IV.

Beer Characteristics

The two major categories of beer are ales and lagers, and the yeast used in fermentation determines the differences between the two. Ales are fermented with Saccharomyces cerevisiae at warm temperatures for short periods of time, typically a week. This yeast ferments in warmer temperatures to produce a fruity flavor that characterizes ale. Ales are aged, or conditioned, for one to three weeks. Ales should be served at room or cellar temperature—about 13° C (about 55° F).

Lagers are usually drier, crisper, and less fruity in taste than ales. Lagers are fermented with Saccharomyces uvarum at cooler temperatures for longer periods up to two weeks, which encourages the flavor components in lagers to combine and mellow. Lagers are aged for up to 12 weeks. Lagers are best served chilled.

All beer can be further described by three additional variables: color, bitterness, and gravity. Color is determined by the type and amount of malt used to make the beer. For example, lightly roasted malt produces a light-colored beer, while beer made only with barley that has been dark roasted is nearly black in color.

Bitterness depends on the type and amount of grain and hops used in the beer's production. Beers made with wheat, for example, are generally less bitter than beers made with dark-roasted barley. Bittering hops, such as those grown in the Pacific Northwest of the United States, are used to make beers with a more bitter flavor. The mineral content of the brewing water can also accentuate hop bitterness. Beer made with water that has a high level of dissolved minerals is more bitter than beer made with water low in minerals.

Gravity refers to the beer’s density, or the amount of dissolved sugars in the wort. As more sugars dissolve in the brewing water during mashing, the density of the wort increases. The yeast consumes these sugars to produce alcohol during fermentation, so elevated sugar levels translate into a higher alcohol content in the finished beer.