What type of yeast is primarily used in the fermentation of ales?

The primary yeast used in the fermentation of ales is Saccharomyces cerevisiae. This species of yeast is known for its ability to ferment at warmer temperatures, typically between 60°F to 75°F (15°C to 24°C), which is characteristic of ale production. Saccharomyces cerevisiae is a top-fermenting yeast, which means it rises to the top of the fermentation vessel during fermentation, allowing for the production of a wide variety of ale styles with distinct flavors and aromas.

In contrast, other options represent different yeast types or species that have different fermentation characteristics. For example, Saccharomyces pastorianus is primarily used in lager production and ferments at cooler temperatures, typically below 50°F (10°C). Brettanomyces is a wild yeast known for contributing unique flavors and aromas, often used in certain specialty beers or sour ales, rather than standard ale production. Kluyveromyces is not typically used for brewing ales but is instead known for its role in dairy fermentation and other applications.

Understanding these distinctions helps in identifying the fermentation processes and flavors associated with different beer styles.