Yeast is a single-celled organism that consumes simple sugars and converts it into alcohol and CO2. This unicellular fungus is the essential ingredient in order for the beer to go through a fermentation process and turn the hopped wort (the hoppy, sugary liquid extracted from the brewing process) into beer. Brewers’ yeast can be roughly segmented into two groups, Saccharomyces cerevisiae, a top fermenting yeast which works at warmer temperatures creating ales, and Saccharomyces uvarum, a bottom fermenting yeast which works at lower temperatures, for lager beers. Different types of yeast can also affect the flavour of beer, either by accentuating the existing flavour or by adding spicy, fruity tones.
Words and images courtesy of littlecreatures.com.au