Although Listeria is relatively rare, it is considered the most deadly
of the foodborne pathogens, with a 20 percent fatality rate. The Clinton
administration issued a "no tolerance" edict for Listeria
in processed and ready-to-eat foods, such as hot dogs, and in dairy
products. Under the policy, if one organism is found on a piece of food,
the whole batch must be discarded and/or recalled from stores, warehouses
and consumers' shelves.
In addition, the FDA requires that sanitizers be effective enough to
reduce organisms by at least 100,000-fold for Listeria, E. coli O157:H7,
and Salmonella. In this study, Linton and his team achieved this level
of Listeria elimination on the apple skin. Even on the stem cavity and
calyx, the gas reduced the pathogen to a far greater extent than currently
possible with other methods.
Another of the paper's authors, Purdue food science researcher Yingchan
Han, says Listeria was used for the study because it's hardy; it survives
refrigeration; and it is difficult to inactivate.
"Using the chlorine dioxide gas makes it possible to reduce the
bacteria before the apples are cut up or mashed, a significant breakthrough
for decontamination processes at small juice-producing companies,"
Han says. "They often don't have the pasteurization heating systems
necessary to meet USDA requirements for eliminating biological contaminants."
Linton and Han said they don't believe this process will work well
on already cut fruits and vegetables, and not at all for some varieties,
such as lettuce, because it would likely affect the color.
Contact Richard Linton at linton@purdue.edu
Page 1 | Page
2
