Brewing

views updated

Brewing

Brewing is a multi-stage process during which the brewer encourages a grain such as barley to germinate briefly, steeps the grain in water to release its sugars, and adds yeast to the mixture, which ferments the sugar, turning it into alcohol and carbon dioxide . Around the world, people have brewed grains and starchy vegetables for thousands of years from ingredients as varied as rice , corn, cassava, pumpkins, sorghum , and millet, and brewed beverages are staples in the diets of many cultures.

History

Archaeologists have turned up evidence that the Sumerian people in the Middle East were brewing barley as long as 8,000 years ago. These early brewers may have discovered the fundamental processes of brewing as they observed—or tasted—what happened when they left fruit juices or cereal extracts exposed to the wild yeasts that naturally float in the air. Native Americans made a beer from corn, which they softened by chewing and mixing into a pulpy mass with saliva. They then set this masticated corn out in a vessel to ferment, and enjoyed the resulting drink.

Throughout Europe , breweries sprang up where there was good water for brewing. During the Middle Ages, monasteries became the centers for brewing, and the monks originated brewing techniques and created many of the beers still popular today. Early European settlers in North America brought with them from Europe a taste for beer, but followed the Native Americans' example and initially made beer from corn and pumpkins, which they flavored with such local additives as the tops of spruce trees.

With the spread of the British empire and rise of industrialization over the past 150 years, traditional European beer began to move from its local markets to towns, pubs, and countries far away from its place of origin. This emigration was aided with the introduction of bottled beer in 1875 by the Joseph Schlitz Brewing Company in Milwaukee, Wisconsin, and the later advent of canned beer in the 1930s.

Brewing process

The brewer's first step in making a beer is to wet the kernels of grain, promoting their germination , or sprouting. During this process, the germ or embryo of the grain breaks down slightly, releasing the enzymes that turn starches, complex sugars, into simple sugars. The brewer allows the grain to germinate for a short period and dries it quickly in a kiln. Dried, malted grain is very durable and easily stored.

The brewer next mixes the dried malt with water to create a porridgy substance called mash. During this phase, the mash is brought to a temperature of around 150°F (66°C) and is kept there a number of hours. The starchy components of the grain break down during mashing, and are converted into simple sugars, which yeast will be able to digest during the fermentation phase.

The brewer now adds more water to the mash and rinses out a watery sugar solution called wort, which is heated to a boil. At this point, the brewer adds hops, the flower of the Humulus lupulus vine, which give beer its characteristic bitter flavor and aroma.

When the wort has cooled to the temperature most friendly to yeast (50–60°F [10–16°C]), these organisms are added and go to work consuming the sugars in the wort, growing to be as much as five to ten times their original weight. They fuel their growth with the sugar and in the process, change it from carbohydrate to ethanol , a form of alcohol, and carbon dioxide, the gas that is responsible for beer's foam and bubbles.

Types of beer

Most familiar beers are barley-based beverages. In Europe and the United States, beer is usually one of two types, ale or lager. Ale is a traditional British beer that, until the latter part of the nineteenth century, was not flavored with hops. Ale is made with a variety of yeast that rises to the top of the fermentation tank, and that produces a higher alcohol content than lagers. Ales range from pale ales such as Kolsch (from a district around Cologne, Germany) which is strongly hopped and not sweet, to strong, dark, ales such as porter and stout. Lager (which means cellar in German) originated in the Bavarian region of Germany. Lager is made with bottom-fermenting yeast, and is lower in alcohol content than ales. Lagers include: pilsner, a pale beer with a distinctive hop flavor; bock, a strong dark beer; weiss, a pale beer made with wheat that is usually served with slices of lemon or flavored with fruit juices.

Future developments

Current research in brewing technology is focusing on events at the cellular level. For example, brewery researchers are working on methods that will rapidly and accurately detect the presence and identity of unwanted yeasts or other microorganisms that find their way into the beer during brewing, and that change the flavor of the beer. (Potentially problematic organisms include Lactobacillus, Pediococcus, and Obesumbacterium.) Some of the methods already available or soon to be available include those using DNA probes, and protein and chromosome fingerprinting. Some of these techniques are already used in tests designed for at-home pregnancy testing, drug screening, AIDS testing, and tests for the presence of environmental contaminants such as pesticides .

Breweries are also using biotechnological techniques and genetic engineering to select and propagate choice characteristics in barley, rice, corn, yeast, and hops. Some of the characteristics that brewery researchers are working toward include disease resistance in the crops , and in yeast, the ability to resist contamination and to ferment carbohydrates that yeasts have been incapable of fermenting. Micropropagation is a new and experimental technique that involves making any number of genetically identical copies of a plant , by removing minute quantities of its growth points and placing them in a medium that encourages the rapid growth of shoots. This process is then repeated again and again. Mutation breeding is a process for creating mutations, some of which may be desirable, by exposing the plant to x rays or chemical mutagens; and transformation technologies, which allow the breeder to make a change in a single gene by adding or deleting it.

Resources

books

Briggs D.E. and J.S. Hough. Malting and Brewing Science. Volumes 1 & 2. London: Chapman and Hall, 1981.

Gourish and Wilson. The British Brewing Industry, 1830-1980. Cambridge: Cambridge University Press, 1994.

Hough, J.S. Biotechnology of Brewing. Cambridge: Cambridge University Press, 1985.

other

Gump, Barry, ed. Beer and Wine Production: Analyses, Characterization, and Technological Advances. American Chemical Society Symposium Series 536, American Chemical Society, Washington D.C., 1993.

Beth Hanson

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Ale: —A top-fermented beer that, until the latter part of the nineteenth century, was not flavored with hops; traditionally British ale has a higher alcohol content than lagers.
Fermentation: —The process during which yeast consumes the sugars in the wort and releases alcohol and carbon dioxide as byproducts.
Hops: —Comes from the cone of the flower of the vine Humulus lupulus, which is cultivated throughout temperate regions for use in brewing. The addition of hops gives beer its characteristic bitter flavor and aroma.
Lager: —Lager (which means cellar in German) is a traditional Bavarian beer made with bottom-fermenting yeast. These beers are lighter in color and lower in alcohol content than ales. Over the past few decades, lager surpassed ale in popularity.
Malt: —Grain that has germinated, or sprouted, for a short period and is then dried. During germination, the enzymes in the germ of the grain are released, which will make the sugars in the grain available to the yeast.
Wort: —The sugar water solution made when malted barley is steeped in water and its complex sugars break down into simple sugars.
Yeast: —A microorganism of the fungus family that promotes alcoholic fermentation, and is also used as a leavening in baking.