What is the difference between real ale and keg beer?
Real ale is a living product. It has not been pasteurised or filtered and has undergone a slow secondary fermentation in the vessel (i.e. cask) from which it is served. It is known in the brewing trade as cask conditioned. Keg beer undergoes the same primary fermentation as real ale but after that stage it is filtered and/or pasteurised. No further conditioning can therefore take place. It is known in the brewing trade as ‘brewery-conditioned’ beer. The beer lacks any natural carbonation which would have been produced by the secondary fermentation and so carbon dioxide has to be added artificially. This leads to an over gassy product. Today some keg beers have a mixture of nitrogen and carbon dioxide added; these are known as nitro-keg beers.
