Posted on 04/14/2008 5:20:18 PM PDT by blam
Dr. Mom Was Right -- And Wrong -- About Washing Fruits And Vegetables
A new study shows that irradiation could be key to removing hard-to-reach pathogens inside fruits and vegetables. (Credit: Courtesy of USDA-Agricultural Research Service, photo by Stephen Ausmus)
ScienceDaily (Apr. 13, 2008) — Washing fresh fruits and vegetables before eating may reduce the risk of food poisoning and those awful episodes of vomiting and diarrhea. But according to new research, described recently at the 235th national meeting of the American Chemical Society, washing alone -- even with chlorine disinfectants -- may not be enough.
Studies show that certain disease-causing microbes are masters at playing hide-and-go seek with such chemical sanitizers. These bacteria can make their way inside the leaves of lettuce, spinach and other vegetables and fruit, where surface treatments cannot reach. In addition, microbes can organize themselves into tightly knit communities called biofilms that coat fruits and vegetables and protect the bacteria from harm. This kind of bacterial community can harbor multiple versions of infectious, disease-causing bacteria, such as Salmonella and E. coli.
Now, new findings from scientists at the U.S. Department of Agriculture suggest that irradiation, a food treatment currently being reviewed by the FDA, can effectively kill internalized pathogens that are beyond the reach of conventional chemical sanitizers.
Irradiation exposes food to a source of electron beams, creating positive and negative charges. It disrupts the genetic material of living cells, inactivating parasites and destroying pathogens and insects in food, including E. coli and Salmonella.
Using this technique on fresh and fresh-cut fruits and vegetables could provide a reliable way to reduce the numbers of foodborne illnesses reported each year in the United States, says Brendan A. Niemira, Ph.D., a microbiologist with the USDA's Agricultural Research Service in Wyndmoor, Pa., who directed the study.
"When bacteria are protected -- whether they're inside a leaf or inside a biofilm -- they're not going to be as easy to kill," Niemira says. "This is the first study to look at the use of irradiation on bacteria that reside inside the inner spaces of a leaf or buried within a biofilm."
The quantity of fresh fruits and vegetables in the United States has increased every year in the last decade. Unfortunately, the increase in consumption has been accompanied with an increase in the number of outbreaks and recalls due to contamination with human pathogens such as E. coli. Fresh fruits and vegetables carry the potential risk of contamination because they are generally grown in open fields with potential exposure to pathogens from soil, irrigation water, manure, wildlife or other sources.
"The spinach outbreak in the fall of 2006, in particular, raised questions about how these organisms survived the various treatments that are applied -- the rinses and the washes and things," Niemira says.
At the time, research had already demonstrated that pathogens like Salmonella and E. coli can be drawn into fruits after they've formed, and can migrate into them during fruit growth and maturation if the plant is exposed to them during pollination or in the irrigation water. But questions remained as to whether a penetrating process such as irradiation could kill a pest located inside a leaf.
To see how internalized sources of bacteria responded to various treatments, Niemira and his colleagues devised a way to pull bacteria into the leaves of leafy green vegetables. The scientists cut leaves of romaine lettuce and baby spinach into pieces and submerged them in a cocktail mixture of E. coli. The bacteria was pushed inside the leaves with a vacuum perfusion process. The leaves were then treated with either a three-minute water wash, a three-minute chemical treatment or irradiation.
After treatment, the leaves were suspended in a neutral buffer solution and crushed to recover and count the internalized bacteria. The study showed that washing with plain water was not effective at reducing the levels of the pathogen on either spinach or lettuce. The chemical treatment, a sodium hypochlorite solution, did not result in significant reductions of E. coli cells in spinach leaves, and an gave less than 90 percent reduction of E. coli in the romaine lettuce samples.
Ionizing radiation, in contrast, significantly reduced the pathogen population in both the spinach and the lettuce leaves. The level of kill was dependent on the dose applied, with reductions of 99.99 percent on romaine lettuce and 99.9 percent on spinach at the highest dose tested.
The researchers then conducted lab tests with biofilms to see how well different strains of Salmonella and E. coli, which were buried inside the biofilms, stood up to irradiation.
The biofilms that contained Salmonella tended to die more easily with irradiation, while those that were infected with E. coli were a bit more resistant, Niemira says.
"In the most resistant cases, we saw a difference of a few percent, but it was nothing at all compared to the resistance you might see if you were using a chemical treatment," he says.
The scientists now are conducting studies of biofilms on leafy green vegetables to better gauge how irradiation might work on plants in the field.
Niemira says it's still not clear if human pathogens can actually increase in population within plant tissues, or if they merely persist.
"This is an important question, because if the pathogens don't reproduce effectively within these protected spaces and stay below minimally infective population sizes, then the risk they pose to consumers is less," he says. "If they are able to reproduce inside, then they may increase to more dangerous levels."
Though some activist groups continue to speak against irradiation, consumer confidence in the application has grown steadily through the years as studies have shown its effectiveness in reducing pathogens that cause foodborne illnesses, says Christine Bruhn, Ph.D., who focuses on consumer issues in food safety and quality at the University of California at Davis.
