Brewing methods

Brewing is the production of beer through steeping a starch source (commonly cereal grains) in water and then fermenting with yeast. Brewing has taken place since around the 6th millennium BC, and archeological evidence suggests that this technique was used in ancient Egypt. Descriptions of various beer recipes can be found in Sumerian writings, some of the oldest known writing of any sort. Brewing takes place in a brewery by a brewer, and the brewing industry is part of most western economies.

There are several brewing methods, such as barrel aging, double dropping, and Yorshire square.

Barrel aging

Beers are sometimes aged in barrelswhich were previously used for maturing spirits. Lambic beers are aged in wine barrels. Porters and stouts are sometimes aged in bourbon barrels. Goose Island's Bourbon County Stout was one of the first bourbon barrel-aged beers in the U.S., but the method has now spread to other companies, who have also experimented with aging other styles of beer in bourbon barrels (Allagash Brewing Company, for example, makes a tripel aged in discarded Jim Beam barrels.)

By the early twenty-first century, the method of aging beer in used wine barrels had expanded beyond lambic beers to include saison, barleywine, and blonde ale. Commonly, the barrels used for this had previously aged red wine (particularly cabernet sauvignon, merlot, and pinot noir).

Double dropping

Double dropping, more commonly known as the dropping system is a brewing method for the production of ales. During the early 20th century it was the most popular method of fermentation for English ales. It is less commonly used today as it requires additional brewing vessels and a 2-tier brew house. Also, other brewing methods can now emulate these beers without using this brewing method.

During the double dropping process the wort (newly brewed, fermenting beer) is first fermented for a period of time before being 'dropped', under gravity or by other means, into a lower vessel where it continues fermentation. Brakspear's beers are 'dropped' the morning after the day they were brewed - typically about 16 hours later. This process originally took place at the original Brakspear's brewhouse in Henley. Some time later, Brakspear's brewing then moved to Refresh UK's brewery in Witney. A new Brakspear's brewhouse was built to include the original double dropping system.

The dropping process has two primary effects on the beer being fermented. In 'dropping' the newly fermenting beer, 'trub' (dead yeast and excess, staling and haze-forming protein from the malted barley) that has settled during the first period of fermentation will be left behind, leaving a cleaner beer and a cleaner yeast to crop from the beer for the next fermentation.

The second effect of the dropping process is the aeration of the wort, which results in healthy clean yeast growth, and in certain circumstances produces more complex flavors. Brakspear attributes that some of the flavor common to its beers is due to a combination of its very old complex multi-strain yeast and the dropping method which encourages it to produce the butterscotch-flavored compound diacetyl.

Breweries using the double dropping process include Brakspear, who use double dropping for all its regular beers, and Marston's who use double dropping for some of its beers.

Yorkshire Square

The Yorkshire Square fermenting system was perfected well over 200 years ago. Though it has fallen out of favor in modern times due to the amount of time and maintenance it requires, it produces a distinctively flavored beer that is impossible to replicate with other factory methods. For this reason it is now mostly practiced by the smaller, independent breweries which focus on quality, such as Samuel Smith's and Black Sheep.

A Yorkshire Square vessel is a two-story system consisting of a shallow chamber approximately two meters high, above which is a walled deck. Cooled wort, the liquid extracted from malted barley, is fermented by a special yeast in the lower chamber, while the yeasty head settles on the deck above.

During the first stage of fermentation, the fermenting wort is periodically pumped from the bottom of the chamber over the yeasty head, to keep the yeast mixed in with the wort. Later, the mixing is stopped and the wort in the chamber allowed to settle and cool gently.

Most of the yeast rises onto the deck, and is left behind when the beer is drained from the chamber.

The whole process takes at least six days. However, beer straight from a Yorkshire Square vessel will still have a harsh flavor. Before it can be considered drinkable, the residual yeast must be allowed to ferment any remaining sugar, producing a little extra alcohol and carbon dioxide, which mellows the beer and produces a wonderful balance of taste and aroma. This conditioning begins in tanks at the brewery and continues after the beer is filled into casks, hence the phrase 'Cask Conditioned'.

It has been suggested that the Yorkshire square system was developed with the help of Joseph Priestley who, in 1722, delivered a paper to the Royal Society on the absorption of gases in liquids. In addition to being a scientist, and later a political dissident, he was for a time the minister of a Unitarian church in Leeds. During that period he lived next to a brewery on a site that is now the Tetley's brewery.

Historically, the Yorkshire Square vessel was constructed from Yorkshire Sandstone, but Welsh slate quickly proved to be the material of choice. A modern innovation is the so-called 'Round Square' pioneered by the Black Sheep brewery, which is built from stainless steel. The round shape makes it easier to clean out (a task that requires personnel to physically climb in to the vessels) between brewing cycles.