Cask ale

Cask ale is brewed in the same manner as keg beer. The same brew run could be used to make cask, keg and bottled beer. The difference is what happens after the primary fermentation is finished and the beer has been left to condition. While pasteurised keg and bottled beers are then subjected to filtering and flash heating, the beer for the cask is simply placed in the cask in its natural state. Finings, such as isinglass (the swim bladder of fish) or Irish Moss (a seaweed), are placed in the cask to drag down the yeast and clear the beer. Extra hops and sugar may also be added. The cask is sealed and sent off to the pub. In this state it is like a bottle conditioned beer, and like bottle conditioned beers the beer will continue to develop for a certain period of time. And like bottle conditioned beers the actual length of time the beer can survive will depend on the nature of the beer itself - strong, dark beers can last for months, light, delicate beers need to be tapped and sold quickly. The landlord will store the casks according to his knowledge of the beer. The delicate beers will be the ones he needs to tap first. The stronger beers will need longer to settle and mature. Some pubs have been known to keep very strong beers in a sealed cask for up to a year to allow them to fully develop.