YEAST: ESSENTIAL INGREDIENT FOR BEER

Yeast is the ingredient responsible for the fermentation process that transforms wort into beer. Yeasts are a group of fungi formed by a single type of eukaryotic cell, and there are more than a thousand yeast species.

TYPES

The yeasts used for beer production can be classified into two categories, high and low fermentation. This division was presented by Danish mycologist Emil Christian Hansen.

• High fermentation: it is called so because it floats on the surface of the beer. This yeast prefers high temperatures (12-24°C) and gives the beer a fruity and spicy aroma.
• Low fermentation: on the contrary, this yeast works at low temperatures (7-13°C) and then settles on the bottom..

Saccharomyces cerevisiae (known as brewer's yeast) is the most classic high fermentation yeast and is used in "ale" type beers. Among the low fermentation yeasts, there are Saccharomyces uvarum and Saccharomyces carlsbergensis. Both are used in the production of "lager" type beers.

FUNCTIONS

The task of this beer ingredient is to metabolize the sugars in the wort, which was obtained during the mashing process. In this way, particular flavors and the characteristic alcoholic content are attributed to beer.

CHARACTERISTICS TO CONSIDER

Since yeast gives the flavor of beer, it is necessary to pay attention to some characteristics when choosing the type of yeast::

• The origin
• The fermentation temperature
• Flocculation: it's the yeast's ability to gather in clumps and settle at the bottom of the fermenter. Yeasts with high flocculation make clearer beers, while those with low flocculation result in less clarity..
• Alcohol resistance: it's the yeast's ability to resist alcohol.
• Attenuation: it's the yeast's ability to metabolize sugars and balance the sweet/bitter ratio. Yeasts with a high percentage will create more alcoholic and dry beers (more bitter). Instead, those with a low percentage will make the beer more full-bodied and with a stronger malt flavor (sweeter).