"Sixty to 90 percent of consumers indicate that they would buy irradiated food when told of the benefits of the process and the endorsement of health authorities," Bruhn says.
She and Niemira have submitted a proposal to the USDA to further explore the applications of irradiation in leafy greens and to gauge consumer acceptance of this application.
Adapted from materials provided by American Chemical Society, via EurekAlert!, a service of AAAS.
So if you want healthy fruit, you need to have a nuclear power plan built near your town.
(I should really change my tagline before posting this endorsement of zombie movies.)
Oh no not this again. Irradiation was discussed in the 80’s and the scared of nuclear-xrays-cancer causing-crowd had a huge fit. History is such a comfort as you now know what to expect this go around, absolute hysteria and zero.
Irradiate Iran, do it for the children.
It’s amazing to me the Human race has survived for thousands of years eating these poisonous fruits and vegetables...my goodness, how did we ever get along without irradiation studies and such......./sarc
Wonder why this kind of science is believed by so many people who in turn, won’t believe the scientists about global warming being a natural event that goes from cooling to warming & back again & has been going on for centuries on this earth.
Wasn't Chernobyl and Three Mile Island enough for you horrible, evil people? Now you want to nuke our food?
/insane antinuke protester mode off.
I ate mangoes in 1991, which almost killed me. I thought that irradiation of fruit and meats was a sure thing. The problem is that there is no window of time or hubs of distribution which can do the job within the "just in time" systems of distribution we now rely on. The nation's food supply is about a week on perishables. That's it. Taking three days to route produce/meats to irradiation centers is just not possible.
During the anthrax scares Surebeam sold hundreds of irradiation units to the post office. Unfortunately they had a hard time getting them set up just right and ignited more mail into flames than anything else.
The USDA in Wyndmoor Pa. has had a fully functional irradiation chamber for foods since the 1980’s. That’s in suburban Philadelphia. Of course the residents who live all around the complex have no idea whatsoever. Until now that is.
Had = Has. Present tense.
So can we sue these turkeys if we get food poisoning?
I think the movie sold a lot of other people on soft drinks and candy bars.
In the 80’s husband ran a company in San Marcos, CA which used irradiation on wire. When the idea of irradiated food came out there was much hope that irradiation would help problems with meat and possibly fruit and veggies. Yes, locating irradiation machines close to food source could have been worked out especially at slaughterhouses.
Ten year’s since that discussion certainly could have found many advancements in the problems of location and machinery. Irradiation equipment has shriveled to nothing and it is a shame as some lives could have been saved.
As for the meats, a protest was cried @ 3 cents a pound. Many grocers signed on for ground beef at those prices, but the installations never took place due to inability to raise capital and some very questionable accounting practices on the part of Surebeam and Titan.
The above cartoon is from Mike Adams site NaturalNews.com.
The problem, as Mike sees it, and I think he's right, is not that irradiation makes the food more harmful by making it more radioactive or some such. The fear of radioactivity is just a paper tiger conveniently brought up just to justify ridicule of those who would oppose irradiation.
Rather, the problem is that irradiation destroys essential nutrients in the food, leaving us weaker and more susceptible to disease.
See Mike's article The Food Irradiation Plot: Why the USDA Wants to Sterilize Fresh Produce and Turn Live Foods into Dead Foods.
To quote briefly from this article:
Even a simple leaf of spinach contains hundreds of natural medicines -- phytonutrients that help prevent cancer, eye diseases, nervous system disorders, heart disease and much more. Every living vegetable is a powerhouse of disease-fighting medicine: Broccoli prevents cancer, beet greens cleanse the liver, cilantro removes heavy metals, celery prevents cancer, berries prevent heart disease and dark leafy greens help prevent over a dozen serious health conditions while boosting immune function and helping prevent other infections. But when you subject these fruits and vegetables to enough radiation to kill 99.9% of the pathogens that may be hitching a ride, you also destroy many of the phytonutrients responsible for these tremendous health benefits!
This means that while irradiating food may decrease outbreaks of food-borne illnesses, it will have the unintended consequence of increasing the number of people who get sick from other infections (and chronic diseases) due to the fact that their source of natural medicine has been destroyed. For many Americans, you see, salad greens are their one remaining source for phytonutrients. Given their diets of processed foods, junk foods and cooked foods, there are very few opportunities for these consumers to get fresh, phytonutrient-rich foods into their diet. And now the USDA wants to take that away, too, by mandating the irradiation of all fresh produce.
In the 80’s there were only two companies that manufactured irradiation equipment High Voltage Engineering and RDI. No longer in business. If the crying crowd had not been so vocal both of those companies would still be in business because they were innovators.
I worked a temp job in a research facility at Texas A&M that did this kind of irradiation on frozen hamburger patties (good idea if you like your burgers rare). The kind of irradiation they are talking about in the article is irradiating foods with what is essentially a giant electron gun (like the one in the back of a tube TV only it fills up a large part of a building), they don’t expose these foods to x-rays, gamma rays, or anything the would leave residual radioactivity in the food. You can think of it more like electrocuting the bacteria (not quite accurate, but close enough for this discussion) than killing them with x-rays.
OK Thanks. But if the word is irradiation it will bring out the howlers!! Once again ending what could save lives.
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