Which yeast type is commonly referred to as "lager yeast"?

The yeast type commonly referred to as "lager yeast" is Saccharomyces pastorianus. This yeast is specifically used for fermenting lagers, which are characterized by a clean, crisp taste and typically undergo fermentation at lower temperatures compared to ales. Saccharomyces pastorianus functions optimally in cooler conditions, which is essential in the lagering process, allowing for slower fermentation and the development of subtle flavors.

In contrast, Saccharomyces cerevisiae, known as ale yeast, ferments at warmer temperatures and is responsible for the production of ales. Brettanomyces is a wild yeast known for its contribution to certain styles of beer, particularly those that are funky or sour, and is not primarily used for lagers. Meanwhile, champagne yeast is a specific strain of Saccharomyces that is used in the production of sparkling wines and is not associated with lager production. Understanding the characteristics and fermentation profiles of these different yeast types is crucial for brewing various beer styles effectively.