Beer Fact Friday: Ales vs. Lagers
We tend to get a little technical with these weekly explanations of beer, so for this edition of Beer Fact Friday, let’s get back to basics. Ales and lagers: What’s the difference?
Think of a family tree with offspring branching off in different directions. At the very top: BEER. From there, you get two branches: Ale and Lager. And from those two, you get dozens of branches describing every beer style we currently recognize, from IPA and Stout to Pilsner and Eisbock.
So, all ales and lagers are beers and, barring some rule-breaking hybrids—more on them in a second—every beer you drink is either an ale or a lager. The 100-plus beer styles we know and love today all fall into one of these two categories.
Whether a beer is an ale or a lager is determined by one ingredient and one ingredient alone: the yeast. Here are the big differences between the two yeast types:
- Lager Yeast: Active at cool temperatures (45-55 degrees F). Finishes fermentation more slowly (30+ days). Generally don’t produce flavor compounds in appreciable quantities. Tends to be more active near the bottom of a fermentation tank, which is why it’s sometimes said to be “bottom-fermenting.”
- Ale Yeast: Active at warmer temperatures (60-75 degrees F). Finishes fermentation more quickly (7-14 days). Tends to produce high amounts of flavor compounds such as fruity esters and spicy phenols. Tends to be more active around the top of a fermentation tank, hence the descriptor “top-fermenting.”
To be clear: The only determining factor in whether a beer is an ale or a lager is the yeast strain used to ferment it. While the lagers most folks are familiar with are light, fizzy, and yellow, they don’t *have* to be. Doppelbock, a lager style born in Germany, is among the darkest, heaviest, and highest-ABV beer styles in the world. Likewise, not all ales are heavy and high-octane. Several ale styles—such as American blonde ales and cream ales—are as light in flavor, body, and color as any lawnmower beer.
We mentioned that there were exceptions to the “every beer is either an ale or a lager” rule, and there are a few beer styles that toe the line between the two. California Common—a classic American beer style with which anyone who’s tried Anchor Steam will be familiar—is brewed with lager yeast, but fermented at the low end of acceptable ale yeast temperatures. The German beer style known as Kölsch is the opposite: It’s made with ale yeast, but fermented at lager temps. (Sunbru is one of these, by the way.)