New Research on Gluten-Free Bread

USDA scientists, using a corn protein, are producing a gluten-free bread dough similar to wheat dough, although they say more research is needed.

Bread with a new protein to help those suffering from celiac disease.

Bread with a new protein to help those suffering from celiac disease.

courtesy Scott Bauer/ARS

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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.