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Whole wheat flours
Whole wheat flours use every part of the
kernel: the fiber-rich bran with its B vitamins, the starch- and
protein-rich endosperm with its iron and B vitamins, and the oily germ
with its vitamin E.* Because they contain bran, whole-grain flours have
much more fiber than refined white flours. However, some studies suggest
that the size of the fiber particles may have some bearing on their
ability to absorb moisture and "bulk up" stool and that the fiber
particles found in fine-ground whole wheat flours may be too small to have
a bulking effect.
Finely ground whole wheat flour is called whole wheat cake flour; coarsely
ground whole wheat flour is called graham flour. Cracked wheat is a whole
wheat flour that has been cut rather than ground; it has all the nutrients
of whole wheat flour, but its processing makes it less likely to yield its
starch in cooking. When dried and parboiled, cracked wheat is known as
bulgur, a grain used primarily as a cereal, although it can be mixed with
other flours and baked. Gluten flour is a low-starch, high-protein product
made by drying and grinding hard-wheat flour from which the starch has
been removed.
Refined ("white") flours.
Refined flours are paler than whole wheat
flours because they do not contain the brown bran and germ. They have less
fiber and fat and smaller amounts of vitamins and minerals than whole
wheat flours, but enriched refined flours are fortified with B vitamins
and iron. Refined flour has no phytic acid.
Some refined flours are bleached with chlorine dioxide to destroy the
xanthophylls (carotenoid pigments) that give white flours a natural cream
color. Unlike carotene, the carotenoid pigment that is converted to
vitamin A in the body, xanthophylls have no vitamin A activity; bleaching
does not lower the vitamin A levels in the flour, but it does destroy
vitamin E.
There are several kinds of white flours. All-purpose white flour is a
mixture of hard and soft wheat, high in protein and rich in gluten.***
Cake flour is a finely milled soft-wheat flour; it has less protein than
all-purpose flour. Self-rising flour is flour to which baking powder has
been added and is very high in sodium. Instant flour is all-purpose flour
that has been ground extra-fine so that it will combine quickly with
water. Semolina is a pale high-protein, low-gluten flour made from durum
wheat and used to make pasta.
Rye flours.
Rye flour has less gluten than wheat flour
and is less elastic, which is why it makes a denser bread.**
Like whole wheat flour, dark rye flour (the
flour used for pumpernickel bread) contains the bran and the germ of the
rye grain; light rye flour (the flour used for ordinary rye bread) does
not. Triticale flour is milled from triticale grain, a rye/wheat hybrid.
It has more protein and less gluten than all-purpose wheat flour.
*The bran is the kernel's hard, brown outer cover, an extraordinarily rich
source of cellulose and lignin. The endosperm is the kernel's pale
interior, where the vitamins abound. The germ, a small particle in the
interior, is the part of the kernel that sprouts.
**Gluten is the sticky substance formed when kneading the dough relaxes
the long-chain molecules in the proteins gliadin and glutenin so that some
of their intermolecular bonds (bonds between atoms in the same molecule)
break and new intramolecular bonds (bonds between atoms on different
molecules) are formed.
*** Hard wheat has less starch and more
protein than soft wheat. It makes a heavier, denser dough.
Related Links
Flour and
Nutrient
Buying
and Cooking with Flour
Medical
Uses and Benefits of Flour
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