TRADE & MARKETS
Durum revisited
Bread & butter or pasta & sauce?
December 2012
By Scott A. Yates
When it comes to wheat, the words “hard” and
“soft” refer to the kernel’s milling characteristics.
Soft white wheat, as its name would suggest, has
a soft kernel trait making it among the easiest of
all classes to mill. On a scale of kernel hardness, it
comes in at between a 25 and 35. Hard red wheat,
meanwhile, comes in at 60 to 75 on the same index.
Durum wheat, however, is in a class of its
own. The hardest of all wheat classes, it ranks at
nearly 80 to 100 on the hardness index. As a result,
specialty mills specifically set up to grind durum
generally don’t bother making flour because of the
additional energy output, producing instead what
is called semolina, a gritty product resembling
coarse sand in texture that is used to make pasta,
couscous and other foods.
There is no reason for the durum kernel to
be so hard, said Craig Morris, director of the
Agricultural Research Service’s Western Wheat
Quality Lab in Pullman. It’s simply an evolutionary
happenstance. So, is it possible to convert durum
from an extremely hard kernel to something
as soft as soft white? And why would you? The
answer to the first question is yes. The answer to
the second is more complicated.
“The smart-aleck answer is that I like to make
up wheats that never existed before,” said Morris,
who has developed both a waxy wheat and a super
soft wheat. “The real answer is that I’ve spent a fair
amount of my career working with the underlying
genes related to kernel texture. By manipulating
those genes, I can develop new or innovative
classes of wheat with novel flour characteristics
that can be used to make things we haven’t been
able to make before.”
As Morris explains it, the fact durum isn’t
ground into flour limits its culinary uses. “World
durum production is not constrained by the plant,
it is constrained by what we can do with the grain.
But a soft durum can be used in many of the foods
currently made using conventional flour,” he said.
Although soft durum has a softer kernel, everything
else about the durum is the same. It looks the
Bread and butter? Or pasta and sauce?
same, it grows the same, it has the same disease resistance and
susceptibility. It is only when you bite down on a kernel, that
you realize something is different, Morris said.
“Everyone who has eaten products made from soft durum
remarks on the flavor, using adjectives like nutty. It kills as a
pizza crust,” he said, noting that its yellowish color in end-use
products is another attraction.
Although durum is included as one of the six classes of
wheat grown in the U.S., it’s actually a different species. Hard
red winter, hard red spring, soft white, soft red and hard white
are all what are called hexaploid. They have 42 chromosomes
located on AA BB and DD genomes of the plant. Durum, a
tetraploid, is a more primitive relative having 28 chromosomes
located on the AA BB genomes. It lacks the DD genome,
something hexaploid wheat borrowed in a cross with jointed
goatgrass.
Morris compares durum and the traditional wheat
classes to the difference between a chimpanzee and a
gorilla or a horse and zebra. They’re highly related, but
as different species, they can’t interbreed. That has made
durum’s conversion from a very hard kernel to a very
soft one a 15-year process essentially aimed at fooling
Mother Nature.
Leonard Joppa, an ARS scientist who worked at the
Northern Crop Sciences Laboratory in Fargo, N.D., before
he retired, began the initial research. Morris has been
working the last 10 years to breed two associated genes
that confer softness into durum, a process made more
difficult because these genes exists on the DD genome
that durum lacks.
Morris’ explanation of how the transfer of soft kernel
texture was accomplished is a complicated collection
of technical words. It would be helpful to have a cereal
science degree to fully understand them. In simpler
language, he was able to facilitate a romance between the
DD genome of a soft wheat and the AA or BB genome
of durum. Backcrossing multiple times restored order
and regulation to the plant. Once the trait was stable, he
crossed it into Svevo, a durum variety that is currently in
production in the desert Southwest and Italy.
“It is ready for prime time right now, and there are
several companies begging for a commercial license
to grow soft durum, but until a patent is secured, ARS
doesn’t enter into any licensing agreements,” Morris said,
adding that the patent application has, for the time being,
been languishing in the Patent and Trademark Office. He
hopes for a response within the next year.
Although Morris has, in essence, created a better
mousetrap, it is unlikely the world of semolina producers
will be knocking down his door. In fact, they may not be
particularly happy. Millions of dollars of infrastructure
needed to mill durum is already in place, and despite the
advantages in both lower energy consumption and more
culinary choices, “you don’t just chuck all that equipment
in the landfill without thoughtful consideration.”
Dan McKay, owner of McKay Seed, a company which
contracts for small amounts of conventional durum
wheat in Washington, said soft durum would require a
market development push akin to the efforts that have
gone into bringing the hard white wheat class to market—
with varying degrees of success. On the other hand,
he said there are clear advantages to having a soft durum
available, not the least of which is it could be milled in
existing soft white mills in the region.
Morris said soft durum could complement the classes
of wheat already being grown in Eastern Washington.
And in certain situations, it may do better than existing
alternatives.
“As a crop with a much longer evolutionary history,
durum is actually richer in terms of disease resistance.
And it has greater resistance to drought and heat, outyielding
hexaploids in those circumstances by 10 to 15
percent,” he said.
As for overseas markets, which are the bread and
butter of Northwest wheat producers, Morris said a soft
durum could provide customers an expanded product
portfolio without the need to build durum-specific semolina
mills. Having many of the same properties as soft
wheat flour, Morris said soft durum would significantly
expand the range of possible consumer foods.