University of Georgia researchers have found that consumers
can reduce their risk of food-borne illness by washing lettuce
before preparing homemade fresh salads.
Fresh salads, particularly those made with lettuce, have been
linked to five outbreaks of E. coli over the past four years,
according to the Centers for Disease Control and Prevention in
Atlanta, Ga.
A Second Washing is a Good
Habit
“Lettuce is washed before it’s sold, but our research
has shown the risks of food-borne illness can be greatly reduced
by washing it again at home,” said Joe Frank, a food
microbiologist
with the UGA Center for Food Safety and Quality Enhancement in
Griffin, Ga.
Frank said lettuce is most likely contaminated in the field
by polluted irrigation water, animal manures or improper handling
by field workers.
To address the lettuce and E.coli problem, Frank studied how
and where E. coli cells survive on lettuce leaves.
“Lettuce breathes through stomata or holes on the
leaves,”
he said. “The E. coli cells attach to the surface around
and inside these holes.”
E. coli Likes Cut Edges and
Bruises
He also found E. coli cells favor
the cut edges of lettuce. “The edges of cut lettuce pieces
had tremendous numbers of attached E. coli cells,” he said.
“The bruised areas did, too.”
In the lab, washing the lettuce with a bleach solution was
found effective for removing the E. coli cells on the lettuce
surface.
“The solution removes or kills the cells on the surface
of the lettuce, but those inside the holes still survive,”
Frank said.
UGA food scientists are working with the food industry to
apply
this chlorine method. But Frank warns consumers not to try it
at home.
“Chlorine bleach is much too strong to be used at home
for rinsing vegetables,” he said. “Consumers shouldn’t
use chlorine to rinse vegetables at home.”
Wash Well and Keep it Cold
For your home, the main recommendations are to wash lettuce
and keep it cold.
“There is no way to totally eliminate your risk of
food-borne
illness,” Frank said. “But taking these precautions
can greatly reduce your risk.”
(Lettuce image courtesy Scott Bauer, USDA. E. coli image
courtesy UGA Center for Food Safety and Quality
Enhancement.)
