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December 2001
Vol. 4, No. 12, pp 15.
news in brief
Forest of food defense
opening artAn extract from the larch tree, prevalent in the northwestern United States, has been shown to suppress the growth of Salmonella in chicken and E. coli in meat, and it may soon be marketed for such purposes. Discovered at the University of Montana in Missoula by carbohydrate chemist Geoffrey Richards, the wood extract has been patented by the University of Montana and licensed to Larex, Inc., in St. Paul, MN, for commercial development.

The extract, which has little color or flavor, contains the polysaccharide arabinogalactan as well as polyphenols. Arabinogalactan has been on the FDA’s Generally Regarded as Safe list since 1985 for use as an emulsifier and stabilizer, whereas polyphenols, such as flavonoids, occur naturally in many plant foods. Of the two major components, “polyphenols are the active bacterial suppressant,” says Richards.

“When you take chicken and rinse it with a 5% solution of this larch extract, then expose chicken meat to Salmonella, the subsequent growth of Salmonella is very much slowed,” says Richards. “The larch extract solution can protect chicken from contamination by dirty surfaces during processing.” In similar experiments with fresh beef, Richards also demonstrated that the extract suppresses the growth of E. coli. The larch extract blocks bacterial growth 30–70%, depending on the test conditions. The extract can be applied by dipping, rinsing, spraying, or brushing, and can be used to protect meat, poultry, eggs, vegetables, and fruit.

Founded in 1993, Larex manufactures various arabinogalactan-based products from larch trees, including a stabilizer for cosmetics, a dietary fiber supplement for humans, and a probiotic to prevent diarrhea in farm animals. The company isolates its extracts from the bottom 15 feet of the tree trunk, which is generally discarded by the lumber industry.

Researchers at Larex plan to develop a dipping solution for use in meat and poultry processing plants. A home-preparation product for cleaning sinks and countertops may be added later. Although the mechanism of action of the extract remains unknown, chemical toxicologist Sandy Bigelow, vice president of research and development at Larex, suggests that because arabinogalactan is a natural emulsifier and stabilizer, it likely makes the cell surface of food bacteria more sensitive to the antibacterial action of the polyphenols. “We need more testing”, says Bigelow, “to prove effectiveness and mechanism of action before marketing it to the poultry and meat processing industry.”

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