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A brewery is a dedicated building for the making of beer, though beer can be made at home, and has been for much of beer's history. A company that makes beer is called either a brewery or a brewing company.
The diversity of size in breweries is matched by the diversity of processes, degrees of automation, and kinds of beer produced in breweries. A brewery is typically divided into distinct sections, with each section reserved for one part of the brewing process.
The oldest, still functional, brewery in the world is believed to be the German state-owned Weihenstephan brewery in the city of Freising, Bavaria. It can trace its history back to 1040 AD (this is disputed by the nearby Weltenburg Abbey brewery, who can trace back its beer-brewing tradition to at least 1050 AD, claiming the Weihenstephan document is at least controversial. The Zatec brewery in the Czech Republic claims it can prove that it paid a beer tax in 1004 AD).
Beer, in some form, can be traced back almost 5000 years to Mesopotamian writings describing daily rations of beer and bread to workers. Before the rise of production breweries, the production of beer took place at home and was the domain of women, as baking and brewing were seen as "women's work". Breweries, as production facilities reserved for making beer, did not emerge until monasteries and other Christian institutions started producing beer not only for their own consumption but also to use as payment. This industrialization of brewing shifted the responsibility of making beer to men.
Early breweries were almost always built on multiple stories, with equipment on higher floors used earlier in the production process, so that gravity could assist with the transfer of product from one stage to the next. This layout often is preserved in breweries today, but mechanical pumps allow more flexibility in brewery design.
Early breweries typically used large copper vats in the brewhouse, and fermentation and packaging took place in lined wooden containers. Such breweries were common until the Industrial Revolution, when better materials became available, and scientific advances led to a better understanding of the brewing process. Today, almost all brewery equipment is made of stainless steel.
A handful of major breakthroughs have led to the modern brewery and its ability to produce the same beer consistently.
The steam engine, vastly improved in 1775 by James Watt, brought automatic stirring mechanisms and pumps into the brewery. It gave brewers the ability to mix liquids more reliably while heating, particularly the mash, to prevent scorching, and a quick way to transfer liquid from one container to another. Almost all breweries now use electric-powered stirring mechanisms and pumps. The steam engine also allowed the brewer to make greater quantities of beer, as human power was no longer a limiting factor in moving and stirring.
Carl von Linde, along with others, is credited with developing the refrigeration machine in 1871. Refrigeration allowed beer to be produced year-round, and always at the same temperature. Yeast is very sensitive to temperature, and, if a beer were produced during summer, the yeast would impart unpleasant flavors onto the beer. Most brewers would produce enough beer during winter to last through the summer, and store it in underground cellars, or even caves, to protect it from summer's heat.
The discovery of microbes by Louis Pasteur was instrumental in the control of fermentation. The idea that yeast was a microorganism that worked on wort to produce beer led to the isolation of a single yeast cell by Emil Christian Hansen. Pure yeast cultures allow brewers to pick out yeasts for their fermentation characteristics, including flavor profiles and fermentation ability. Some breweries in Belgium, however, still rely on "spontaneous" fermentation for their beers (see lambic).
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Breweries today are made predominantly of stainless steel, although vessels often have a decorative copper cladding for a nostalgic look. Stainless steel has many favorable characteristics that make it a well-suited material for brewing equipment. It imparts no flavor in beer, it reacts with very few chemicals, which means almost any cleaning solution can be used on it (concentrated chlorine [bleach] being a notable exception) and it is very sturdy. Sturdiness is important, as most tanks in the brewery have positive pressure applied to them as a matter of course, and it is not unusual that a vacuum will be formed incidentally during cleaning.
Heating in the brewhouse usually is achieved through pressurized steam, although direct-fire systems are not unusual in small breweries. Likewise, cooling in other areas of the brewery is typically done by cooling jackets on tanks, which allow the brewer to control precisely the temperature on each tank individually, although whole-room cooling is also common.
Today, modern brewing plants perform myriad analyses on their beers for quality control purposes. Shipments of ingredients are analyzed to correct for variations. Samples are pulled at almost every step and tested for [oxygen] content, unwanted microbial infections, and other beer-aging compounds. A representative sample of the finished product often is stored for months for comparison, when complaints are received.
Brewing is typically divided into 9 steps: milling, malting, mashing, lautering, boiling, fermenting, conditioning, filtering, and filling.
Mashing is the process of mixing milled, usually malted, grain with water, and heating it with rests at certain temperatures to allow enzymes in the malt to break down the starches in the grain into sugars, especially maltose.
