When it comes to brewing beer, yeast plays a crucial role in the fermentation process. The strain of yeast used can greatly impact the flavor, aroma, and overall character of the beer. The most commonly used yeast strains in the beer-making process come from the Saccharomyces genus, which translates to “sugar fungus” in Latin. This name is quite fitting, as these yeasts have a voracious appetite for sugar.
Within the Saccharomyces genus, there are two main species of yeast that are used in brewing: lager yeast (Saccharomyces pastorianus) and ale yeast (Saccharomyces cerevisiae). These two species have distinct characteristics and are responsible for producing different styles of beer.
Lager yeast, also known as bottom-fermenting yeast, is used in the production of lagers. It is called bottom-fermenting because during fermentation, the yeast settles at the bottom of the fermenter. Lager yeast works best at cooler temperatures, usually between 45-55°F (7-13°C). This yeast ferments more slowly than ale yeast, resulting in a clean and crisp flavor profile. Lagers tend to have a smoother and more subdued taste compared to ales. Some popular lager styles include Pilsners, Bocks, and Märzens.
Ale yeast, on the other hand, is known as top-fermenting yeast because it rises to the top during fermentation. Ale yeast thrives at warmer temperatures, typically between 60-75°F (15-24°C). This yeast ferments more rapidly than lager yeast, which contributes to the fruity and estery flavors often associated with ales. Ales can range from light and refreshing Pale Ales to robust and complex Stouts. The versatility of ale yeast allows for a wide variety of beer styles to be brewed.
Both lager yeast and ale yeast have been used in brewing for centuries and have their own unique history and cultural significance. For example, lager yeast originated in the 15th century in Bavaria, Germany, where brewers discovered that fermenting beer in cold caves resulted in a different flavor profile. This led to the development of the lager style, which became widely popular worldwide.
In my own brewing experiences, I have experimented with both lager yeast and ale yeast to create different styles of beer. I have found that lager yeast produces a clean and crisp taste, perfect for a refreshing summer beer. On the other hand, ale yeast adds complexity and depth to beers, allowing for a wide range of flavors to be explored.
The strain of yeast used in beer greatly influences the final product. Lager yeast and ale yeast, both belonging to the Saccharomyces genus, are the most commonly used yeast strains in brewing. Each yeast has its own characteristics and preferred fermentation temperatures, resulting in distinct flavors and styles of beer. Whether you prefer a smooth and clean lager or a fruity and aromatic ale, yeast is a critical ingredient in the art of brewing.