The essentials of good brewing #7: conditioning and racking (or packing)

Last time round we looked at fermentation. Once fermented, the 'green' beer is poured off into a conditioning vessel ('CV') where it matures and there is further settling of yeast. 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 or cask ales), the beer can go directly into the cask, barrel or bottle. More hops may be added to the cask (dry hopping) for extra aroma. Finings (traditionally made from the swim bladders of certain fish) 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 secondary 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 pasteurised to guard against deterioration from microbes. Sometimes known as 'bright beer', they reach the consumer in kegs, bottles or cans. For lagers there is a longer period of conditioning in the brewery at low temperature. The word lager comes from the German word lagern - to store at a cold temperature.