When it comes to brewing beer, the yeast used plays a crucial role in determining the characteristics of the final product. There are two main types of yeast used in beer brewing: ale yeast and lager yeast. These two yeasts have distinct differences in their fermentation process and contribute to the unique flavors and aromas found in different beer styles.
1. Ale Yeast:
Ale yeast, also known as top-fermenting yeast, is the traditional yeast used in brewing ales. Most ale-brewing strains belong to the species Saccharomyces cerevisiae. Ale yeasts ferment at warmer temperatures, typically between 15-24°C (59-75°F), and rise to the top of the fermentation vessel during the process. This top fermentation gives ales their characteristic fruity esters and complex flavors.
– Saccharomyces cerevisiae: This is the most common species of yeast used in brewing ales. It is versatile and can produce a wide range of flavors and aromas, depending on the fermentation conditions. Different strains of S. cerevisiae can result in beers with varying degrees of maltiness, fruitiness, and spiciness.
2. Lager Yeast:
Lager yeast, also known as bottom-fermenting yeast, is used in brewing lagers. The most common species of lager yeast is Saccharomyces pastorianus, which is a hybrid of S. cerevisiae and another yeast species. Lager yeasts ferment at colder temperatures, typically between 7-13°C (45-55°F), and settle at the bottom of the fermentation vessel during the process. This bottom fermentation contributes to the clean, crisp, and smooth characteristics associated with lagers.
– Saccharomyces pastorianus: This yeast species is responsible for the fermentation of lagers. It is known for its ability to ferment at lower temperatures and produce a clean, well-balanced beer with subtle flavors. Lager yeast strains are often selected for their ability to ferment sugars more slowly and efficiently at cooler temperatures.
3. Other Yeast Varieties:
While ale and lager yeasts are the most commonly used in beer brewing, there are other yeast varieties that can be used to create unique beer styles and flavors. Some examples include:
– Brettanomyces: This wild yeast is known for its ability to create complex, funky, and sour flavors in beer. It is often used in the production of Belgian-style lambic, gueuze, and sour beers.
– Kveik: Originating from Norway, kveik yeast is gaining popularity in the craft beer scene. It ferments at high temperatures and produces fruity and spicy flavors. Kveik yeast strains are highly resilient and can ferment beer quickly, making it ideal for homebrewers and commercial breweries alike.
– Wine and Champagne Yeasts: In some cases, wine or champagne yeast strains may be used in beer brewing to create unique characteristics. These yeasts can contribute different flavors and aromas to the beer, similar to what they would do in winemaking.
In my experience as a brewer, I have worked with various yeast strains to create a wide range of beer styles. Each yeast brings its own unique flavors and aromas, allowing for endless possibilities when it comes to beer production. Experimenting with different yeast strains can be a fun and creative process, as it allows brewers to tailor the beer to their desired taste profiles.
It is important to note that while yeast is a crucial factor in beer brewing, other factors such as malt, hops, water, and fermentation conditions also play significant roles in determining the final product. The combination of these elements, along with the choice of yeast, contributes to the vast diversity found in the world of beer.