Supercritical Fluid Fat Extraction
It can put low-fat burgers on your menu.
Chemist Jerry King inserts ground beef patties into a
high-pressure extraction vessel where carbon dioxide will be used to reduce the
meat's fat and cholesterol content.
Meats like hamburger don't have to contain high fat and cholesterol, thanks
to fat-extraction technology developed by ARS chemist Jerry W. King.
"With supercritical fluid extraction, we compress and heat a
gasusually carbon dioxideso it becomes more dense and
liquidlike," King explains. "This liquid CO2 can then pass
through the meat and dissolve and pick up the meat's fat.
In experiments. King was able to extract an average of 4 grams of fat and 50
percent of available cholesterol from freeze-dried hamburger patties using the
supercritical fluid extraction (SFE) process.
"As we take the CO2 back out," King says, "the
dissolved fat comes with it. When the CO2 cools and decompresses, it
turns back into a gas and the fat particles fall out of it. The same thing
happens with the cholesterol in the meat."
SFE is already used by the food industry to remove caffeine from coffee and
extract beer hops. King has specifically designed and developed SFE methods for
food processing and chemical analyses. His research at the National Center for
Agricultural Utilization Research at Peoria, Illinois, has made the United
States a leader in the application of SFE for processing fat- and
oil-containing agricultural products.
Although King's experiments involved preformed freeze-dried patties, SFE can
also extract fat and cholesterol from fresh ground meat.
"But it might be less effective because of the fresh meat's water
content," notes King. "The water in the meat acts as a buffer around
the fat particles and can prevent the CO2 from getting to the
King had done earlier work on using SFE to remove pesticides from food for
analysis. After an article on that work appeared in Agricultural
Research magazine [March 1993, pp. 12-13], several companies called King to
inquire about the potential of SFE for removing fat and cholesterol from meat.
"Researchers have used this process to remove fat and cholesterol from
other food products, such as milk, eggs, and some meat products," King
"One advantage of using SFE to remove fat is that carbon dioxide is
almost always used in the process, and CO2 poses no threat to the
environment or human health," he says. "Since the fat that's removed
in this way hasn't been touched by a chemical solvent, it can be put to some
other useeven human consumption."
Meat processors may be inhibited by the high initial cost of SFE equipment,
says King. But he believes SFE can fill a niche market for low-cholesterol,
low-fat, freeze-dried meats.
King worked on the project in collaboration with Floyd K. McKeith, a meat
scientist in the Department of Meat Science at the University of Illinois at
Urbana. By Linda Cooke, ARS.
Jerry W. King is at the USDA-ARS
Center for Agricultural Utilization Research, 1815 N. University St.,
Peoria IL 61604; phone (309) 681-6541, fax (309) 681-6686.
"Supercritical Fluid Fat Extraction" was
published in the March
1995 issue of Agricultural Research magazine.