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Gene Found for Keeping Citrus Juice SweetBy
Kathryn Barry Stelljes
August 24, 1998
Fruit juice of the future could stay sweeter longer--and might be even more
nutritious. That's because scientists now have isolated the gene for a key
citrus enzyme. Shin Hasegawa, a biochemist with USDA's
Agricultural Research Service in Albany,
Calif., presented the findings yesterday at the American
Chemical Society's 216th Annual Meeting in Boston.
Sweet, fresh-squeezed citrus juice can turn bitter after only a few hours.
But a decade ago, Hasegawa discovered that oranges, grapefruits and other citrus
contain an enzyme called limonin glucosyltranferase (LGT). LGT converts the
bittering agents into tasteless compounds called limonoid glucosides.
Now researchers at the Japanese
National Institute of
Fruit Tree Science, who are collaborating with ARS, have determined the
genetic sequence of the enzyme. The team hopes to use the genetic information
to produce orange trees that bear fruit with more limonoid glucosides. That
would mean citrus juice that wouldn't turn bitter.
Another potential benefit of limonoid glucosides: university studies
suggest they may help prevent tumor formation. At
Baylor University College of Dentistry in
Dallas, limonoids inhibited experimentally induced oral cancer tumors in
hamsters. In a study at the University of Western
Ontario, Canada, the compounds inhibited proliferation of human breast
cancer cells in mice and cell culture. ARS provided the purified limonoid
glucosides for these experiments.
ARS and the Japanese researchers are applying for patent protection of the
gene. Earlier this year, ARS and a private Japanese company were awarded a
patent on a commercial process for extracting the limonoid glucosides from
Scientific contact: Shin Hasegawa, ARS
and Engineering Research Unit, Western Regional Research Center, Albany, CA
94710, phone (510) 559-5819, fax (510) 559-5963,
firstname.lastname@example.org. From August 22-26,
Dr. Hasegawa can be reached at Copley Square Hotel, phone (617) 536-9000, fax
(617) 236-0351 or through the ACS Press Room, phone 617-954-3476.