Brewery

A brewery is a facility that produces beer. Typically a brewery is divided into distinct sections, with each section reserved for one part of the brewing process. Breweries can take up multiple city blocks, or be a collection of equipment in a homebrewer's kitchen. The diversity of size in breweries is matched by the diversity of processes, degrees of automation, and kinds of beer used in breweries.

History

The oldest brewery in the world still in operation is believed to be the Bavarian State-owned brewery Weihenstephan, found in the German city of the same name, which can trace its history back to 1040.

The industrialization of the brewery

Beer, in some form, can be traced back almost 5000 years to Mesopotamian writings describing daily rationings 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 storeys, with equipment on higher floors utilized earlier in the production process, so that gravity could assist with the transfer of product from one stage to the next. This layout is often 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 breweries are made of stainless steel.

Major technological advances

A handful of major breakthroughs have lead to the modern brewery and its ability to produce the same beer consistently.

The steam engine, vastly improved in 1765 by James Watt, brought automatic stirring mechanisms, and pumps into the brewery. It gave brewers the ability to more reliably mix liquids 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 several other people, 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 was 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.

Most importantly, 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 lead 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 still rely on "spontaneous" fermentation for their beers.

The modern brewery

Breweries today are made predominantly of stainless steel, although vessels often have a decorative copper clading for a nostalgic look. Stainless steel has many favorable characteristics which 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 (concentraited cholorine 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 vaccum will be formed incidentally during cleaning.

Heating in the brewhouse is usually achieved through pressurized steam, although direct-fire systems are not unusual in small breweries. Similarly, cooling in other areas of the brewery is typically done by cooling jackets on tanks, which allow the brewer to precicely control 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 analyized in order to correct for variations; Samples are pulled at almost every step and tested for oxygen content, unwanted microbial infections, and other beer-aging compounds; and a representitive sample of the finished product is often stored for months for comparison when complains are filed.

The Brewing Process

Work in the brewery is typically divided into 7 steps: Mashing, Lautering, Boiling, Fermenting, Conditioning, Filtering, and Filling.

Mashing

Temp	Enzyme	Digests
40°C	Glucanase	β-Glucan
50°C	Protease	Protein
62°C	β-Amylase	Starch
72°C	α-Amylase	Starch

Mashing is the process of mixing milled grain (typically malted grain) with water, and heating this mixture up with rests at certain temperatures to allow enzymes in the malt to break down the starch in the grain into sugars, typically maltose.

Large breweries usually employ a decoction mash method, in which part of the mash is boiled to extract more starch from the grain, then returned to the mash to achieve the next rest temperature. These can be classified into one-, two-, and three-step decoctions, depending on how many times part of the mash is drawn off to be boiled. Smaller breweries use infusion mashing, in which the mash is heated directly to go from rest temperature to rest temperature. Some infusion mashes acheive temperature changes by adding hot water, and there are also breweries that do single-step infusion, performing only one rest before lautering. It is important to note that fancy equipment and methods do not guarantee a good beer. Many wonderful beers are produced on inexpensive, bare-bones equipment, and some bad beers are produced in breweries that are state-of-the-art.

In large breweries, in which optimal utilization of the brewery equipment is economically necessary, there is at least one dedicated vessel for mashing. In decoction processes there must be at least two. The vessel is has a good stirring mechanism to keep the temperature of the mash uniform, and a heating device which is efficent, and will not scorch the malt. Smaller breweries often use the boil kettle for mashing, or use the lauter tun. The latter case either limits the brewer to single-step infusion mashing, or leaves the brewer with a lauter tun which is not completely appropriate for the lautering process.

Grain milling

The grain used for making beer must first be milled. Milling increases the surface area of the grain, making the starch more accessible, and separates the seed from the husk. Care must be taken when milling to ensure that the starch reserves are sufficently milled without damaging the husk and providing coarse enough grits that a good filter bed can be formed during lautering.

Grains are typically dry milled. Dry mills come in four varieties: two-, four-, five-, and six-roller mills. Hammer mills, which produce a very fine mash, are often used when mash filters are going to be employed in the Lautering process because the grain does not have to form its own filterbed. In modern plants, the grain is often conditioned with water before it is milled to make the husk more pliable, thus reducing breakage and improving lauter speed.

Two-roller mills

Two-roller mills are the simplest variety, in which the grain is crushed between two rollers before it continues on to the mash tun. The spacing between these two rollers can be adjusted by the operator. Thinner spacing usually leads to better extraction, but breaks more husk and leads to a longer lauter.

Four-roller mills

Four-roller mills have two sets of rollers. The grain first goes through rollers with a rather wide gap, which separates the seed from the husk without much damage to the husk, but leaves large grits. Flour is sieved out of the cracked grain, and then the coarse grist and husks are sent through the second set of rollers, which further crush the grist without damaging the crusts. There are three-roller mills, in which one of the rollers is used twice, but they are not recognized by the German brewing industry.

Five- and Six-roller mills

Six-roller mills have three sets of rollers. The first roller crushes the whole kernel, and its output is divided three ways: flour immediately is sent out the mill, grits without a hust proceed to the last roller, and husk, possibly still containing parts of the seed, go to the second set of rollers. From the second roller flour is directly output, are are husks and any possible seed still in them, and the husk-free grits are channeled into the last roller. Five-roller mills are basically six-roller mills in which one of the rollers performs double-duty.

Mashing-in

Mixing of the strike water, water used for mashing in, and milled grist must be done in a such a way as to minimize clumping and oxygen uptake. Traditionally this was done by first adding water to the mash vessel, and then introducing the grist from the top of the vessel in a thin stream. This unfortunately led to a lot of oxygen absorption, and loss of flour dust to the surrounding air. A premasher, which mixes the grist with mash-in temperature water while it is still in the delivery tube, reduces oxygen uptake and prevents dust from being lost.

Mashing in is typically done between 35 °C and 45 °C, but for single-step infusion mashes mashing in must be done between 62 °C and 67 °C for amylases to break down the grain's starch into sugars. The weight-to-weight ratio of strike water and grain varies from 1:2 for dark beers in single-step infusions to 1:4 or even 1:5, ratios more suitable for light-colored beers and decoction mashing, where much mash water is boiled off.

Lautering

Lautering is the separation of the extracts won during mashing from the remains of the spent grain. It is acheived 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.

Boiling

Boiling the won extracts, called wort ensures its sterility, and thus prevents a lot of infections. During the boil hops are added, which contribute their bitter aromas and flavor compounds to the beer, and, along with the heat of the boil, causes proteins in the wort to coagulate and the pH of the wort to fall.

Fermenting

Fermentation, as a step in the brewing process, starts 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 sugars won from the malt are metabolized into alcohol and carbon dioxide.

Conditioning

Conditioning starts when the yeast has eaten almost all the sugar in the beer. During conditioning the beer is typically cooled from its fermentation temperature to around freezing. This deactivates the yeast, and also causes some unwanted flavors to fall out of the beer and lead to a smoother flavor.

Filtering

Filtering the beer stabilizes the flavor, and gives beer its polished shine and brilliance. Not all beer is filtered. When tax determination is required by local laws, it is typically done at this stage in offically-callibrated tank.

Packaging

Packaging is putting the beer into the containers in which it will leave the brewery. Typically this means in bottles and kegs, but it might include bulk tanks for high-volume customers.