The following article is reproduced with the kind permission of CAMRA. Sheffield Pub Guide is not endorsed by nor run in conjunction with CAMRA.
All beer is brewed from malted barley, hops, yeast and water, although other ingredients such as fruit, wheat and spices are sometimes used. The yeast turns sugars in the malt into alcohol and the hops provide the bitter flavours in beer and the flowery aroma.
The flavour of the beer depends on many things, including the types of malt and hops used, other ingredients and the yeast variety. Getting the yeast right is essential as each variety has its own distinctive effect on the beer.
In the early 1970s CAMRA coined the term "real ale" to make it easy for people to differentiate between the bland processed beers being pushed by the big brewers and the traditional beers whose very existence was under threat.
Many pubs and brewers use the term "real ale" to describe their beers, but they are also known as cask beers, cask-conditioned ales or even real beer! In pubs the majority of real ales are served using traditional hand-pulls, rather than through modern fonts, but there are some exceptions to this, so if in any doubt, just ask.
Real ale is a natural product brewed using traditional ingredients and left to mature in the cask (container) from which it is served in the pub through a process called secondary fermentation. It is this process that makes real ale unique amongst beers and develops the wonderful tastes and aromas that processed beers can never provide.
There are a huge range of different beer styles, each having its own qualities, tastes and strengths, but falling into one of two main categories; ale or lager. The key difference between ales and lagers is the type of fermentation. Fermentation is the process that turns the fermentable sugars in the malt into alcohol and carbon dioxide. Lagers are made using bottom-fermenting yeast, which sinks to the bottom of the fermenting vessel, and fermentation takes place at a relatively low temperature. Authentic lagers then undergo a long period of cooled conditioning in special tanks. Ales, which includes bitters, milds, stouts, porters, barley wines, golden ales and old ales, use top-fermenting yeast. The yeast forms a thick head on the top of the fermenting vessel and the process is shorter, more vigorous and carried out at higher temperatures than lager. This is the traditional method of brewing British beer.
Real ale is a natural, living product. By its nature this means it has a limited shelf life and needs to be looked after with care in the pub cellar and kept at a certain temperature to enable it to mature and bring out its full flavours for the drinker to enjoy.
Brewery-conditioned, or keg, beer has a longer shelf life as it is not a living product. After the beer has finished fermentation in the brewery and has been conditioned, it is chilled and filtered to remove all the yeast and then it is pasteurised to make it sterile. This is then put in a sealed container, called a keg, ready to be sent to the pub.
The problem is that removing the yeast and "killing off" the product through pasteurisation also removes a great deal of the taste and aroma associated with real ale.
More information about CAMRA and real ale can be found on the following pages: