How a Brewery Works

After malting, barley is milled, which finally removes the hull, breaking it into large pieces. These pieces remain with the grain during the mash, and act as a filter bed during lautering, when sweet wort is separated from insoluble grain material. Other malted and unmalted grains (including wheat, rice, oats, and rye, and less frequently, corn and sorghum) may be used. Some 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.[70]

Hot water (known as "liquor" in brewing terms) is mixed with crushed malt or malts (known as "grist") in a mash tun.[52] 
The mashing process takes around 1 to 2 hours,[53] during which the starches are converted to sugars, 

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. 

The sweet wort collected from sparging is put into a kettle, or "copper" (so-called because these vessels were traditionally made from copper),[56] 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.[57]

During fermentation, the wort becomes beer in a process that requires a week to months depending on the type of yeast and strength of the beer. 

In addition to producing ethanol, fine particulate matter suspended in the wort settles during fermentation. Once fermentation is complete, the yeast also settles, leaving the beer clear.[58]

During fermentation most of the carbon dioxide is allowed to escape through a trap and the beer is left with carbonation of only about one atmosphere of pressure. 

The carbonation is often increased either by transferring the beer to a pressure vessel such as a keg and introducing pressurized carbon dioxide