Cicerone Certified Beer Server Practice Exam

The primary difference between ales and lagers lies in the fermentation temperature. Ales are typically fermented at warmer temperatures, ranging from around 60°F to 75°F, using top-fermenting yeast (Saccharomyces cerevisiae). This yeast thrives in warmer environments, leading to a quicker fermentation process and often resulting in a more complex flavor profile due to the production of esters and phenols.

In contrast, lagers are fermented at cooler temperatures, usually between 45°F to 55°F, using bottom-fermenting yeast (Saccharomyces pastorianus). The cooler fermentation process results in a cleaner, crisper taste, as the yeast produces fewer esters and phenolic compounds.

While factors like alcohol content, color, and flavor profile can vary between ales and lagers, they are influenced by the fermentation temperature and yeast used. Therefore, fermentation temperature is the most definitive characteristic that separates these two primary categories of beer.