Baking & Snack - May 2004 - 115

FLOUR

WHEAT FLOUR FUNDAMENTALS (Continued)
lower limit. In practice, bulk ﬂour generally contains
13.0% to 13.5% moisture, although this may vary according to climatic conditions. Flour reversibly adsorbs
and desorbs humidity from the air. A baker in a hot, dry
location or a cool, humid region should be aware that
pneumatic transportation of ﬂour in the plant, where it
is carried with ambient air, may affect actual moisture
of the ﬂour when it reaches the weighing bin.
In packaged cake mixes, moisture from the ﬂour
may react with the chemical leavening, causing some
deterioration (loss of CO2) during storage. For this
application, cake ﬂour is often dried to a moisture
content of about 8%. The improved storage stability
of the mix justiﬁes the expense involved in drying.
Carbohydrates. Starch is the main carbohydrate
of wheat and ﬂour. Normal wheat starch is made
up of about 25% amylose (the smaller, linear starch
molecule) and 75% amylopectin (the much larger,
branched molecule). In the presence of excess water,
as in an Amylograph, wheat starch gelatinizes at
about 65°C (159°F). In limited water systems, including most baking formulations, the gelatinization
temperature is 5°C to 15°C (9°F to 27°F) higher. In
extreme water-limited situations, such as cookie
dough, most starch granules never gelatinize.
Flour contains 1.0% to 1.5% sugars and dextrins.
These include glucose, fructose, maltose, sucrose,
melibiose, rafﬁnose, gluco-difructose, oligofructans,
and oligoglucans. Yeast prefers glucose and fructose
for fermentation, but it will synthesize the enzyme
maltase to hydrolyze maltose to glucose.
In a lean dough, the natural sugars alone are
not sufﬁcient to support the amount of fermentation
normally desired. The action of a-amylase on damaged starch (releasing dextrins) and b-amylase on the
dextrins (forming maltose) provides the substrate for
continued yeast fermentation. The addition of barley
malt or fungal amylase to a dough provides the
needed a-amylase; ﬂour contains sufﬁcient b-amylase
to hydrolyze dextrins for fermentation. The
addition of sugar to the dough eliminates the need for
added a-amylase, although the enzyme may be added
for other purposes such as improving pan ﬂow or
extending shelf life.
Protein. The protein content of wheat ranges from
7% to 20%. The actual protein content is governed
by several factors - genetics, geography, climate
conditions and nitrogen fertilizer application, if any.
Soft wheat generally contains protein in the range
of 7% to 11%; hard wheat has 10% to 17% protein;
and durum wheat 14% to 20%. Different varieties
within a species, grown under identical conditions,
may well have different protein contents. The
observed range of protein content in any one cultivar
may be quite wide due to environmental factors.
Protein is higher in the bran and germ portions of
the kernel than the endosperm, which is the source of
ﬂour. Thus, wheat containing 12% protein will yield
straight-grade ﬂour containing about 11% protein.

Increments of 0.8% to 1% are fairly constant across
different types of wheat. Of this 11%, about 2% will
be non-gluten proteins (mostly enzymes of various
sorts), while the other 9% is gliadin and glutenin.
These two proteins are the important ones with
respect to dough mixing and baking properties.
Bread bakers consider protein quality to be very
important. Flour from two different cultivars, at the
same protein content, may give quite different results
as with loaf volume in the bakery. Genetics accounts
for some of the performance differences, and certain
genetically determined types of glutenin subunits
result in stronger glutens than other types. As part of
the screening program applied to new varieties, acceptable results from bake testing are required before
the cultivar is released to the farmer.

Lipids. The wheat kernel contains about 3.5%
to 4.0% total fat. Approximately half is in the
endosperm, about one-quarter in the bran layers
and one-quarter in the oil-rich germ. The lipids in
the endosperm, which carry through to ﬂour, are of
interest to bakers since they play a role in the development of gluten during dough mixing and inﬂuence
the gluten quality.
Flour contains about 1.0% nonpolar lipids, mainly
triglycerides, and 0.8% polar lipids, phospholipids
and glycolipids. The phospholipids are essentially the
same as those found in soy lecithin. A glycolipid is a
diglyceride with an attached sugar, either galactose
or digalactose. These polar lipids are emulsiﬁers and
act as such during dough mixing. During mixing, the
lipids interact strongly with the gluten.

COMPOSITION OF MILL FRACTIONS
Mill fraction
HRW Wheatb
Flourb
Bran, crudeb
Germ, crudeb
Red dogc
Shortsc

Moisture
13.1%
13.4%
9.9%
11.1%
14.0%
14.0%

Protein Carbohydratea Fat
12.6%
71.2%
1.5%
11.9%
72.5%
1.7%
15.6%
64.5%
4.3%
23.2%
51.8%
9.7%
15.3%
64.9%
3.5%
16.7%
60.3%
5.0%

Ash
1.6%
0.5%
5.8%
4.2%
2.3%
4.0%

Dietary
ﬁber
12.2%
2.4%
42.8%
13.2%
8.8%
25.6%

a. Carbohydrate
includes dietary
ﬁber.
b. From US Department of Agriculture
"Nutrient Database
for Standard Reference," Release 13,
1999.
c. Adapted from
Pomeranz, Y., Bakers
Digest, 54(1):20,
1980.

Ultratex Moulder Panner
Precise adjustments for greater
control. Versatile design for
single line, continuous dough
pieces. Features include infeed
conveyor with pre-sheeting
roller, high-speed coiling conveyor,
four-piece panner. And a number
of options.

Stickelber Moulder
This industry standard features double
sided timing belts, easy-to-clean surfaces,
sealed A/C duster motors and much more.

For detailed information,
we invite you to call us
or visit our website.
1.919.735.4570 * apvbaker.com
For more information, see Page 162

May 2004/ BAKERS PRODUCTION MANUAL / 115

http://www.apvbaker.com

Baking & Snack - May 2004

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