consumer acceptability of spiced composite bread - The Federal ...

2.1.3 WHEAT MILLING
Present-day milling processes begin with the cleaning of kernels. Wheat arriving at a mill is
generally mixed with such matter as straw, chaff, pebbles, earth, and seeds of various kinds.
Coarse and fine material is removed by passing the wheat through sieves, but seeds and other
objects that approximate wheat grains in size must be extracted by special means. Cylinders
and disks that have perforations of various sizes not only separate remaining foreign particles
but also segregate wheat kernels by size. Next, the wheat is scoured by being passed through
an emery-lined cylinder. Tempering, a process by which the moisture content is adjusted for
easiest separation of kernel from husk, is the last step in preparing the grain for grinding.
Because of the development of wheat varieties that do not require the heavy friction provided
by millstones, most grinding is done in roller mills. Corrugated rollers gradually reduce
wheat kernels to powder, effecting separation of kernel and husk. Initial rolling takes place in
three to six stages, the last stage of which yields bran, middlings, and flour. Finished flour
consists almost entirely of endosperm, or nutritive tissue. Middlings are composed of
fragments of endosperm, fragments of husk, and husk fragments with adhering particles.
Bran, the broken husk of the grain, is used as feed for livestock and to provide roughage in
some types of breakfast cereals.
Between each of the stages of rolling, and following the final stage, the ground product is
sifted, a process referred to by millers as bolting. Three types of sifters are in common use:
the plansifter, composed of a series of sieves arranged one above another; the reel, covered
with silk bolting cloth or wire of a gauge that retains middling; and the centrifugal, an
adaptation of the reel equipped with beaters that hurl the product the length of the reel.
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