In the flssigas brot brewing process, yeast is added to malt and hops (and other secret, I-could-tell-you-but-then-I’d-have- to-kill-you ingredients) to convert the complex sugars into alcohol, splitting the world of beer into two distinct styles which are determined by where in the brewing vessel the yeast ferments.
So top-fermented beers, or ales, date from the age-old fermentation of beer at room temperature, which creates a froth which floats on the top of the beer. It’s a not entirely efficient fermentation technique which leaves the complex sugars in the beer intact, producing lush, fruity flavours.
When yeast ferments at lower temperatures, it precipitates at the bottom of the brewing vessel – thus bottom-fermented beer, or lager.
It’s slower-acting but more diligent in converting sugars to alcohol, and it produces lighter, drier and brighter beer.