Yeast flocculation

Yeast flocculation typically refers to the clumping together (flocculation) of brewing yeast once the sugar in a wort has been fermented into beer.In the case of "top-fermenting" ale yeast (Saccharomyces cerevisiae), the yeast creates a "head" on the top of the liquid, unlike with "bottom-fermenting" lager yeast (Saccharomyces pastorianus) where the yeast falls to the bottom of the brewing vessel.