Beer is one of the world's oldest prepared beverages, possibly dating back to the early Neolithic or 9000 BC, and is recorded in the written history of ancient Egypt and Mesopotamia.[8] The earliest Sumerian writings contain references to a type of beer. A prayer to the goddess Ninkasi, known as "The Hymn to Ninkasi", serves as both a prayer as well as a method of remembering the recipe for beer in a culture with few literate people.[5][6] A beer made from rice, which, unlike sake, didn't use the amylolytic process, and was probably prepared for fementation by mastication or malting,[9] was made in China around 7,000 BC.[10]
As almost any substance containing carbohydrates, mainly sugars or starch, can naturally undergo fermentation, it is likely that beer-like beverages were independently invented among various cultures throughout the world. The invention of bread and beer has been argued to be responsible for humanity's ability to develop technology and build civilization.[11][12][13] The earliest known chemical evidence of beer dates to circa 3500–3100 BC from the site of Godin Tepe in the Zagros Mountains of western Iran.[14]
Beer was spread through Europe by Germanic and Celtic tribes as far back as 3000 BC,[15] and it was mainly brewed on a domestic scale.[16] The product that the early Europeans drank might not be recognised as beer by most people today. Alongside the basic starch source, the early European beers might contain fruits, honey, numerous types of plants, spices and other substances such as narcotic herbs.[17] What they did not contain was hops, as that was a later addition first mentioned in Europe around 822 by a Carolingian Abbot[18] and again in 1067 by Abbess Hildegard of Bingen.[19]
Beer produced before the Industrial Revolution continued to be made and sold on a domestic scale, although by the 7th century AD, beer was also being produced and sold by European monasteries. During the Industrial Revolution, the production of beer moved from artisanal manufacture to industrial manufacture, and domestic manufacture ceased to be significant by the end of the 19th century.[20] The development of hydrometers and thermometers changed brewing by allowing the brewer more control of the process and greater knowledge of the results.
Today, the brewing industry is a global business, consisting of several dominant multinational companies and many thousands of smaller producers ranging from brewpubs to regional breweries.[21] As of 2006, more than 133 billion liters (35 billion gallons), the equivalent of a cube 510 metres on a side, of beer are sold per year, producing total global revenues of $294.5 billion (£147.7 billion).[22]
Brewing
The process of making beer is known as brewing. A dedicated building for the making of beer is called a brewery, though beer can be made in the home and has been for much of its history. A company that makes beer is called either a brewery or a brewing company. Beer made on a domestic scale for non-commercial reasons is classed as homebrewing regardless of where it is made, though most homebrewed beer is made in the home. Brewing beer is subject to legislation and taxation in developed countries, which from the late 19th century largely restricted brewing to a commercial operation only. However, the UK government relaxed legislation in 1963, followed by Australia in 1972 and the USA in 1979, allowing homebrewing to become a popular hobby.[23]
The purpose of brewing is to convert the starch source into a sugary liquid called wort and to convert the wort into the alcoholic beverage known as beer in a fermentation process effected by yeast.
Fermenter
The first step, where the wort is prepared by mixing the starch source (normally malted barley) with hot water, is known as "mashing". Hot water (known as "liquor" in brewing terms) is mixed with crushed malt or malts (known as "grist") in a mash tun.[24] The mashing process takes around 1 to 2 hours,[25] during which the starches are converted to sugars, and then the sweet wort is drained off the grains. The grains are now washed in a process known as "sparging". This washing allows the brewer to gather as much of the fermentable liquid from the grains as possible. The process of filtering the spent grain from the wort and sparge water is called wort separation. The traditional process for wort separation is lautering, in which the grain bed itself serves as the filter medium. Some modern breweries prefer the use of filter frames which allow a more finely ground grist.[26] Most modern breweries use a continuous sparge, collecting the original wort and the sparge water together. However, it is possible to collect a second or even third wash with the not quite spent grains as separate batches. Each run would produce a weaker wort and thus a weaker beer. This process is known as second (and third) runnings. Brewing with several runnings is called parti gyle brewing.[27]
The sweet wort collected from sparging is put into a kettle, or "copper", (so called because these vessels were traditionally made from copper)[28] and boiled, usually for about one hour. During boiling, water in the wort evaporates, but the sugars and other components of the wort remain; this allows more efficient use of the starch sources in the beer. Boiling also destroys any remaining enzymes left over from the mashing stage. Hops are added during boiling as a source of bitterness, flavour and aroma. Hops may be added at more than one point during the boil. The longer the hops are boiled, the more bitterness they contribute, but the less hop flavour and aroma remains in the beer.[29]
After boiling, the hopped wort is now cooled, ready for the yeast. In some breweries, the hopped wort may pass through a hopback, which is a small vat filled with hops, to add aromatic hop flavouring and to act as a filter; but usually the hopped wort is simply cooled for the fermenter, where the yeast is added. During fermentation, the wort becomes beer in a process which requires a week to months depending on the type of yeast and strength of the beer. In addition to producing alcohol, fine particulate matter suspended in the wort settles during fermentation. Once fermentation is complete, the yeast also settles, leaving the beer clear.[30]
Fermentation is sometimes carried out in two stages, primary and secondary. Once most of the alcohol has been produced during primary fermentation, the beer is transferred to a new vessel and allowed a period of secondary fermentation. Secondary fermentation is used when the beer requires long storage before packaging or greater clarity.[31] When the beer has fermented, it is packaged either into casks for cask ale or kegs, aluminum cans, or bottles for other sorts of beer.[32]
Ingredients
The basic ingredients of beer are water; a starch source, such as malted barley, able to be fermented (converted into alcohol); a brewer's yeast to produce the fermentation; and a flavouring such as hops.[33] A mixture of starch sources may be used, with a secondary starch source, such as maize (corn), rice or sugar, often being termed an adjunct, especially when used as a lower-cost substitute for malted barley.[34] Less widely used starch sources include millet, sorghum and cassava root in Africa, potato in Brazil, and agave in Mexico, among others.[35] The amount of each starch source in a beer recipe is collectively called the grain bill.
