
Cedarwood Oil: Making It More Aromatic, More
AvailableBy Linda McGraw June 17, 1999PEORIA, Ill., June 17--When you
can't see the forest for the trees, focus on the tree's valuable products. That's the approach that scientists Fred Eller and Jerry King at the
Agricultural Research Service have taken
in developing an environmentally safe method to extract more and better quality
cedarwood oil from juniper trees. The extraction method, known as supercritical fluid extraction (SFE),
already benefits consumers who drink decaffeinated coffee. Cedarwood oil--used in cosmetics, perfumes, home odorants, and as an insect
control agent--is usually extracted from sawdust and wood chips by steam
distillation. But this extraction method produces low oil yields and often
decomposes the oil, causing it to have an off-odor. In lab tests, Eller obtained 30 percent more oil than the yield from
conventional steam distillation without destroying the oil's aromatic
components. "Steam distillation doesn't penetrate deeply into chips, so it averages
only a 50 percent yield of the oil from the wood," said Eller, a chemist
at ARS' National Center for Agricultural
Utilization Research in Peoria, Ill. The presence of oxygen and high
temperatures in steam distillation also erodes oil quality. But SFE, which uses carbon dioxide (CO2), works better "because it
diffuses in and out of the wood more easily than steam, carrying the cedarwood
oil with it. The CO2 is then easily removed from the extract when the mixture
is depressurized. This leaves a more pure oil that's uncontaminated by solvent
residue," Eller said. Because SFE operates in an oxygen-free atmosphere, the oil's components
aren't degraded, making the cedar aroma more similar to the original wood chips
than the oil extracted by steam distillation. That's based on an odor analysis
by Peoria researchers. On Western rangelands, where cattle and wildlife subsist on forage grass,
juniper trees and shrubs are unwelcome inhabitants. The reason: The trees crowd
out forage grasses and deplete the soil of water and nutrients needed for other
plants. In the Midwest and Southwest, farmers and cattle ranchers routinely
remove junipers from fields and ranges at significant expense. Eller and King envision someday being able to develop a mobile SFE unit that
farmers could use to produce a value-added product. This could be an economic
boost especially for Midwestern farmers, where more land is being invaded by
junipers. Cedarwood oil is currently valued between $4.00 a pound (for Texas
oil) and $7.00 (for Virginia oil). Scientific contact: Fred J. Eller,
Food Quality and
Safety Research Unit, ARS National Center for Agricultural Utilization
Research, Peoria, Ill., phone (309) 681-6232, fax (309) 681-6340,
[email protected].
Story contacts Fred J Eller U.S. Department of Agriculture | |