International Specialty Supply
Supplying Sprout Companies Throughout the World
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International Specialty Supply Supplying Sprout Companies Throughout the World
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Food
Irradiation and Chlorine Team Up to Kill E. coli O157:H7 and Salmonella By Doris Stanley Lowe Treating
alfalfa seeds and sprouts with a combination of irradiation and chlorine
effectively safeguards them against contamination by E. coli O157:H7 and Salmonella,
Agricultural Research Service scientists
report. ARS
scientists Donald W. Thayer, Kathleen T. Rajkowski and William F. Fett found
that a treatment of irradiation and chlorine solution not only killed both
organisms, but extended the shelf life of sprouts from about
five days to more than a week. They conducted the lab studies at the ARS Eastern
Regional Research Center’s Food Safety and Plant
Science and Technology Research Units in Wyndmoor, Pennsylvania. The
research is part of the effort by a task force of representatives from several
Federal Government agencies and industry to find ways to control microbial
contamination of sprouts . The
finding is good news for sprout growers. Since 1995, raw alfalfa sprouts have
been recognized as a source of foodborne illness in the United States, with
several outbreaks of both E. coli O157:H7 and Salmonella. FDA and
the Centers for Disease Control and Prevention
have advised those at high risk—including children, the elderly, and persons
with compromised immune systems—to avoid eating raw alfalfa sprouts. Since
sprouts can’t withstand abrasive physical washing because of their fragility,
cleaning the seed has become the primary focus. In the
tests, the scientists used the irradiation dose approved for irradiating meat.
The U.S. Food and Drug Administration (FDA) has
approved ionizing radiation as a safe and effective food preservation tool. Along
with irradiation, they subjected alfalfa seeds to 2-percent, 2.5-percent, and
3-percent weight-per-volume concentrations of calcium hypochlorite (a chlorine
source). A 3-percent concentration equals about 20,000 parts per million of
available chlorine. With a neutral pH of about 7, the 2.5 and 3-percent
concentrations reduced E. coli O157:H7 99.99 percent. The pH level is
important because at a higher pH level, such as 10, the chlorine would change to
a form that would not be as effective in killing bacteria. According
to the scientists, the best way to eliminate pathogens would be a combination of
irradiation and sanitation treatments. This is because sprouts can be
contaminated internally, which would prevent a surface disinfectant from working
effectively. ARS is
USDA’s chief scientific research agency. More information on this story
appears in the agency’s June Agricultural
Research magazine, available at: http://www.ars.usda.gov/is/AR/archive/jun99/food0699.htm
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