The Brewing Process
The first ingredient to come into play is grain (Barley or rice). The seeds go through a chemical and malting process which is at the end milled into a powder called grist or distillers rice.
The grist is transferred to a large vessel called a mash tun, where it is mashed with hot water.
The natural sugars in the malt dissolve in the water and eventually a sweet brown liquid is run off. The wort, as it is called, is then boiled with hops in large vessels, known as coppers.
The next stage is fermentation, the most critical process of all. The hopped wort is cooled and run into fermentation vessels. Yeast is added, and it begins to convert the natural sugars into alcohol, carbon dioxide and a range of subtle flavors.
Ales and stouts are fermented with yeast that rose to the top of the beer. These top fermenting beers develop cloud like, foaming heads. When the yeast has done its job, the head settles into a thick, creamy crust, protecting the beer from air. Ales can also be fermented in closed conical fermenters
Lagers are fermented with a different type of yeast which works at colder temperatures, and which sinks to the bottom of the fermenting vessel. Known as bottom fermentation.
The beer is then separated from the yeast (racked). Once the yeast is removed the beer is passed from fermentation to storage vessels. During transfer the beer is cooled to minus one degree centigrade.
Finally, before a beer leaves the brewery it must be conditioned. The conditioning process differs according to how the beer is to leave the brewery:
For cask conditioned beers (real ales), the beer goes directly into the cask, barrel or bottle. More hops may be added to the cask (dry hopping) for extra aroma. Finings are added which bind the materials responsible for haze and sink to the bottom, clarifying the beer.
The yeast in the beer is still active, and the beer will undergo a second fermentation in the cask, normally in the cellar of a pub. Cask conditioned beer is a delicate product and, just like the beer undergoing fermentation in the brewery, it is vulnerable to attack from all kinds of contamination by wild yeasts and other micro-biological organisms.
Other beers are brought to condition in the brewery, some are fined and filtered and some are pasteurized to guard against deterioration from microbes. For lagers there is a longer period of conditioning in the brewery at low temperature.