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Robinson's brewery is a family run brewery and is one of the few remaining independent breweries. For over 150 years, the brewery has maintained a reputation for brewing excellence. If you are interested in a guided tour around the brewery, then please telephone (0161) 480 6571 to book your place. Tours last approximately two hours. Because of their popularity though, there is a waiting list - so book well in advance.
The Brewing Process
Mashing
The brewing process starts by grinding the malt in a mill. The grist, as it is then called is mixed or 'mashed' with hot water (liquor) under very carefully controlled conditions of temperature. The resultant mash is collected in a mash tun, a vessel provided with a finely slotted base through which the sugary liquid will subsequently be drawn off. In the mash tun most of the remaining starch in the malt is converted, by the malt's enzymes, to sugar. There is also further breakdown of proteins and, after about an hour, hot water is sprayed on the top, at the same time as the sugary liquid or 'wort' is drained from the bottom. Thus all the goodness or 'extract' is separated from the malt husk, which is left behind in the mash tun as grains which are then sold for cattle feed.
Wort
The next stage is the addition of hops to the wort, together in some brews with additional sugar. The wort is then boiled in large dome shaped vessels called Coppers. The boiling process extracts the bittering resins from the hops, sterilizes the wort and precipitates the residual protein. When the hops have been filtered off in the 'hop back', the wort will be bright and ready for cooling. Up to this point the process at Unicorn Brewery relies largely on gravity, but by now the hot wort is nearly at the bottom of the brewery buiding, so it is pumped up again to large holding tanks, prior to passing through the wort coolers. The cooling plant or 'paraflows' consist of a large number of adjacent stainless steel plates, arranged so that hot wort is running in alternate spaces between the plats. In the intervening spaces, cold water is running in the opposite direction; thus the hot wort emerges cold and cold water emerges hot. It takes just over a barrel of water to cool a barrel of wort and the hot water produced is directed into hot water storage tanks to be used for the next brew. Control equipment is used to adjust the emerging wort temperature to the precise requirements for fermentation. The paraflows are capable of cooling over 5,000 gallons of wort per hour.
Fermentation
The next stage begins the fermentation process. The cold wort is run into large fermenting vessels, into which yeast is 'pitched', whilst maintaining strict temperature control. Over the following 4-7 days the wort is slowly converted to beer as the yeast feeds on the wort sugars, producing alcohol and evolving carbon dioxide in the process. The yeast by this time has multiplied substantially and is now skimmed off the surface. The fermentation process causes a natural temperature rise and on completion the beer is cooled prior to transfer, via road tanker, to storage tanks at the Company's Packaging Centre at Bredbury.
Casking
The final stage in the process is the packaging, into casks for the traditional draught beer or into bottles, cans or kegs. Beers for racking into casks as traditional draught beer are centrifuged in order to regulate the amount of yeast to be added to each cask and are then 'primed' by the addition of a small quantity of sugar. This will later cause the residual yeast in the beer to start fermenting again. It is this secondary fermentation that is responsible for the condition or sparkle in the beer. During the cask racking operation, casks are also 'fined'. This process involves the injection of a small volume of isinglass to the beer as each cask is filled. The purpose of this is to make the yeast flocculate and then settle to the bottom of the cask so that bright beer can be drawn off.
Conditioning
Beers for bottling, canning and kegging are 'Conditioned' in tank prior to packaging. These beers are chilled to near freezing point and stored at this temperature for some time, prior to filtering out the protein hazes which develop at this temperature. This process enhances the keepng qualities and prevents a 'chill haze' developing if the beer is chilled by the customer before serving.
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