Putting the squeeze on produce to kill germs
Source of Article: http://ap.google.com/article/ALeqM5jxbyOeE1GGcs6O7cNNPk8eTgKM5QD92702SG0
WASHINGTON (AP) — Could food producers literally
squeeze the salmonella out of a jalapeno? Or zap the E. coli from lettuce
without it going limp?
Headline-grabbing food poisonings from raw foods are prompting new interest
in technology — from super-high pressure to irradiation — to get rid of some of
the bugs. It won't be a panacea: Far better to prevent contamination on the
farm than to try to get rid of it later.
"This is never an excuse for a dirty product," warns
But it's impossible to prevent all contamination in open fields. And
increasingly popular ready-to-eat foods — salads already washed and bagged,
fruit peeled and sliced — allow another processing step where a single slip-up
can introduce pathogens.
Washing, even with chlorine or other chemicals, only gets rid of surface
contaminants, not germs that sneak inside the fruit or vegetable. Enter high-tech
options.
At a Virginia Tech laboratory this summer, food scientists subjected small
grape tomatoes to what's called "high pressure processing" to see if
they could squeeze salmonella to death.
It's been known for decades that massive pressure — the equivalent of two
African elephants standing on a dime is how Tech microbiologist Robert Williams
puts it — can destroy certain pathogens. The question is how to kill the bugs
without smushing the food they're in.
Key is to choose a water-packed food with few air pockets. Put it in a
container of water and apply pressure evenly to all sides. Air pockets will
collapse but waterlogged tissue is more resistant.
Grape tomatoes emerged fine, says Tech food scientist George Flick.
But bigger beefsteak-style tomatoes cracked under the pressure. There's more
air inside the regular tomatoes than their tiny cousins.
Foods treated by high-pressure processing, or HPP, already are on the market
— particularly raw oysters treated to kill the vibrio
germs that proliferate in warmer waters, and processed meats treated to kill
dangerous listeria.
For more delicate raw produce, sliced fruits and vegetables seem to be HPP's main niche, says Errol Raghubeer
of Avure Technologies, the Kent, Wash.-based company
that makes high-pressure food processing equipment sold under the trade name
"Fresher Under Pressure."
First on the market: Sliced avocadoes and guacamole, when companies realized
that HPP treatment killed spoilage germs that rapidly turned cut avocadoes
brown, thus extending the products' shelf life.
Whole large tomatoes don't fare well but diced ones can if they're processed
in certain ways, Raghubeer says — and a number of
HPP-treated salsas are hitting the market.
Also arriving are ready-to-assemble fajita meal kits with little bags of
HPP-treated fresh, sliced jalapenos. Raw jalapenos have become the prime
suspect in the nationwide salmonella outbreak that sickened more than 1,200
people this summer.
A whole jalapeno goes limp when HPP treated because of its hollow center, but
diced jalapenos emerge just as crisp, says Raghubeer.
Simple physics is behind high-pressure processing. A different approach
under consideration by the Food and Drug Administration is irradiation, zapping
fruits and vegetables with enough electron beams or other radiation to kill
germs.
Irradiated meat has been around for years; it's considered particularly
useful in the ground beef that is a favorite hiding spot for E. coli. And while
irradiated foods initially caused some consumer concern, government scientists
make clear that the food itself harbors no radiation.
But early on, irradiation left lettuce and spinach limp and made tomatoes
mushy. That's changed, says
In studies of bagged salads, tailored irradiation doses
killed E. coli on nine different types of lettuces without harming the texture,
or affecting the taste of accompanying ingredients like tomatoes and cucumbers,
says Jeffrey Barach, director of the Grocery
Manufacturers Association's food laboratory. Killing salmonella takes a little
more energy, so producers would customize the beam to the need.
Barach's trade association has petitioned the FDA
to allow the irradiation levels, somewhat lower than meat requires, for produce
pathogen and other ready-to-eat foods, and hopes for approval by year's end.
Both high-tech options add to foods' cost, meaning they'd always be
something of a niche product. But parts of the population are particularly
vulnerable to food poisoning because of age or health conditions, a natural
market.
EDITOR's NOTE _ Lauran Neergaard covers health and medical issues for The
Associated Press in
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