Ales and lagers are the two main varieties of beer, although each is divided into several subcategories. There are several differences between ale and lager, both in taste and in the fermentation process. Although it is often suggested, the differences between ales and lagers do not involve color or alcohol content.
One of the most frequently cited distinctions that separate ales and lagers is the variety of yeast used to ferment the brew. With a few exceptions, ale uses a top-fermenting yeast that rises to the top of the mixture. Lagers use a bottom-fermenting yeast that forms at the bottom of the brewing vessel and can even be reused. The placement of the yeast does not directly alter flavor, but it changes the level of temperature necessary for fermentation.
Bottom-fermenting yeasts in lager necessitate a cooler temperature and longer fermentation time. Most lagers ferment at a temperature between 52-58 degrees° F (11-14° degrees C,) often leading to increased sulfur production. The lower temperature necessitates a longer brewing time, much longer than that of a typical ale. With the long brewing process, the sulfur flavors integrate into the lager, creating a crisp, clean flavor.
For ale production, top-fermenting yeasts work best at a higher temperature, between 64-70° F (17-21° C.) The warmer level allows flavorful esters to form in the yeast, leading to fruity, full-bodied flavors and aromas. Usually, top-fermenting yeasts will not produce at lower temperatures, needing the warmth to increase yeast activity.
The yeast and temperature differences lead to some distinctions between ideal ales and lagers. While ales are meant to have a complex, multi-layered taste, lagers are judged according to the strength of their main flavor. This distinction is usually referred to as complexity versus angularity.
Ales also tend to have more additional flavors, due to their experiments with complex tastes. In 1516, a German law called Reinheitsgebot was passed that limited the allowed ingredients in beer to water, barley, and hops. Although the law is no longer in effect, most German breweries, which usually produce more lagers than ales, still conform to some of the rules.
There are some similarities between ales and lagers, although modern variations provide many exceptions. Generally, their alcohol content is similar, usually between 3-10%. The bitterness is not determined by yeast fermentation or temperature, but rather by the variety of ingredients used in the brewing process. Color can also be similar, with light, medium, and dark varieties of both ale and lager available.
Both ales and lagers have a variety of sub-classes, based on color, taste, and character. Common ale varieties include pale ale, amber ale, porter, and stout. There are fewer versions of lager, but commonly found types include pilsner, dunkel, and doppelbock.
Whether you prefer lager or ale is a matter of personal taste, as the two are not really comparable to one another. To discover what your preferences are, try visiting a microbrewery where they provide tasting sets. By trying a variety of both ales and lagers, you will be able to distinguish the unique characteristics of both types of beer, and help understand your own preferences in terms of taste and depth.