USDA-ARS, NDSU Researchers Develop New Waxy Durum

Replacing Vegetable Shortening, the Wheat Flour Can Help Cut Fat, Keep Bread Fresh

Scientists at NDSU and the USDA-ARS Red River Valley Agricultural Research Center in Fargo have bred a new kind of durum wheat, called “waxy wheat,” whose flour may give rise to reduced-fat bread.

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 USDA-ARS chemist Doug Doehlert at the Fargo lab.

There, he and NDSU researchers have demonstrated 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% amylose and 76 percent amylopectin. But WDW starch is nearly 100% amylopectin.

WDW flour works best as a shortening substitute when it comprises 20% 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% 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.

Doehlert, along with ARS chemist Linda Grant and NDSU associates Monisha Bhattacharya, Sofia Erazo-Castrejon and Michael McMullen, have been developing, evaluating and testing applications for the new WDW flour for about five years.  After several years of field testing and seed increase, the new waxy durum will be released by NDSU as a cultivar, and it will be a prime candidate to be grown as an identity-preserved crop, according to Doehlert.

USDA-ARS chemist Doug Doehlert and NDSU cereal scientist Monisha Bhattacharya, have been involved in developing waxy durum, which holds promise as a replacement to vegetable shortening in making bread, without losing the desired properties the shortening confers to bread. Bhattacharya says partial waxy wheat may have beneficial applications in other wheat foods as well, including Asian noodles and frozen bread dough.
(Photo: Tracy Sayler)