A revolutionary new method of storing cask beer in pub cellars could see real ale reaching out to a new audience of drinkers.
Marston's will launch Fast Cask during Cask Ale Week (29 March-5 April) with the aim of attracting thousands of new pubs to real beer.
Fast Cask involves a form of yeast treatment that allows beer to drop bright quickly — the process whereby yeast is cleared from the beer — while still undergoing a secondary fermentation.
It has undergone trials in 70 pubs since November 2009 and there has been no adverse consumer reaction.
Marston's will seek a patent for the yeast "beads" used in the process, but will consider sharing the technology with other brewers.
Finings made from fish bladders will not be needed to clear the beer under Fast Cask — so it will be acceptable to vegans.
Fast Cask the brainchild of Marston's brewing director Richard Westwood, who was asked to tackle the problem that cask beer is not available in 46% of British pubs and bars due to a lack of cellars — or the misplaced belief that real ale is difficult to look after and serve.
Fast Cask, which will initially be used for Marston's Pedigree and Wychwood Hobgoblin, involves removing yeast at the end of primary fermentation and replacing it with "beads" of fresh yeast.
The beads are produced by a process in which fresh yeast solidifies into small beads that act like tiny sponges. The sugars in the beer diffuse into the beads and a secondary fermentation takes place. Marston's is not yet prepared to reveal the process used to produce the beads as patents are pending.
As the beer drops bright almost immediately, it can be served from upright casks that can be moved around at will.
Stephen Oliver, who runs Marston's Beer Company, said it would eradicate the age-old problem of casks being knocked in small, crowded pub cellars followed by a delay of several hours until the beer dropped bright again.
While casks using the system can be still aged in the usual horizontal manner in pub cellars, they can also be stored upright if no cellar exists and the beer has to be kept in small spaces at bar level.
Both Oliver and Westwood stressed that casks must still be tapped and vented to allow them to breathe. But Fast Cask will enable real ale to become available to many more pubs.
They also said pubs serving Marston's cask beers in the traditional manner will continue to be supplied with beer that contains normal yeast cells.
Westwood said the principle of the beads were similar to tea bags. Extensive trials found that the amount of yeast within the beads is within the range usually found in cask beers but they give a more consistent secondary fermentation due to the precise amount of yeast added.