EHEC "How to disinfect your salad"

[Juliane]

Susan Sumner vom Virginia Polytechnic Institute and State University in Blacksburg reinigt rohe Produkte wie Salat, Tomaten mit
3 %Wasserstoffperoxid und Essig .

Auch bei Oberflächen und schneidbrettern soll es wirken:


http://www.sciencenews.org/sn_arch/9_28_96/food.htm
"How to disinfect your salad

Between May and August, food containing the especially virulent E.
coli known as O157:H7 poisoned more than 8,500 individuals in Japan,
including 6,000 children. This is the same strain of bacteria that
tainted hamburger sold at western outlets of a U.S. fast food chain in
1993 -- causing 700 illnesses and four deaths. But those were the
prominent outbreaks. Since the microbe's discovery in 1982, it has
become increasingly common; in the United States alone, it now
accounts for some 20,000 cases of food poisoning and 250 deaths
annually.

Though usually spread via raw beef or feces, the recent Japanese
outbreak may not trace directly to either. Indeed, Japanese health
officials reported last month that white radish sprouts, popular in
the local diet, might be responsible. Perhaps those radishes had been
fertilized with contaminated manure.

It takes more than a tap water rinse to dislodge E. coli and many
other microbial squatters. Though high temperatures kill them, cooking
is hardly a viable answer for lettuce, sprouts, and tomatoes that go
into your fresh salad. For these and other foods that are be eaten
raw, consider another solution -- well, actually two solutions, to be
delivered in tandem as disinfecting sprays, suggests Susan Sumner, a
food scientist at Virginia Polytechnic Institute and State University,
in Blacksburg.

While at the University of Nebraska (which she departed last month),
Sumner worked out the recipe for just such a sanitizing combo.
Lettuce

Dianne Peters of the University of Nebraska-Lincoln applies the first
of two sanitizing sprays to lettuce. Credit: Univ. of Nebraska Inst.
of Agricultural and Natural Resources.

First, she squirts a vegetable with 3 percent hydrogen peroxide, the
same strength available at the drug store for gargling or disinfecting
wounds. She follows this up with a mist of mild acetic acid, also
known as vinegar. In truth, she says, which solution is sprayed first
doesn't matter. Nor were her sprayers very fancy; she used the kind
that dampen laundry before ironing.

The solutions represent an adaptation of a chlorinefree disinfection
scheme she had been working on for red meat, and which turned out to
be effective for decontaminating carcasses. In the course of her more
recent studies, Sumner found that vegetables not only tend to come
from the garden or farm bearing far more germs than red meat does, but
they also hold onto germs more tenaciously.

Overall, most germs that show up on produce come from the soil and are
benign. However, worrying that more toxic germs spread by feces could
show up in organic foods fertilized with manure, and realizing that
there have been reports of Shigella on cantaloupe and Salmonella on
raw vegetables, Sumner decided to develop a bactericidal treatment for
restaurants and other purveyors of salads.

In her tests, she deliberately contaminated clean fruits and
vegetables with Salmonella, Shigella, or E. coli O157:H7 -- all
capable of inducing gut-wrenching gastroenteritis. On its own, the
hydrogen peroxide was fairly effective against all three germs, she
found. But the best results came from pairing the two mists. For
instance, she told Science News Online, "If the acetic acid got rid of
100 organisms, the hydrogen peroxide would get rid of 10,000, and the
two together would get rid of 100,000."

"What I really liked about this treatment," she adds, "is that every
[microbe] that drips off is killed." So you're not just transferring
disease-causing contamination from your food to the sink, drain, or
cutting board. Speaking of which, she notes that the paired sprays
work well in sanitizing counters and other food preparation surfaces
-- including wood cutting boards.

As for taste, the peroxide didn't leave any lingering flavors and the
vinegar, when applied to the skins of tomatoes and peppers, proved
hard to detect. While the vinegar's trace could be picked up on
lettuce, even that isn't necessarily a major drawback, Sumner notes,
especially if it's destined for a salad to be dressed with a
vinaigrette.
Rule

References:

Nathan, R. 1996. Japan's E. coli outbreak elicits fear, anger. Nature
Medicine 2(September):956.

Peters, D., S.S. Sumner, et al. 1996. Control of pathogenic bacteria
on fresh produce, a paper (abstract #168) presented in Seattle on July
2 at the 83rd annual meeting of International Association of Milk,
Food and Environmental Sanitarians.

Richert, R., J. Albrecht, S.S. Sumner, et al. 1995. Survival and
growth of E. coli O157:H7 on produce. 1995. Journal of Food Protection
58(Supplement):19.

Further readings:

Armstrong, G.L., J. Hollingsworth, and J.G. Morris, Jr. 1996. Emerging
foodborne pathogens: Escherichia coli O157:H7 as a model of entry of a
new pathogen into the food supply of the developed world.
Epidemiologic Reviews 18:29.

Raloff, J. 1996. Sponges and sinks and rags, oh my! Science News
150(Sept. 14):172.

Sources:

International Association of Milk, Food and Environmental Sanitarians
6200 Aurora Avenue, Suite 200
Des Moines, IA 50333-2863
E-mail: iamfes@dwx.com

Susan Sumner
Department of Food Science and Technology
College of Agriculture and Life Sciences
Virginia Polytechnic Institute and State University
Blacksburg, VA 24061-0418
E-mail: sumners@vt.edu

This week's Food for Thought is prepared by Janet Raloff, senior
editor of Science News."

[Juliane]

Bundesinstitut für Risikobewertung

Verbrauchertipps:

Schutz vor Infektionen mit enterohämorrhagischen

E. coli (EHEC)


Wann können sich EHEC

vermehren?





EHEC können sich in einem Temperaturbereich von

7 °C bis 50 °C vermehren, sofern im Substrat genügend

Nährstoffe und Feuchtigkeit vorhanden sind und andere

Einflüsse, wie Säure- und Salzgehalt, dem Wachstum

nicht entgegen stehen.



http://www.bfr.bund.de/cm/238/verbrauchertipps_schutz_vor_infektionen_mit_enterohaemorrhagischen_e_coli_ehec.pdf