| KnowledgeBase / Yeast |
Yeastwritten by: - 151 viewsBeer brewers classify yeasts as top-fermenting and bottom-fermenting. Top-fermenting yeasts are called this because they form a foam at the top of the wort during fermentation. They can produce higher alcohol concentrations and prefer higher temperatures, producing fruitier ale-type beers. An example of a top-fermenting yeast is Saccharomyces cerevisiae, known to brewers as ale yeast. Bottom-fermenting yeasts are used to produce lager-type beers. These yeasts ferment more sugars, leaving a crisper taste, and grow well at low temperatures. An example of a bottom-fermenting yeast is Saccharomyces pastorianus.For both types, yeast is fully distributed through the beer while it is fermenting, and both equally clump together and precipitate to the bottom of the vessel when it is finished. By no means do all top-fermenting yeasts demonstrate this behavior. In industrial brewing, to ensure purity of strain, a 'clean' sample of the yeast is stored refrigerated in a laboratory. After a certain number of fermentation cycles, a full scale propagation is produced from this laboratory sample. Typically, it is grown up in about three or four stages using sterile brewing wort and oxygen. See our yeast list. |
Comments |
Add Comment |
