A group of German scientists published these findings in the Nov. 6 issue of the Journal of Agricultural and Food Chemistry.
Previous studies have suggested that bread contains compounds that have cancer-fighting potential. However, most of the focus has been on dietary fiber, writes study researcher Thomas Hofmann, PhD, professor at the University of Munster in Germany.
This is the first study to identify a cancer-fighting compound concentrated in the crust, says Hofmann in a news release.
To test their theory, the researchers first baked a conventional sourdough bread containing rye and wheat flour. They then analyzed the bread crust, bread crumbs (the paler, softer part of the loaf), and the flour for antioxidant content and activity.
In the crust, they found eight times more of an antioxidant called pronyl-lysine than in the crumbs. The original flour contained none of the compound.
Pronyl-lysine is formed during baking in both yeast-based and yeast-free bread.
To see if pronyl-lysine is absorbed in the body, researchers tested it with human intestinal cells. They found that pronyl-lysine significantly boosted the level of certain enzymes that play a role in cancer prevention, studies show.
The next step: To determine whether bread crust and pronyl-lysine actually boost antioxidant levels in the blood. The German researchers are currently conducting those tests.
The antioxidant is likely to be more abundant when bread is broken down into smaller pieces and baked, as with stuffing, because the smaller pieces contain more surface area on which these reactions can occur in comparison to larger bread products, like loaves and buns, Hofmann says.
Dark-colored breads (such as pumpernickel and wheat) contain higher amounts of these antioxidants than light-colored breads (such as white bread). Strong over-browning of bread, however, reduces the level of these antioxidants, he adds. -->