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'Killer paper' could prolong shelf life of foods

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January 19, 2011

Scientists have coated paper with silver nanoparticles, to create a 'killer paper' packagi...

Scientists have coated paper with silver nanoparticles, to create a 'killer paper' packaging that could lengthen the shelf life of foods (Photo: Robin)

Silver is a known killer of harmful bacteria, and has already been incorporated into things such as antibacterial keyboards, washing machines, water filters, and plastic coatings for medical devices. Now, scientists have added another potential product to the list: silver nanoparticle-impregnated “killer paper" packaging, that could help keep food from spoiling.

Led by Aharon Gedanken from Israel’s Bar-Ilan University, the team discovered that paper could be covered with silver nanoparticles through the application of ultrasonic radiation – a process known as ultrasonication. It involves the formation and subsequent collapse of acoustic bubbles near a solid surface, which creates microjets that throw the desired nanoparticles onto that surface. To the team’s knowledge, this was only the second time that ultrasonication had ever been attempted on paper.

Unlike previous attempts at creating antibacterial paper, this one-step method was reportedly quite effective, and produced a smooth, homogenous, long-lasting coating. By varying the nanoparticle concentration and the application time, the thickness of the coating could be varied as needed. When exposed to E. coli and S. aureus bacteria, both of which cause food poisoning, the paper killed them all off within three hours.

The scientists stated that the ultrasonication process could also be used to apply other nanomaterials to paper, which could be used to tweak its hydrophobicity, conductivity, or texture.

While the addition of ionic silver to foods has been used in the past to ward off bacteria, the paper would reportedly serve as a longer-term solution, as it would act as a slow-release reservoir for the silver. Germany’s Fraunhofer Institute for Process Engineering and Packaging has previously looked into the use of sorbic acid-coated plastic as an antibacterial food wrap.

The killer paper research was recently published in the journal Langmuir.

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
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6 Comments

Gamma irradiation is cheaper and easier.

Eideard
19th January, 2011 @ 04:51 pm PST

OK seriously, this is just silly. There are bacteria all around us. COOK THE FOOD..

Michael Mantion
20th January, 2011 @ 06:21 am PST

This sounds like a really bad idea - equally as bad as using silver nanoparticles in washing machines ! When these particles appear, as they inevitably will, in our environment, they are going to kill a lot of living things necessary, among other things, to our own welfare. When are we humans going to learn that not all disputes should be settled by killing our adversaries - whether fellow humans or bacteria ?!!...

Henri

mhenriday
20th January, 2011 @ 06:33 am PST

Just a few immediate questions in response:

-Is the silver retrievable via recycling of the papers? It is a limited resource after all.

-Or will we just flush it all back into the ecosystem as highly mobile new toxin (remember we, and all other animals require healthy populations of bacteria in our guts, on our skins, in our soils... while plants need them in their roots, also in the soil....) ?

- Would this not just allow even sloppier food management from industry and retailers, convinced the silver will magically protect foods from overlong storage and improper conditions and handling?

-Is the bacteriacidal action confined to where the food meets the paper? What about inside the food? Can we expect to find a new "toxic shock" equivalent where food which appears clean on the surface harbours thriving colonies of pathogens and decomposers in its interior?

- I can see how in some instances, extending shelf life and securing shelf-sanitation would be a boon, but face it, the biggest market will not be home owners in places with no refrigeration; it will be bigger distribution companies. Does this not fuel the opposite of what we now need to build better food security? Locally produced and consumed foods will mostly not have the worries of shelf life.

Facebook User
20th January, 2011 @ 08:04 am PST

I was going to post concerns about the consequences of this technology as well, but mhenriday and Facebook User both expressed them perfectly. What happens if some of the particles get on the food and then into the consumer's gut?

Unless the nanos can be engineered to ONLY kill specific bad bacteria like e-coli, AND to not get into the environment at large, there is no benefit here.

Facebook User also precisely described who will really benefit from it - Big Food Business' bottom lines.

Elizabeth Hagan
20th January, 2011 @ 12:49 pm PST

Time to buy more SLV, the silver exchange traded fund... up 100% since it's lows in 2008.

I'm a scientist first, but I also make money in the stock market... and reading articles like this is just one of many resources to help with the due diligence required for investing smartly.

Cheers,

Doc R

Matt Rings
20th January, 2011 @ 04:32 pm PST
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