Ale vs Lager, "Not a story about light vs. dark beer."
Beers styles labeled as ale and lager have nothing to do with the color of the beer or its bitterness. It doesn't have anything to do with the alcohol content either. The terms refer to the brewing process and especially the strain of yeast used for fermentation. All beers can be classified as ale or a lager and mostly comes down to the type of yeast used. There are a couple of other differences, but it's the yeast strain used that defines the beer style and impacts the brewing process.
So what are the yeast strains used? Ales are made with top fermenting yeast strains, while lagers are made with bottom fermenting yeasts. In other words, the fermentation takes place in the top or the bottom of the beer tank. The yeast affects the flavor of the ale quite a bit, but the flavor of the lager very little. The top fermenting yeast produces natural chemical compounds that are named esters. The esters create different ale flavors depending on the yeast strain used during beer making. Flavors are often described as spicy, sweet or fruity and full bodied.
The yeast strains used in lager styles ferment in the bottom of the beer making tank and they do not create nearly as much flavor as the ale yeast strains. The fermentation process is much more aggressive in lager making than in ale making. The yeast is the primary difference between the ale and lager beer styles, but there are others. The lager does not get its flavor from yeast fermentation like ale. It is made with more amounts of malts and hops instead. The lager may taste malty and also have more bitterness than ale.
The brewing processes of beer styles are different for ales and lagers. The top fermenting ale yeasts will ferment best around room temperature but no higher than 75 degrees. Since the yeast ferments quickly in ideal warm temperatures, ale fermentation is faster than lager fermentation.
Lager yeast fermentation occurs in colder temperatures ranging from 46 degrees to 59 degrees. It takes longer for lager beers to ferment than ales. The slow fermentation process in lower temperatures produces a crisp mild taste.You will notice that there is nothing about color in this description. The man ordering a beer in the microbrewery thought he was ordering a light beer by ordering ale. He didn’t realize you can order a pale ale, brown ale, scotch ale, Burton ale (dark and strong)... So many beer styles...so little time..! >> Select A Beer Style