Agriculture Reference
In-Depth Information
ingredient of food products such as icing-sugar
mix, baking powder, frosting, chewing gum,
marshmallows, salad dressing, frozen desserts,
and coffee whitener, in addition to a large number
of nonfood uses (Lawton 2004). There is a further
range of uses for chemically and physically modi-
fi ed wheat starch (BeMiller 2004).
The production of biofuels represents an
increasing use of cereal grains, mainly via the fer-
mentation of starch into ethanol. Corn (maize) is
a primary raw material for this purpose, but wheat
use for ethanol production has long been linked
to the production of vital wheat gluten, with high-
grade starch being used for special purposes,
leaving poorer starch for fermentation (Maningat
and Bassi 2004).
ment (Posner and Hibbs 2005). The grain should
provide a high yield of white fl our. In addition,
for bread baking, the miller prefers grain that will
produce fl our with high water absorption to
increase economic returns. Hard-grained wheat
is thus used to produce fl our of moderate starch
damage, ensuring high water absorption and
adequate substrate to produce fermentable
sugars.
High protein content and good dough strength
are needed for long-fermentation baking proce-
dures to ensure that the bubble structure devel-
oped during mixing does not collapse during
fermentation. However, medium dough develop-
ment time may be preferred to minimize the
mixing energy required to develop the dough
fully. A dough with long stability to overmixing
offers fl exibility in manufacture. Bread is also
produced commercially by the rapid-dough and
sponge-and-dough processes, and optimum
ranges of protein content differ slightly from
that for the straight-dough—bulk-fermentation
process. Bright white fl our (high L*) with low
yellow color (low b*) is preferred, although lipox-
ygenases from added soy fl our may bleach non-
white color present in the original fl our.
PROCESSING SPECIFICATIONS FOR
WHEAT UTILIZATION
Wheat, once a commodity, is now traded to a
signifi cant extent with detailed specifi cations
defi ned by processor requirements (see Chapter
19 and Khan and Shewry 2009). In addition,
niche markets are arising for which even stricter
specifi cations must be met. Basic specifi cations
relate to soundness, lack of contaminants and
defects, bulk weight (indicating grain plump-
ness), grain color (red or white), grain hardness
(hard or soft), and protein content. Undesirable
defects for all products include the presence of
α-amylase activity, either from preharvest sprout-
ing or from a genetic defect termed late-maturity
α-amylase (LMA). For products with color spec-
ifi cations, low levels of polyphenol oxidase are
desirable.
The more detailed range of specifi cations for
individual products (listed in Table 21.1) pro-
vides a basis for breeders in targeting cultivars
tailored to specifi c grades, as well as forming
grade targets for postharvest segregation and
marketing. The level of dough strength varies
widely among these products, but good dough
extensibility is generally desirable.
Pan bread
As the products in Table 21.1 are made from
white fl our, milling quality is a primary require-
Flat bread
Flat bread, popular in Middle East and in the
Indian Subcontinent, varies considerably in
form and quality characteristics (Table 21.1). In
general, its production involves short high-tem-
perature baking. As various fl at breads have a high
ratio of surface area to volume, it is important that
moisture is retained in the dough for as much as
possible of the short baking time. The fl our (or
wheat meal) should thus have very high water
absorption.
For pocket bread, a dough of high extensibility
and medium dough strength is needed for the
production of circular dough pieces of appropri-
ate thickness. Poor dough strength results in an
elliptical shape. Excessive dough strength causes
the dough piece to shrink after sheeting, so that
the dough is too thick, leaving a “doughy” loaf
with blisters on the circumference.
