The Down-Low on Lager Yeast

The Down-Low on Lager Yeast

Lager yeast is a bottom-fermenting yeast that is used in the production of lager beer. It is an essential ingredient that contributes to the unique characteristics of lager beer, including its crisp, clean flavor and smooth finish. In this blog post, we will take a closer look at what makes lager yeast different from ale yeast, and discuss the temperatures at which lager yeast performs best.


Lager yeast is classified as Saccharomyces pastorianus, which is a hybrid of two different yeast species, Saccharomyces cerevisiae and Saccharomyces eubayanus. This hybridization likely occurred spontaneously in nature, possibly in the cool climate of the Andes Mountains, where S. eubayanus is thought to be native. It is believed that S. pastorianus then traveled with European immigrants to the continent and was first used to brew lager beer in the early 19th century.

S. pastorianus is well adapted to the cool fermentation temperatures required for lager beer production and is highly tolerant of low temperatures. It is also capable of metabolizing a variety of sugars, making it a versatile yeast strain that can be used to produce a wide range of lager beer styles.

One of the challenges of using lager yeast is that it can be more difficult to handle than ale yeast due to its slower fermentation rate and the need for cooler fermentation temperatures. However, with proper fermentation management and a good understanding of the characteristics of the yeast strain being used, brewers can produce high-quality lager beer that showcases the unique flavors and aromas that lager yeast provides.

In summary, lager yeast is a hybrid yeast species, Saccharomyces pastorianus, that is adapted to cool fermentation temperatures and is highly tolerant of low temperatures. It is a versatile yeast strain that can be used to produce a wide range of lager beer styles, and with proper management, it can produce high-quality lager beer that showcases its unique flavor profile.

What Makes Lager Yeast Different Than Ale Yeast?

The main difference between lager yeast and ale yeast is the temperature at which they ferment. Ale yeast is a top-fermenting yeast that ferments at warmer temperatures (around 60-75°F) for a shorter period of time (usually 5-7 days). Lager yeast, on the other hand, is a bottom-fermenting yeast that ferments at cooler temperatures (around 45-55°F) for a longer period of time (2-3 weeks or more).

This difference in fermentation temperature and time leads to distinct differences in the flavor and aroma of the resulting beer. Lager yeast produces a much cleaner, crisper flavor with fewer fruity or spicy notes than ale yeast. It also ferments more slowly and produces fewer esters, which are responsible for the fruity or spicy flavors that are characteristic of ales.

At Which Temperatures Does Lager Yeast Perform Best?

Lager yeast performs best at cooler temperatures than ale yeast. This is because the lower temperatures slow down the fermentation process, allowing the yeast to produce a cleaner, crisper flavor. However, lager yeast is still active at these cooler temperatures, so it is important to keep the temperature consistent during the fermentation process.

Most lager brewers will ferment their beer at around 50°F, but some will go as low as 45°F. It is important to note that different strains of lager yeast may have different optimal temperatures, so it is always best to consult the manufacturer’s recommendations for the specific strain you are using.

In addition to fermentation temperature, it is also important to consider the pitching rate (the amount of yeast added to the wort) when using lager yeast. Due to the slower fermentation rate of lager yeast, it is recommended to pitch a higher amount of yeast than when using ale yeast. This will ensure that the yeast is able to effectively ferment the wort and produce the desired flavor profile.


Lager yeast is a critical ingredient in the production of lager beer, and the unique characteristics it provides are what set lager beer apart from other styles of beer. By understanding the differences between lager yeast and ale yeast, and by controlling the fermentation temperature and pitching rate, brewers can produce high-quality, delicious lager beer with a crisp, clean flavor and smooth finish.

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