The Milling Process
The milling process has evolved from the days of grinding the wheat between two large stone wheels (although this process does still occur in a few mills), to the modern rollermill.
The modern rollermill consists of two cast steel rollers set slightly apart from each other. The top roller runs at a slightly faster rate to the lower roller; when wheat passes through it creates a shearing action, opening up the wheat grain.
The various fragments of wheat grain are separated by being passed through a complex arrangement of sieves. White endosperm particles known as semolina will be channelled into a series of smooth reduction rolls for final milling into white flour
In a typical mill, there may be up to 4 break rolls and 12 reduction rolls, which leads to the production of some 16 flour streams, a bran steam, a germ stream and a bran/flour/germ "wheat feed" stream.
The modern milling process allows the miller to remove the bran particles from the endosperm; grind the endosperm into flour; sift the ground stock and remove flour produced at each stage.
Millers may blend different wheats prior to milling in order to achieve a specific grist. However, they may also blend different flours in order to produce the product demanded by their customers. By blending together the many different flour streams produced by the mill, a miller can create further variations in features such as flour colour.
Very white flours would come from the early streams only, while brown flours involve using most streams. Wholemeal flour is produced when all the streams, bran, germ and flours are blended back together with nothing removed.
Examples of the types of flours produced in the UK are: white bread flours; brown bread flours; wholemeal flours; patent flours; cake flours; biscuit flours; pastry flours; household flours; brewery flours; and flours for starch/gluten separation.
Finally, the flour is sifted before delivery to the food manufacturer, bakery or retail outlet either in bulk or bags.