It all comes down to fermentation.   

By Corey Williams
August 05, 2019
izusek/Getty Images

Every beer in the world has four ingredients in common: water, grain, yeast, and hops. Most of those beers can be sorted into two broad categories: ales and lagers. But what makes an ale an ale, and what makes a lager a lager? It all comes down to differences in the fermentation process.

Ale vs. Lager

Ales are typically robust and aromatic. They’re served warmer than lagers (40 to 55 degrees Fahrenheit, depending on the type of ale) and tend to have a somewhat bitter taste.

The history of ale goes back thousands of years. It seems crazy now, but ale was actually one of the most important sources of nutrition for people in the Middle Ages. Grains made up a huge portion of medieval diets, and ale was one of the three most important sources of grains, along with soups and breads.

Lagers, which have Bavarian origins, are much newer, dating to the 19th century. After the invention of artificial cooling, brewers were able to store beer in cool conditions despite outside temperatures.

Lagers are served at around 38 to 45 degrees Fahrenheit and usually taste lighter than ales. They're highly carbonated and have a crisp, smooth, and clean taste.

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Yeast

Ale is fermented using a very common yeast called Saccharomyces cerevisia, which is also used for wine and bread making. Saccharomyces cerevisia is a top-fermenting yeast, meaning it rises to the top before sinking to the bottom as fermentation is ending. Top-fermenting yeasts yield more flavor, according to VinePair.

Lagers are fermented using a yeast called Saccharomyces pastorianus, which does not rise to the top as before settling to the bottom as fermentation ends. Bottom-fermented lagers ferment at a low temperature for a longer time, resulting in a crisper beer.

Fermenting Temperature

Ales typically ferment best between 60 and 75 degrees, while lagers are fermented between 45 and 55 degrees.

Lager was originally brewed in European caves, where the temperature was cool. The cold temperatures meant the beer would be kept for a longer period of time than ale.

The cool storage results in a brew with better clarity and more delicate flavors.

Types of Ales

Types of ales you might be familiar with are pale ales, India pale ales (IPAs), porters, and stouts. Some of the most popular ale brands include Newcastle, Sierra Nevada, Founder’s, and Guiness.

Types of Lagers

Lagers can be separated into two categories: pale (Helles, Pilsner, Märzen, bock) and dark (Dunkel, doppelbock, schwarzbier). Even if you’re a casual beer drinker, you’re probably familiar with the brands Miller, Budweiser, PBR, and Coors, which are all types of pale lagers.

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