Beer is an alcoholic beverage that is made from cereal grains, hops, water, and yeast. Most beers contain from 2 to 6 per cent alcohol. People throughout the world drink about 30 billion gallons (114 billion liters) of beer annually.

To make beer, brewers mix barley malt with water and such grains as corn and rice. This mixture is heated to convert starches in the grains into sugar and other carbohydrates (substances composed of carbon, hydrogen, and oxygen). The grain is removed from the mixture, which is then boiled with hops to provide more flavor. Next, brewers add yeast, which starts a process called fermentation. This process changes the sugar into alcohol. After fermentation, the beer is aged for several weeks or months to improve its taste. It is then filtered and packaged.

Beer includes such food substances as carbohydrates, proteins, and vitamins and minerals. A 12-ounce (355-milliliter) serving of most beers made in the United States contains from 140 to 150 calories.

The word beer is commonly used as the general term for all alcoholic malt beverages. There are two general types of beer--lager and ale--and they are made by different fermentation processes.

The most popular beer in the United States is lager beer, known for its effervescence (bubbly quality) and its balanced hop and malt flavors. Light beer is a kind of lager that is specially brewed to reduce the carbohydrates and calories in it. Pilsner is also a lager beer, but it has a stronger hops flavor than regular lager. Dry beer is a lager that tastes less sweet than other lagers. Bock beer, another lager, is a heavy beer with a higher alcoholic content than regular lager. Ale has a distinctive hop flavor and aroma. Porter and stout are dark ales with a strong and bitter taste. Malt liquor is a term for lagers and ales with a higher alcoholic content than regular beers.

Beer is one of the oldest kinds of alcoholic drinks. Beer was brewed at least as early as 4000 B.C. The ancient Assyrians, Babylonians, Chinese, Egyptians, Greeks, Romans, and Teutons all made beer.

Brewing is the process used to make such alcoholic malt beverages as lager beer and ale. The chief ingredients used in brewing are barley malt and other cereal grains, as well as hops, yeast, and water. In the part of the brewing process called fermentation, the yeast converts the sugar obtained from the grains into alcohol. Most beers contain from 2 to 6 percent alcohol.

All brewers use the same basic brewing process. This article describes the basic process, which consists of six major steps: (1) malting, (2) mashing, (3) boiling, (4) fermentation, (5) aging, and (6) finishing.

Malting produces certain chemical and physical changes in barley, the chief grain used in making most beers. Barley malt contains starch and protein, as well as enzymes that are essential to the brewing process. Malt provides much of the flavor in beer.

To produce barley malt, brewers soak the barley in water from one to several days to increase its moisture content to the desired level. The barley is then placed in special chambers where it is allowed to germinate (sprout) for several days. Next, the barley is moved to large ovens called kilns, where it is dried and the germination process is halted. Brewers start the drying process at a low temperature and gradually increase the heat to 180 °F (82 °C). They then remove the sprouts and store the grain, now called malt, for a minimum of 4 weeks.

Mashing. Brewers grind the barley malt and mix it with water to form a mash. They also make a mash of other cereal grains, such as corn and rice. The mashes are combined and heated to about 155 °F (68 °C). During the heating process, enzymes in the malt liquefy the grain and convert the starch to sugar and other, more complex carbohydrates (substances composed of carbon, hydrogen, and oxygen). The mixture is filtered to remove grain kernels. The remaining amber liquid, called wort, is transferred to large kettles for boiling.

Boiling. During the boiling process, dried blossoms of the hop plant are added to the wort. The hops prevent spoilage and add aroma and flavor to the brew. After boiling, brewers clarify and cool the wort.

Fermentation. To promote fermentation, brewers add yeast to the wort. Yeast converts the sugar in the wort into alcohol and carbon dioxide. Brewers remove the carbon dioxide and store it for various uses in the brewery. Fermentation takes about a week. After fermentation, most of the yeast is removed from the brew.

Aging improves the taste of beer. Brewers age beer in storage tanks for several weeks or months. Some brewers age beer by fermenting it a second time.

Finishing. After the beer has been aged, brewers further clarify and filter it several times to remove the remaining yeast. The beer is then packaged in bottles, cans, or stainless steel kegs. Most bottled or canned beer is pasteurized before being packaged.

History. Brewing was developed more than 6,000 years ago. Several ancient peoples, including the Babylonians and Inca, brewed beer. Large-scale commercial brewing began in Germany in the A.D. 1100's. A brewery established in 1632 in New Amsterdam (now New York City) was probably the first brewery in North America. Today the United States produces about 51/2 billion gallons (21 million liters) of alcoholic malt beverages annually.