Beer

Beer is the world's oldest and most popular alcoholic beverage. It is produced through the fermentation of starch based material, commonly cereal, though cassava root in Africa, potato in Brazil and agave in Mexico, among other starch sources, have been used.

Neither the alcoholic beverages made from the fermentation of sugars derived from non-starch sources (e.g., grape juice or honey), nor the beverages distilled after fermentation are considered beer.

Because the ingredients and procedures used to make beer can differ, beer characteristics such as taste and colour may also vary. While local names for beers made with the same methods and ingredients may vary, the similarities of method and ingredients can be detected to form a study of the nature of beer styles.

History

Beer is one of the oldest beverages humans have produced, dating back to at least the 5th millennium BC and recorded in the written history of Ancient Egypt and Mesopotamia. As almost any substance containing carbohydrates, namely sugar or starch, can naturally undergo fermentation, it is likely that beer-like beverages were independently invented among various cultures throughout the world.

Beer largely remained a homemaker's activity, made in the home in medieval times. By the 14th and 15th centuries, beermaking was gradually changing from a family-oriented activity to an artisan one, with pubs and monasteries brewing their own beer for mass consumption.

Today, the brewing industry is a huge global business, consisting of several multinational companies, and many thousands of smaller producers ranging from brewpubs to regional breweries.

The brewing process

Though the process of brewing beer is complex and varies considerably, the basic stages that are consistent are outlined below. There may be additional filtration steps between stages.

Mashing: The first phase of brewing, in which the malted grains are crushed and soaked in warm water in order to create a malt extract. The mash is held at constant temperature long enough for enzymes to convert starches into fermentable sugars.
Sparging: Water is filtered through the mash to dissolve the sugars. The darker, sugar-heavy liquid is called the wort.
Boiling: The wort is boiled along with any remaining ingredients (excluding yeast), to remove excess water and kill any microorganisms. The hops (whole, pelleted, or extract) are added at some stage during the boil.
Fermentation: The yeast is added (or "pitched") and the beer is left to ferment. After primary fermentation, the beer may be allowed a second fermentation, which allows further settling of yeast and other particulate matter "trub" which may have been introduced earlier in the process. Some brewers may skip the secondary fermentation and simply filter off the yeast.
Packaging: At this point, the beer contains alcohol, but not much carbon dioxide. The brewer has a few options to increase carbon dioxide levels. The most common approach by large-scale brewers is force carbonation, via the direct addition of CO2 gas to the keg or bottle. Smaller-scale or more classically-minded brewers will add extra ("priming") sugar or a small amount of newly fermenting wort ("kräusen") to the final vessel, resulting in a short refermentation known as "cask-" or "bottle conditioning".
After brewing, the beer is usually a finished product. At this point the beer is kegged, casked, bottled, or canned.

Unfiltered beers may be stored for further fermentation in conditioning tanks, casks or bottles to allow smoothing of harsh alcohol notes, integration of heavy hop flavours, and/or the introduction of oxidised notes such as wine or sherry flavours. Some beer enthusiasts consider a long conditioning period attractive for various strong beers such as Barley wines. There are some beer cafes in Europe, such as Kulminator in Antwerp, which stock beers aged ten years or more. Aged beers such as Bass Kings Ale from 1902, Courage Imperial Russian Stout and Thomas Hardys Ale are particularly valued.

Ingredients
 
The main ingredients of beer are water, malted barley, hops and yeast. Other ingredients, such as flavouring or sources of sugar, are called adjuncts and are commonly used; common adjuncts are corn, rice and sugar. These starches convert in the mashing process to easily fermentable sugars that serve to increase the alcohol content of beer while adding little body or flavor. Major American breweries use relatively high percentages of adjuncts in order to produce very light-bodied beer at 4-5% alcohol by volume.

Water: Because beer is composed mainly of water, the source of the water and its characteristics have an important effect on the character of the beer. Many beer styles were influenced or even determined by the characteristics of the water in the region. Although the effect of, and interactions between, various dissolved minerals in brewing water is complex, as a general rule, hard water is more suited to dark styles such as stouts or porters, while very soft water is more suited for brewing light-colored beers, such as pilsners.

Malt: Among malts, barley malt is the most widely used owing to its high amylase content, a digestive enzyme which facilitates the breakdown of the starch into sugars. However, depending on what can be cultivated locally, other malted and unmalted grains are also commonly used, including wheat, rice, oats, and rye, and less frequently, maize and sorghum. Malt is formed from grain by soaking it in water, allowing it to start to germinate, and then drying the germinated grain in a kiln. Malting the grain produces the enzymes that will eventually convert the starches in the grain into fermentable sugars. Different roasting times and temperatures are used to produce different colors of malt from the same grain. Darker malts will produce darker beers. In most cases, two or more types of malt are combined when making modern beers.

Hops: Hops have commonly been used as a bittering agent in beer since the seventeenth century. Hops contain several characteristics very favourable to beer: (a) hops contribute a bitterness that balances the sweetness of the malt, (b) hops also contribute aromas which range from flowery to citrus to herbal, (c) hops have an antibiotic effect that favours the activity of brewer's yeast over less desirable microorganisms and (d) the use of hops aids in "head retention", the length of time that foamy head created by the beer's carbonation agent will last. The bitterness of commercially-brewed beers is measured on the International Bitterness Units scale. While hops plants are grown by farmers all around the world in many different varieties, there is no major commercial use for hops other than in beer.

Yeast: is a microorganism that is responsible for fermentation. A specific strain of yeast is chosen depending on the type of beer being produced, the two main strains being ale yeast (saccharomyces cerevisiae) and lager yeast (saccharomyces uvarum), with some other variations available, such as brettanomyces and Torulaspora delbrueckii. Yeast will metabolise the sugars extracted from the grains, and produce alcohol and carbon dioxide as a result. Before yeast's functions were understood, all fermentations were conducted naturally using wild or airborne yeasts; although a few styles such as lambics still rely on this ancient method, most modern fermentations are conducted using pure yeast cultures. On average, beer's alcohol content is between 4% and 6% alcohol by volume, although it can be as low as 2% and as high as 14% under ordinary circumstances and several brewers claim to make beers that are upwards of 20%.

Clarifying agent: Some brewers add one or more clarifying agents to beer that are not required to be published as ingredients. Common examples of these include Isinglass finings, obtained from swimbladders of fish; kappa carrageenan, derived from seaweed; Irish moss, a type of red alga; and gelatin. Since these ingredients may be derived from animals, those concerned with the use or consumption of animal products should obtain specific details of the filtration process from the brewer.