How is yeast used in the brewing industry?

Yeast is used in the brewing industry to ferment sugars into alcohol, producing beer.

In the brewing industry, yeast plays a crucial role in the fermentation process, which is the transformation of sugars into alcohol. This process begins when the brewer mixes yeast with a sugary liquid known as wort, which is derived from malted barley. The yeast cells consume the sugars in the wort, breaking them down through a process called anaerobic respiration. This process produces alcohol, carbon dioxide, and other by-products that contribute to the flavour and aroma of the beer.

There are two main types of yeast used in brewing: Saccharomyces cerevisiae, which is used for ales, and Saccharomyces pastorianus, used for lagers. These yeasts differ in their fermentation temperatures and the types of flavours they produce. S. cerevisiae ferments at warmer temperatures and tends to produce fruity and spicy flavours, while S. pastorianus ferments at cooler temperatures and produces cleaner, more crisp flavours.

The yeast also plays a role in the carbonation of the beer. The carbon dioxide produced during fermentation is trapped in the beer, giving it its characteristic fizz. In addition, the yeast contributes to the beer's foam or 'head', which is created by proteins in the beer interacting with the carbon dioxide.

The yeast used in brewing is often a carefully selected strain, chosen for its ability to produce a specific flavour profile or to perform well under certain brewing conditions. Brewers may use a single strain of yeast, or they may use a blend of different strains to achieve a particular flavour complexity.

In summary, yeast is a vital component in the brewing process. It not only converts sugars into alcohol, but also contributes to the flavour, aroma, carbonation, and foam of the beer. Without yeast, the brewing of beer would not be possible.