Stage 1: Primary processing of wheat into flour

Flour is produced by milling grain. The main type of flour used in the UK for bread and baking is wheat flour, but other grains can be milled to make flour, egs. rye, barley, oats, rice.

Milling is the process of breaking open the grain and releasing the starchy centre.

The tougher outler layers may be removed and used for other purposes, egs. bran is used for breakfast cereals or animal feed.

A wheat grain contains:

  • endosperm - the starch centre containing vitamins, protein and starch
  • bran - the tough outer skin of the grain, containing vitamins, minerals, protein and fibre
  • germ - the seed of the grain containing vitamins, fat, iron and protein

 

Cleaning - the wheat is cleaned to remove stones, dust, grit, metal and any other impurities. This is done using: magnets to remove metal, aspirators (uses air to remove light dust) and scourers (equipment that rubs dust from the grain).
Conditioning - water is added to soften the wheat and make it easier to process.
Breaking - the wheat passes through rollers which break or crack open the grain.
Sieving - a series of sieves separate the grain into its three component parts - endosperm, bran and germ. The starchy endosperm passes through more sieves and rollers, getting finer as it goes.
Different types of flour
Different types of flour can be produced by milling to different extraction rates, as shown in the table below.


The extraction rate (in brackets) refers to the percentage of the whole grain that is used in producing the flour.

 
Type of flour


 How it is produced
White flour (75%) made by removing the germ and bran, leaving only the white endosperm
Brown flour (85%) some, but not all, of the germ and bran are removed
Wholewheat, wholegrain or wholemeal flour (100%) the whole of the grain is used, nothing taken out

 

To explore the whole process in more detail
go to the Wright's flow diagram.

 

 

 

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