Wheat Flour

Flour is the milled endosperm of the wheat kernel. The endosperm is the kernel’s starch and protein reserve; the bran is its protective outer layers and the germ is the embryo. Roller milling exists to separate these fractions cleanly, because they behave very differently in food use — bran and germ carry oil, fibre, and colour that change how a flour performs and how long it keeps.

Extraction rate

The proportion of the grain recovered as flour. Lower-extraction flours are whiter and contain less bran; higher-extraction flours retain more of the kernel.

Ash content

A mineral measure used as an indirect indicator of how much bran is present in a flour.

Wholemeal flour

Flour containing all of the kernel fractions in their original proportions.

Protein content and quality largely determine baking behaviour: higher-protein flours from hard wheats form stronger gluten networks suited to bread, while lower-protein flours from soft wheats suit biscuits and cakes. Particle size, damaged starch, and enzyme activity also matter, which is why flours are specified for a use rather than treated as a single commodity.

Flour is stored and shipped in bulk and in bags. It takes up moisture from the air, can support storage insects, and — because milling redistributes the kernel’s oil-bearing fractions — flours retaining germ have a shorter keeping quality than white flours. Storage conditions and stock rotation therefore matter to flour as much as to the grain it came from.