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Getting the Good Stuff With Supercritical Fluid Extraction
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Margarine-based products marketed
to lower cholesterol.
(K9553-8)
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The road to producing more nutritious
foods for health-conscious Americans may be paved by
ARS scientists using an environmentally
safe processing method known as supercritical fluid extraction (SFE).
After decades of using SFE, researchers at the National Center for Agricultural
Utilization Research (NCAUR), in Peoria, Illinois, have expanded its
application far beyond decaffeinating coffee and extracting hops for beer
flavoring. They have used SFE to extract and enrich nutritionally beneficial
compounds called nutraceuticals from rice bran, corn fiber or bran, and
soybeans. The goals are to provide alternative sources of nutraceuticals and to
find value-added uses for byproducts of the oilseed and milling industries.
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Extracts from oil fractionations
performed on rice bran. Each has
different properties and nutritive
values.
(K9550-3)
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Plant-derived oils contain
nutraceuticals that have recently been shown to enhance human health. For
example, rice bran, soybean, and corn fiber oils all contain significant levels
of compounds called phytosterols, according to ARS chemist Jerry W. King, who
is with NCAUR. Touted for their cholesterol-lowering properties, phytosterols
are found in commercially prepared margarines and spreads.
SFE is both an environmentally and consumer-safe way to extract such compounds
because it uses carbon dioxide that's been heated and compressed to a
semiliquid state. Previous articles described the use of SFE to replace organic
solvents in laboratory analyses or to remove fat from meats. (See
Agricultural Research, "Supercritical Fluid Fat Extraction,"
March 1995, p. 18, and "Cutting Use of Laboratory Solvents," March
1993, p. 12.) |
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To produce margarine that
is low in trans fatty
acids, chemist Gary List
uses high-pressure
hydrogenation in stirred
reactors.
(K9552-1)
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King and Scott L. Taylor, also at
NCAUR, have combined this benign method with solvents generally recognized as
safe, such as ethanol and water, to selectively extract and enrich target
nutraceuticals from vegetable oils. Using these natural and food-consumable
solvents, they have created an extract containing 14.5 percent
ferulate-phytosterol esters—compounds that other ARS researchers have
found will lower cholesterol in humans.
More recent SFE-related projects by Taylor have yielded phospholipids from
soybean oil. He combined two steps that occur during processing—extraction
and chromatography—which also use only carbon dioxide, ethanol, or water
as solvents. These are the only processing agents that are in contact with the
soybean oil and meal. The isolated phospholipid concentrates are purported to
provide such health benefits as improving cognitive function. |
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Chemist Jerry King removes
rice bran oil extract from
a high-pressure fractionating
column. The extract contains
an enriched level of phytosterols.
(K9549-1)
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Former research associate Nurhan T.
Dunford took supercritical fluid technology one step beyond the extraction
stage. With engineering technician Jeff Teel's assistance, she built a
fractionating column—similar to ones that produce distillates for the
petroleum industry—to obtain and enrich the desired nutraceutical
component without using chemical extraction solvents. This continuous system is
called supercritical fluid fractionation (SFF), which yields
phytosterol-enriched fractions from crude vegetable oils.
"SFF is feasible for industry to use, since they currently use a costly
and complicated process to extract nutraceuticals from oils and then add them
back into the product," says Dunford. She's now examining rice bran oil
for enriching oryzanol, a compound that is known to lower the cholesterol
levels in humans. |
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Supercritical fluid extraction
is an environmentally safe
method to extract nutraceuticals
from brans. Here, chemist
Scott Taylor examines corn
bran oil processed by SFE.
(K9551-1)
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Another NCAUR scientist,
Gary List, collaborating with King, has used a hydrogenation reaction
in the presence of carbon dioxide to produce a product with reduced trans
fatty acid content that could be used in margarine formulations.—By
Linda McGraw,
Agricultural Research Service Information Staff.
This research is part of Food Safety, an ARS National Program (#108)
described on the World Wide Web at http://www.nps.ars.usda.gov.
Jerry W. King and Scott
L. Taylor are in the USDA-ARS New
Crops and Processing Research Unit, National Center for Agricultural
Utilization Research, 1815 N. University St., Peoria, IL 61604; phone
(309) 681-6203 (King), (309) 681-6204 (Taylor), fax (309) 681-6686.
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"Getting the Good Stuff With Supercritical Fluid
Extraction" was published in the
August 2001
issue of Agricultural Research magazine.
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