It is a simplified version of a commercial mill having 3 break and 3 reduction rolls. The grain passes initially through the break rolls where flour released is screened out by the sieves. Material too large to pass through the sieve is conveyed to the next break roll. Material passing over the top of the last break roll sieve is collected as the bran fraction. Following milling the flour and various mill fractions are weighed and the milling yield calculated on a percentage recovery basis.
Flour yield depends on variety, season, locality and grain plumpness.
The policy to exclude red grained wheats from Australian breeding programs has enabled us to market our wheat as one with excellent flour colour. Flour colour depends on the variety and flour extraction rate. The Kent-Jones Colour grader which is used to measure colour is a valuable measure of the freedom of the resulting flour from finely divided bran specks and the actual colour of the endosperm. There is no direct relationship of wheat protein to flour protein because of the different flour extractions. The physical properties of wheat-flour doughs such as their extensibility and resistance to extension influence their mixing behaviour very strongly.