Waxy Wheat Opens Doot to Fat Free Breads

WASHINGTON - Mar 5/02 - STAT -- USDA researchers have bred a new class of durum wheat, called "waxy wheat", which can replace shortening in bread without changing the baking characteristics of the loaf.

In commercial baking, vegetable oil or other types of fat often are added to dough to produce loaves of bread with improved crumb softness, volume and texture. Shortening also keeps the bread from becoming stale too quickly during storage. But vegetable shortening is high in trans fatty acids and can be a costly ingredient to add when millions of loaves are being produced, according to chemist Doug Doehlert at the ARS Red River Valley Agricultural Research Center in Fargo, N.D.

There, he and North Dakota State University (NDSU) associates show that flour from the new waxy durum wheat (WDW) can replace vegetable shortening without losing the desired properties the shortening confers to bread. A single bread loaf might have two tablespoons of shortening, so replacing that with WDW flour would save about 26 grams of fat, or 234 calories. Doehlert credits the flour's fat-replacing capacity to a unique type of starch that differs from that in most bread wheat cultivars.

Starch is a polymer, or chain, of glucose molecules containing both amylose and amylopectin. Amylose is the straight-chain form of this polymer, while amylopectin is the branched form. Most wheat cultivars have about 24 percent amylose and 76 percent amylopectin. But WDW starch is nearly 100 percent amylopectin.

WDW flour works best as a shortening substitute when it comprises 20 percent of a dough formulation, according to Doehlert, at the center's Cereal Crops Research Unit. In trials, quarter-pound loaves of the experimental bread had the same softness, texture and volume as those containing 100 percent bread wheat flour and 3.25 grams of shortening. And in tests for freshness, the WDW bread stayed much softer than the nonwaxy wheat bread after five days of storage.

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