Yeast for Home Brewers: Basics and Practical Tips

Yeast is an essential ingredient in brewing, but it is often absent

sufficiently appreciated by beginner homebrewers. In this article, we will discuss the types of yeast, their role in beer fermentation, and give some practical tips on how to choose and use yeast in home brewing.

Yeast Species

There are two main types of yeast used in brewing: but yeast (Saccharomyces cerevisiae) and lager yeast (Saccharomyces pastorianus).

Ale Yeast

Ale yeast ferments at a higher temperature (15-24°C) and is responsible for the production of most types of ale. They produce more esters and phenols, which give beer fruity and spicy aromas. Popular types of ale yeast include:

• American Ale : This yeast provides a clean, light flavor that allows the hops and malt flavors to shine through.
• Belgian Ale : This yeast produces more esters and phenols, giving the beer complex aromas of fruit and spices.
• English Ale : This yeast gives the beer subtle fruity and malty notes.

Lager Yeast

Lager yeast ferments at a lower temperature (7-13°C) and is used in the production of lager beers. They produce cleaner, less aromatic beer. Popular types of lager yeast include:

• German Lager : Offers a clean, smooth taste with subtle malt notes.
• Czech Pilsner : This yeast gives the mild, crisp flavor typical of Czech pilsner varieties.
• American Lager : Produces a very clean, light flavor befitting an American pale lager.

The Role of Yeast in Fermentation

Yeast is responsible for converting sugar into alcohol and carbon dioxide through the fermentation process. It is a complex biochemical process that depends on several factors:

Temperature

Fermentation temperature has a significant influence on yeast activity and the final taste of the beer. Temperatures that are too high can cause unwanted esters and phenols to form, while temperatures that are too low can slow down or stop fermentation altogether.

Aeration

Before starting fermentation, it is important to aerate the wort (unfermented beer) well. Yeast needs oxygen to reproduce and successfully start fermentation.

Amount of yeast

Using too little yeast can cause slow or incomplete fermentation, while too much yeast can cause off-flavors. There are various calculators and guidelines available to help you determine the optimal amount of yeast based on wort density and volume.

Yeast Use and Care

Yeast Reuse

Many homebrewers and commercial brewers use the same batch of yeast multiple times to keep costs down. One of the most popular methods is the so-called "cone-to-cone" method, where the yeast mass from one fermentation is transferred to a new wort using a hose and a pump. The advantages of this method are obvious: there are almost no additional costs, no special equipment is required, and the yeast can be used 10 or more times.

Disadvantages and Risks

However, this method also has its drawbacks. It is important to synchronize the end of fermentation with the production of new wort, and there are also risks to the health and vitality of the yeast. It is not always possible to know exactly how many yeast cells there are in each milliliter of mass, whether they are viable, whether there is genetic drift or microbial contamination.

Yeast Storage

Various containers can be used to store yeast, from plastic containers to specially adapted stainless steel containers called "yeast brink". Yeast is kept cold to remain viable for a few days or a week. However, without laboratory support, it is difficult to ensure yeast health, which can lead to undesirable results.

Yeast Promotion

Large regional breweries such as Sierra Nevada and New Belgium use advanced yeast propagation systems to ensure the health and abundance of their cultures. However, such systems are out of reach for most small brewers.

"Two-turn Grow-up" Method

Many small bravuras use a simpler method called "two-turn grow-up". This makes it possible to reduce the required amount of yeast by using its rapid growth. The brewer half-fills the fermenters with wort and adds the right amount of yeast. Overnight, the yeast grows enough to ferment double the amount of wort. The brewer then fills the fermenter with the second batch of wort. The yeast is thus prepared for vigorous fermentation.

Example from Practice

One brewer that uses a full yeast propagation system is Old Nation Brewing from Williamston, Michigan. They grow their own yeast from small cultures to full commercial batches. Old Nation uses a special yeast propagation tank with an internal impeller, oxygen injection and precise measurements. They make a special wort recipe that is enriched with yeast nutrients and enough hops to "condition" the yeast.

Yeast Care and Love

Yeast is vital to the brewing process, so it is very important to take care of it properly. The best brewers are those who constantly care about the health of the yeast at every stage of production. Yeast not only ferments the wort, but is also an essential part of the taste and quality of beer. Brewers need to love, respect and understand their yeast in order to make great beer.

Conclusion

Yeast is the soul of beer, and making truly great beer requires understanding every aspect of yeast, from propagation to fermentation and harvesting. By taking good care of their yeast, homebrewers can achieve amazing results.