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Ozone reduces fungal spoilage of fruits and vegetables

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April 12, 2011

Scientists have discovered that treating fresh produce with ozone increases its resistance...

Scientists have discovered that treating fresh produce with ozone increases its resistance to fungal infection (Photo: Noel McKeegan/Gizmag)

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We've all done it – thrown out fruit or vegetables because they went rotten. Fungal contamination is the most common cause of spoilage of fresh produce, with an estimated 30 percent of harvested fruit and veggies falling victim to it. Countermeasures currently including synthetic fungicides and pre-package sanitation treatments involving the use of chlorine or bromine. Now a team of scientists from Britain's Newcastle University have discovered that much more effective and human-friendly results can be obtained by treating produce with ozone.

Led by microbiologist Dr. Ian Singleton and plant biologist Prof. Jerry Barnes, the Newcastle researchers experimented with storing fresh fruit such as strawberries, tomatoes, grapes and plums in an environment that contained low levels of gaseous ozone. Not only was the production of fungal spores substantially reduced, but lesions on already-infected fruit became less visible. After eight days in the environment, the produce showed almost 95 percent less spoilage than would otherwise have occurred – depending on the specific fruit and pre-existing levels of infection.

It was also found that tomatoes exposed to ozone became more fungus-resistant, even once they were removed from the ozone gas. Exposed tomatoes were 60 percent less likely to develop fungal lesions, potentially boosting their shelf life by two to five days. While the scientists can't explain exactly what forces are at work behind the reaction, they suggest that some sort of memory- or vaccination-like effect is likely taking place. They are now looking into the specific amounts of ozone and lengths of exposure that work best for individual types of fruit and vegetables, as too much ozone can also cause spoilage.

Dr. Ian Singleton in the ozone lab

"There are public concerns over pesticide residues on fresh produce" said Singleton. "Ozone is a viable alternative to pesticides as it is safe to use and effective against a wide spectrum of micro-organisms. Importantly, it leaves no detectable residues in contrast to traditional methods of preserving fresh produce."

In the case of the tomatoes, the amounts of ozone involved were said to be similar to those which the fruit would be exposed to outside on a sunny day.

The research was recently presented at the Society for General Microbiology's Spring Conference in Harrogate, England.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
7 Comments

As a fresh peach farmer in California we have been using ozone to control fungus for at least 5 years. Maybe the fellow in article has reinvented the wheel.

pluotfarmer
13th April, 2011 @ 09:01 am PDT

I worked with a company in 2010 that has been building ozone generators for this purpose for the last 5 years. It's not new, the tech has been around for at least 15 years, at least here in California... Ozone also keeps fruits from ripening...

Chris Maresca
13th April, 2011 @ 10:14 am PDT

Out of Africa there is always something new. See http://www.olgear.com/index.html

Nols Smit

South Africa

Facebook User
13th April, 2011 @ 11:51 am PDT

In the 1940s my grandfather had a machine, about the size of a bread box, with spiral tubing on top (kinda like neon tubing). He ran it for a few hours each day in his home. The tubing gave off a purplish glow and it made the air smell metalic. I was too young then to ask any questions about it, but I think it was supposed to have some "health" benefits. He called it his "Ozo machine".

C. O. Slavens
13th April, 2011 @ 02:59 pm PDT

We've been selling ozone generators for years in Asia to the F&B industry. Restaurants, kitchens, wholesalers, produce farmers... all are using ozoneated water to keep foods, meats, seafood, poultry, vegetables etc fresh longer and to kill Salmonella, E.Coli and Coliform bacteria. Ozone also kills mold and mildew, fungus as well which means expensive and perishable berries like Raspberries will last days longer. Other outlets are simply ozoneating the air in their food chillers and kitchens to eliminate airborn pests, germs, mold, fungus and mildew.

When used properly, ozone is a wonderful tool in the food industry, or hospitality industry.

Paul Horizonhills
13th April, 2011 @ 05:04 pm PDT

Ozone is poisonous to humans. They may as well have used carbon monoxide gas or irradiation to save their fruit. Oh yeah - except that everyone *knows* those are dangerous, and takes suitable protective steps when using them! Check back here in a decade or two when the lawsuits from sick fruit-workers start pouring in...

christopher
13th April, 2011 @ 06:16 pm PDT

@christopher you are confused...

Ozone (O3) is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic species O2. Ground-level ozone is an air pollutant with harmful effects on the respiratory systems of animals. On the other hand, ozone in the upper atmosphere protects living organisms by preventing damaging ultraviolet light from reaching the Earth's surface. It is present in low concentrations throughout the Earth's atmosphere. It has many industrial and consumer applications as well as being used in ozone therapy.

Theunis Greyling
14th April, 2011 @ 08:11 am PDT
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