Lautering is the separation of the extracts won during mashing from the spent grain to create wort. It is achieved in either a lauter tun, a wide vessel with a false bottom, or a mash filter, a plate-and-frame filter designed for this kind of separation. Lautering has two stages: first wort run-off, during which the extract is separated in an undiluted state from the spent grains, and sparging, in which extract that remains with the grains is rinsed off with hot water.
Boiling the wort ensures its sterility, helping to prevent contamination with undesirable microbes. During the boil, hops are added, which contribute aroma and flavor compounds to the beer, especially their characteristic bitterness. Along with the heat of the boil, they cause proteins in the wort to coagulate and the pH of the wort to fall, and they inhibit the later growth of certain bacteria. Finally, the vapors produced during the boil volatilize off-flavors, including dimethyl sulfide precursors.
The boil must be conducted so that it is even and intense. The boil lasts between 60 and 120 minutes, depending on its intensity, the hop addition schedule, and volume of wort the brewer expects to evaporate.
Fermentation begins as soon as yeast is added to the cooled wort. This is also the point at which the product is first called beer. It is during this stage that fermentable sugars won from the malt (maltose, maltotriose, glucose, fructose and sucrose) are metabolized into alcohol and carbon dioxide. Fermentation tanks come in many shapes and sizes, from enormous cylindroconical vessels that can look like storage silos, to five-gallon glass carboys used by homebrewers.
Most breweries today use cylindroconical vessels (CCVs), which have a conical bottom and a cylindrical top. The cone's aperture is typically around 70°, an angle that will allow the yeast to flow smoothly out through the cone's apex at the end of fermentation, but is not so steep as to take up too much vertical space. CCVs can handle both fermenting and conditioning in the same tank. At the end of fermentation, the yeast and other solids have fallen to the cone's apex can be simply flushed out through a port at the apex.
Open fermentation vessels are also used, often for show in brewpubs, and in Europe in wheat beer fermentation. These vessels have no tops, making it easy to harvest top-fermenting yeasts. The open tops of the vessels increase the risk of contamination, but proper cleaning procedures help to control the risk.
Fermentation tanks are typically made of stainless steel. Simple cylindrical tanks with beveled ends are arranged vertically, and conditioning tanks are usually laid out horizontally. A very few breweries still use wooden vats for fermentation but wood is difficult to keep clean and infection-free and must be repitched often, perhaps yearly.
After high kräusen, the point at which fermentation is most active and copious foam is produced, a valve known in German as the spundapparat may be put on the tanks to allow the carbon dioxide produced by the yeast to naturally carbonate the beer. This bung device can regulate the pressure to produce different types of beer; greater pressure produces a more carbonated beer.
When the sugars in the fermenting beer have been almost completely digested, the fermentation process slows and the yeast cells begin to die and settle at the bottom of the tank. At this stage, especially if the beer is cooled to around freezing, most of the remaining live yeast cells will quickly become dormant and settle, along with the heavier protein chains, due simply to gravity and molecular dehydration.
Conditioning can occur in fermentation tanks with cooling jackets. If the whole fermentation cellar is cooled, conditioning must be done in separate tanks in a separate cellar.
Some beers are conditioned only lightly, or not at all. An active yeast culture from an on-going batch may be added to the next boil after a slight chilling in order to produce fresh and highly palatable beer in mass quantity.
Filtering the beer stabilizes flavor and gives it a polished, shiny look. It is an optional process. Many craft brewers simply remove the coagulated and settled solids and forgo active filtration.
In localities where a tax assessment is collected by government pursuant to local laws, any additional filtration may be done using an active filtering system, the filtered product finally passing into a calibrated vessel for measurement just after any cold conditioning and prior to final packaging.
Filters come in many types. Many use pre-made filtration media such as sheets or candles. Kieselguhr, a fine powder of diatomaceous earth, can be introduced into the beer and circulated through screens to form a filtration bed. Filtration ratings are divided into rough, fine, and sterile. Rough filters remove yeasts and other solids, leaving some cloudiness, while finer filters can remove body and color. Sterile filters remove almost all microorganisms.
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Brewing companies range widely in the volume and variety of beer produced, ranging from small breweries, such as Ringwood Brewery, to massive multinational conglomerates, like SABMiller in London or Anheuser-Busch InBev, that produce hundreds of millions of barrels annually. The biggest brewer in the world is the Belgian-Brazilian company Anheuser-Busch InBev. Some commonly used descriptions of breweries are:
In 2012 the four largest brewing companies controlled 50% of the market