Researchers elsewhere had already shown, in laboratory experiments,
that gallic acid had antimicrobial effects. But the investigations Molyneux
directed are likely the first to find that an agricultural cropsusceptible
to infection by an aflatoxin-producing Aspergillus speciescan
actually prevent the Aspergillus from making aflatoxin.
The work paves the way for moving Tulare's gallic-acid-producing prowess
into vulnerable walnut varieties. Conventional walnut breeding is one
way to accomplish this.
Discovering More About Gallic Acid
Molyneux and Mahoney pinpointed Tulare walnuts' pelliclethe nutmeat's
thin outer coatingas the only source of the gallic acid. Exactly
how gallic acid disrupts the fungus's ability to produce aflatoxin isn't
clear yet, says Bruce C. Campbell, who heads the Albany research unit.
Preliminary research by Campbell and molecular biologist Jong H. Kim
suggests that Aspergillus may make aflatoxin in response to environmental
stress, such as drought.
More details about the gallic acid research appeared in the Journal
of Food Science.
The aflatoxin investigations were funded in part by the California-based
Walnut Marketing Board. California produces nearly all of the nation's
walnut crop. The 2003 harvest of 326,000 tons of in-the-shell walnuts
was worth about $355 million to growers.
This research may be good news for growers, as it might lead to new,
environmentally friendly strategies to undermine aflatoxin production
not only in walnuts and other popular tree nuts but also in other crops.By
Marcia Wood,
Agricultural Research Service Information Staff.
This research is part of Food Safety, an ARS National Program (#108)
described on the World Wide Web at www.nps.ars.usda.gov.
Russell J. Molyneux, Noreen
E. Mahoney, Bruce C. Campbell,
and Jong H. Kim are in the USDA-ARS
Plant Mycotoxin Research Unit, Western
Regional Research Center, 800 Buchanan St., Albany, CA 94710; phone
(510) 559-5812 [Molyneux], (510) 559-5971 [Mahoney], (510) 559-5846
[Campbell], (510) 559-5841 [Kim], fax (510) 559-5777.
"Walnuts' Anti-Aflatoxin Ally: Gallic Acid" was published
in the March
2005 issue of Agricultural Research magazine.
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