What’s the Difference Between Ale and Lager

What’s the Difference Between Ale and Lager?

There are a number of misconceptions concerning the differences between ales and lagers. I find most information from homebrewersassociation.com. It is a good website to learn some knowledge.

After all, both ales and lagers can be dark or light, strong or sessionable, hoppy or malty, and so on.
But lagers and ales are different. And the most defining differences have to do with yeast and fermentation.

Yeast

Ales are fermented with Saccharomyces cervisiae, or ale yeast. Ale strains are commonly referred to as “top-fermenting” because the most obvious fermentation activity appears to occur on the surface of the beer, though the term may also reference ale yeast’s tendency to flocculate at the surface (before eventually precipitating out completely to the bottom of the fermenter).
Lagers, on the other hand, are fermented with Saccharomyces pastorianus, which is referred to as a “bottom-fermenting” yeast due to its apparent lack of activity on the surface of fermenting lager beer.

Fermentation Temperature & Duration

Both ale and lager yeasts ultimately do the same thing: convert malt sugars into alcohol and carbon dioxide (CO2). Ale fermentation falls on the warm side of the scale, with yeasts that prefer a general range of 60 to 78°F (16–26°C). Clean fermenting beer styles, like those of English and American “origin” (think pale ales, porters, stouts, etc) tend to stay under 68–70°F (20–21°C).

On the other side of the coin, lagers are fermented at cooler temperatures than ales, but not as cold as you might think. Typically, lager fermentation is conducted in the range of 48–58°F (9–14°C), and because some lager yeasts can ferment more kinds of sugars than ale yeasts, the final beer is often crisper on the palate. The cold fermentation temperature also means that yeast-derived flavors like esters and phenols are rarely present.
Fermenting lager, however, has one additional step compared to ale fermentation: lagering. Many beer drinkers assume lagers are fermented near freezing, but what they are actually thinking of is the extended cold lagering period during which the beer is aged for at least 2 to 3 weeks near 32°F (0°C). This cold aging period allows lager yeasts and other proteins to precipitate out, which helps deliver the signature smooth, crisp lager drinking experience.
Thanks for your reading.

Helen
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