- The best thing since sliced bread may be bread crust:
Researchers in Germany have discovered that the crust is a rich source
of antioxidants and may provide a much stronger health benefit than the
rest of the bread.
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- This is good news for those who like to complement their
holiday meals with bread stuffing, which is rich in crust, but bad news
for those who prefer to remove crusts from their bread, as they may be
sacrificing healthful antioxidants. The research findings are scheduled
to appear in the Nov. 6 print issue of the Journal of Agricultural and
Food Chemistry, a peer-reviewed publication of the American Chemical Society,
the world's largest scientific society.
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- Although previous studies have suggested that bread contains
compounds that have a cancer-fighting potential, much focus has been placed
on its abundance of dietary fiber, which is believed by some to help prevent
colon cancer. The current study is the first to identify a cancer-fighting
compound that is concentrated in the crust, says Thomas Hofmann, Ph.D.,
lead researcher for the study and formerly with the German Research Center
of Food Chemistry in Garching, Germany. He is currently a full professor
at the University of Munster, Germany.
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- Using a conventional sourdough mixture containing rye
and wheat flour, Hofmann and his associates analyzed bread crust, bread
crumbs (the pale softer part of the bread) and flour for antioxidant content
and activity. They found that the process of baking bread produced a novel
type of antioxidant, called pronyl-lysine, that was eight times more abundant
in the crust than in the crumb. The compound was not present in the original
flour.
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- Using human intestinal cells, Hofmann's collaborator
Veronika Faist, Ph.D., a researcher at the Institute of Human Nutrition
and Food Science in Kiel, Germany, showed that this crust-derived antioxidant
is the most effective component in bread for boosting the level of phase
II enzymes, which have been shown in previous studies to play a role in
cancer prevention.
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- The researchers are currently conducting animal tests
to determine whether bread crust and pure pronyl-lysine actually boost
antioxidant levels in plasma, but results have not yet been published.
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- Pronyl-lysine is formed by the reaction of the protein-bound
amino acid L-lysine and starch as well as reducing sugars in the presence
of heat. Chemists have long known that this same process, called a Maillard
reaction, is responsible for producing the brown color associated with
the surface of baked breads. The same reaction also produces flavor compounds
and other types of antioxidants.
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- Pronyl-lysine is formed during baking in both yeast-based
and yeast-free bread, also known as "tea bread." 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, the researcher says.
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- In general, 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, says Hofmann.
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- Funding for this study was provided by the German research
associations FEI and the AiF and Germany's Ministry of Economics and Technology.
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- Note: This story has been adapted from a news release
issued for journalists and other members of the public. If you wish to
quote any part of this story, please credit American Chemical Society as
the original source. You may also wish to include the following link in
any citation:
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- http://www.sciencedaily.com/releases/2002/11/021105080817.htm
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