World Grain - April 2019 - 57

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wheat varieties have been selected for high water absorption
and, hence, for thicker endosperm cell walls.
"Surprisingly, when bread wheat first formed 10,000 years
ago, it was soft," said Craig F. Morris, director, USDA Western Wheat Quality Lab.
All hard kernel wheats have since arisen via mutations in the
Puroindoline genes. Globally, soft wheats have largely taken
a back seat to hard wheats due, in part, to directed breeding
efforts, combining hard kernel and strong gluten. Hard wheats
do have an advantage in producing flours with higher starch
damage, which is good for dough fermentation and water absorption.
"However, for many low moisture products such as cookies
(biscuits) and crackers, starch damage and high-water absorption are undesirable," Morris said. "Soft wheats too can have
strong gluten. The glutenin and gliadin genes are independent
from the Puroindolines. Probably the biggest technical challenge related to soft wheat milling is that their flours, comprised of smaller mean particle size, do not flow well and require greater sifting/bolting surface."
SOFT WHEAT MILLING
Soft wheat breaks down more quickly than hard common
wheat. More flour is produced on the break system for soft
wheat than for hard wheat, requiring greater sifting capacity
for the former. Endosperm of soft wheat adheres more strongly to bran, reducing flour extraction rate expectations by up
to 2% unless sifting capacity is increased. Yield of semolina
and middlings is lower, so purifiers are of less importance and
often are absent. Stock is stickier and fluffier, which makes it
more difficult to sift than hard wheat stock. Soft wheat is fed
more slowly to the mill to facilitate sifting and to ensure that
stock flows freely through the mill. Generally, this results in
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Book 1.indb 57

lowering of production by about 25% to 30% when milling
soft wheat in a hard wheat mill.
"Soft wheat requires less tempering moisture (13% to
14.5%) and less time (4 to 8 hours) to rest in the tempering
process when compared to hard wheat," said Jeff Gwirtz, a
milling industry consultant and president of JAG Services Inc.
"Excessive temper moisture in soft wheat reduces the miller's
ability to sift efficiently and remove endosperm from the bran
as well as negatively impacting flow properties and mill balance. Soft wheat more easily releases its endosperm as flour
rather than granular endosperm particles requiring purification to classify compound particles. The flour generated from
soft wheat has a very fine particle size (D50=30 ± μm) when
compared to hard wheat flour (D50=62 ± μm). This contributes
to increased sifting and separation challenges in the mill often
requiring more sifter and roll surface and changes in allocation due to loading (see Figure 1, page 58).
"In the production of straight grade flour, the ash content
and yield differences between soft and hard wheat flour are
minimal. Generally, soft wheat will produce a slightly lower
flour yield with a somewhat lower ash content. Soft wheat
does produce significant quantities of low ash bright white
flour suitable to a variety of specialized products, including
cakes, cookies, pastries, pretzels and crackers. Soft wheat
millers must balance the technical requirements as well as
manufacturing economics to maximize resource utilization
while maintaining profitability."
POPULAR SOFT WHEAT PRODUCTS
Cake can be defined as a sweet, usually finely texturized
food product, baked in various forms that differ in size and
configuration. İt generally contains such ingredients as soft
wheat flour, milk or other liquids, sugar, eggs, chemical
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World Grain - April 2019

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