Grist or “ground grist” refers to malt and cereal that is ground (milled) in the brewhouse by a malt mill at the beginning of the brewing process. The mills can be of various designs and contain one, two, and often three pairs of rollers, or in the case of breweries which require a very fine grist, hammer mills. Malt has traditionally been milled in a dry state, but modern breweries often use “wet milling,” which can be more efficient.
Grist can be separated into six categories, the three main ones being husk, grits, or flour. The equipment the brewery uses to extract wort from the malt determines the specification of the grist, with British mash/lauter tuns requiring a coarse grind, European lauter tuns a medium grind, and mash filters a fine grind. Breweries monitor and control the milling process by measuring the different proportions of the grist. If a grist has too much flour (too finely ground) the wort separation (run off process) will be too slow. If a grist is too coarse (not finely ground enough) the wort separation will be fast, but the extract yield will be low and the brewing value lost. The term “grist” is also used to refer to the “grain bill” of a beer or the cereal part of the recipe. Therefore, a brewer may refer to a beer “brewed from a grist containing 90% pale malt and 10% crystal malt.”