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Milling
The mill at used at Broughton is a Porteous 4 roll mill consisting of a set of two top rolls and two bottom rolls with a set of beaters between them.
The diagram shows the internal lay out of the mill.
The milling of the malt is critical to the brewing process. The purpose of milling is to break open the malt corn and break up the malt starch it contains to allow the malt enzymes to penetrate the starch more efficiently during mashing. However it is not just a question of grinding the malt to a powder but breaking it in such a way that the husk is broken open but left more or less whole and the malt starch is broken into small granules with only a small amount of powder.
The importance of milling in this way is explained in the section on mashing.
The setting of the gaps between the two sets of rolls control the effectiveness of the milling process.
Pale ale malt and the various coloured malts are all passed through the mill and the resulting material is named “grist”, hence the old expression “it’s all grist to the mill” .
Other raw materials such as the pinhead oats used in the Oatmeal Stouts by-pass the mill and go directly to the grist case along with the grist.
