A process to
produce high-quality, gluten-free bread has been developed by U.S. Department of Agriculture
scientists in Manhattan, Kansas. Millions of Americans affected by
celiac disease are unable to digest gluten, a protein in flour from grains such
as wheat, barley and rye.
Chemists Scott
Bean and Tilman Schober at the Agricultural Research Service (ARS) Grain Quality and Structure Research Unit found
that by removing a certain amount of fat from a corn protein called zein, they
were able to produce a dough more similar to wheat dough, and free-standing,
hearth-type rolls that resemble wheat rolls. ARS is the chief intramural
scientific research agency of USDA.
Bean and Schober
had some success developing gluten-free pan bread from other grains, but they
couldn’t make free-standing rolls because the rolls spread out too much.
According to Bean, the bread was considered lower in quality than comparable
wheat bread. Gluten-free grains include corn, sorghum, and rice.
In previous
studies, Bean and Schober found that zein – a readily available byproduct from
corn wet milling and fuel-ethanol production – could be used to make dough that
was more similar to wheat dough. The dough still didn’t meet their standards,
though, because it lacked strength, and the rolls produced from it were too
flat.
Bean and Schober
discovered that removing more of the fat from the zein protein’s surface
allowed the proteins to stick to each other much like wheat proteins do, giving
the zein-based dough the same elastic properties as wheat dough.
According to
Bean, while the experiment made more acceptable dough, sorghum may prove to be
a better grain to use since it is a gluten-free grain. Bean used corn as an intermediate
step toward achieving the ideal in gluten-free breads: a wheat-like dough using
non-wheat proteins, resulting in products with a fluffy, light texture.
This research
may prove useful for the 2 to 3 million Americans who have celiac disease, a condition
in which the human immune system erroneously attacks gluten proteins, causing
severe diarrhea and inability to absorb nutrients. Gluten-free palatable rolls
from corn, rice and sorghum would be a welcome addition to their diet.
The research
results were published in the Journal of Cereal Science and
in the November/December 2010 issue of Agricultural Research magazine.
Leavened bread
has been around a long while-since the days of ancient Egypt, Babylon
and Greece,
in fact. Then, as now, it was made from wheat, or from a mixture of wheat and
rye. The elastic gluten in wheat is essential for bread to rise.
But a lot has
changed – today’s bread is mass-produced. Brews of yeast, made in huge vats,
are mixed continuously with flour, water, and other ingredients at one end of a
machine. At the other end, dough is squished out of a tube, shaped, and cut
automatically into loaves. The loaves drop into pans, rise, and are baked at
the rate of thousands an hour.
Our bread also
contains more ingredients and additives, which causes special problems for the
baker, miller, and farmer. Even the same classes of wheat can vary
significantly in baking qualities. And when these differences are great enough,
they can cause a lot of trouble in a bread factory!
For 50 years,
ARS laboratories have worked with all segments of the industry to help provide
consumers with uniform, flavorful, nutritious bread and other wheat products.
They identified and isolated wheat proteins not previously known to exist. They
showed that these proteins-gliadin and glutenin-contain a specific chemical
structure that affects mixing properties of flours in forming doughs. They
discovered the role of fatlike constituents in flour in controlling volume of
bread and size of cookies. They found that certain water-soluble proteins
called albumins are as essential as gluten in producing a good loaf of bread.
And, over the
years, ARS technologists baked thousands of loaves of bread to test different
flours and to determine the effects of new additives.
Busy though
scientists have been, research is accelerating. Today, with a sample no larger
than half a kernel, a chemist can analyze a type of gluten protein and
determine its baking properties. This can help wheat breeders get an early
indication of the kind of flour their most promising plants will produce.
“It provides us with an incredible amount of information,” says one
researcher. “And it gives it to us in a day instead of in months or
years.”
Other scientists
work with glutenin, the other important protein in wheat gluten. Not all
glutenins, it turns out, are created equal. A team of chemists is exploring the
structure of glutenins of assorted molecular weights, shapes, and sizes. The
research could help in the genetic engineering of glutenins that can outperform
those of today.