Water
Beer is composed mostly of water. Regions have water with different mineral components; as a result, different regions were originally better suited to making certain types of beer, thus giving them a regional character.[36] For example, Dublin has hard water well suited to making stout, such as Guinness; while Pilzen has soft water well suited to making pale lager, such as Pilsner Urquell.[36] The waters of Burton in England contain gypsum, which benefits making pale ale to such a degree that brewers of pale ales will add gypsum to the local water in a process known as Burtonisation.[37]
Starch source
The starch source in a beer provides the fermentable material and is a key determinant of the strength and flavour of the beer. The most common starch source used in beer is malted grain. Grain is malted by soaking it in water, allowing it to begin germination, and then drying the partially germinated grain in a kiln. Malting grain produces enzymes that convert starches in the grain into fermentable sugars.[38] Different roasting times and temperatures are used to produce different colours of malt from the same grain. Darker malts will produce darker beers.[39]
Nearly all beer includes barley malt as the majority of the starch. This is because of its fibrous husk, which is not only important in the sparging stage of brewing (in which water is washed over the mashed barley grains to form the wort), but also as a rich source of amylase, a digestive enzyme which facilitates conversion of starch into sugars. Other malted and unmalted grains (including wheat, rice, oats, and rye, and less frequently, corn and sorghum) may be used. In recent years, a few brewers have produced gluten-free beer made with sorghum with no barley malt for those who cannot consume gluten-containing grains like wheat, barley, and rye.[40]
Hops
Flavouring beer is the sole major commercial use of hops.[41] The flower of the hop vine is used as a flavouring and preservative agent in nearly all beer made today. The flowers themselves are often called "hops".
Hops were used by monastery breweries, such as Corvey in Westphalia, Germany, from 822 AD,[20][42] though the date normally given for widespread cultivation of hops for use in beer is the thirteenth century.[20][42] Before the thirteenth century, and until the sixteenth century, during which hops took over as the dominant flavouring, beer was flavoured with other plants; for instance, Glechoma hederacea. Combinations of various aromatic herbs, berries, and even ingredients like wormwood would be combined into a mixture known as gruit and used as hops are now used.[43] Some beers today, such as Fraoch' by the Scottish Heather Ales company[44] and Cervoise Lancelot by the French Brasserie-Lancelot company,[45] use plants other than hops for flavouring.
Hops contain several characteristics that brewers desire in beer. Hops contribute a bitterness that balances the sweetness of the malt; the bitterness of beers is measured on the International Bitterness Units scale. Hops contribute floral, citrus, and herbal aromas and flavours to beer. Hops have an antibiotic effect that favours the activity of brewer's yeast over less desirable microorganisms, and hops aids in "head retention",[46][47] the length of time that a foamy head created by carbonation will last. The acidity of hops is a preservative.[48][49]
Yeast
Yeast is the microorganism that is responsible for fermentation in beer. Yeast metabolises the sugars extracted from grains, which produces alcohol and carbon dioxide, and thereby turns wort into beer. In addition to fermenting the beer, yeast influences the character and flavour.[50] The dominant types of yeast used to make beer are ale yeast (Saccharomyces cerevisiae) and lager yeast (Saccharomyces uvarum); their use distinguishes ale and lager.[51] Brettanomyces ferments lambics,[52] and Torulaspora delbrueckii ferments Bavarian weissbier.[53] Before the role of yeast in fermentation was understood, fermentation involved wild or airborne yeasts. A few styles such as lambics rely on this method today, but most modern fermentation adds pure yeast cultures.[54]
Clarifying agent
Some brewers add one or more clarifying agents to beer, which typically precipitate (collect as a solid) out of the beer along with protein solids and are found only in trace amounts in the finished product. This process makes the beer appear bright and clean, rather than the cloudy appearance of ethnic and older styles of beer such as wheat beers.[55]
Examples of clarifying agents include isinglass, obtained from swimbladders of fish; Irish moss, a seaweed; kappa carrageenan, from the seaweed Kappaphycus cottonii; Polyclar (artificial); and gelatin.[56] If a beer is marked "suitable for Vegans", it was clarified either with seaweed or with artificial agents.
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