Out with the old and in with the new, as the saying goes. Now, scientists in the Food Quality and Safety Research Unit at the National Center for Agricultural Utilization Research in Peoria, Illinois, have found a way to significantly reduce the amounts of solvents used in the laboratory analysis of fat in foods such as hamburger.
Janet M. Snyder, an ARS chemist, says her procedure cuts solvent use by as much as 98 percent by combining supercritical fluid extraction (SFE) with an enzyme catalyst—lipase.
SFE uses carbon dioxide gas under high pressure, which causes the gas to act like a liquid. In an extraction chamber, the fluid flows through a sample and dissolves specific chemicals—or fats, in the case of food extractions. The gas is then decompressed and harmlessly vented into the atmosphere, leaving the extracted fats behind.
In traditional extractions, scientists must use several milliliters of solvent and two or more steps to complete an extraction. By combining SFE and the lipase, the extraction can be completed in one step and without chemical solvent. The result is a more accurate fat reading for specific samples and less waste solvents to dispose of.
Food researchers are delighted to be released from their solvent dependency. Like chemists in analytical laboratories, they routinely perform large numbers of extractions every day. “Up till now, we’ve needed as much as 50 milliliters of solvent—a quarter cup—to perform one conventional extraction,” says Jerry W. King, an ARS chemist and expert in SFE. — By Dawn Lyons-Johnson, ARS.
USDA-ARS Food Quality and Safety Research Unit, National Center for Agricultural Utilization Research, 1815 N. University St., Peoria, IL