply harvest it — often to pitch into the next brew.