PACKAGING FILM AS A STERILE ZONE

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PACKAGING FILM AS A STERILE ZONE
25 October 2004 - Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.

No one wants food that has gone mouldy – least of all when they have only just purchased the product. But consumers are not exactly wild about food preservatives either. Packaging researchers are now introducing coated films to fight the battle of the bacteria.

At first glance, food packaging and an operating theatre don’t have much in common. But when you look at the elaborate procedures that are used in sterilising packaging materials, the operating theatre analogy is not so far-fetched after all. Bacteria settle themselves at the exact spot where the foodstuff touches the packaging, and multiply rapidly from there. To put paid to the unwanted settlers, film-packaged foodstuffs often contain added food preservatives such as benzoic or sorbic acid. However, discerning consumers prefer to have as few additives as possible in their food.

This is why scientists at the Fraunhofer Institute for Process Engineering and Packaging IVV, working in the Alliance for Polymer Surfaces POLO, have opted for a different way of scaring off the moulds and microbes. Instead of adding preservatives to the food, they coat the packaging film with them.

“This places the substances directly at the surface of the foodstuff, which is where they need to act,” explains group leader Dieter Sandmeier. “In that way we can cut food preservatives to a minimum.” The coating layer is applied using special techniques and materials based on substances such as Ormocers.

These plastics contain elements of inorganic glass and organic polymers. “We have managed to develop films that can protect solid products from attack by all kinds of bacteria,” Sandmeier is pleased to report.

Films like this are not good enough when it comes to protecting liquid foods like milk, however. Because in this case the food preservatives introduced do not remain on the surface as they would on cheese or sausage. They spread through the entire product and are heavily diluted. Packaging materials for liquids are therefore sterilised with hydrogen peroxide, for example, before being brought into contact with foodstuffs.

But this complex procedure is performed at temperatures in excess of 70C, which is too high for certain plastics such as PET. The IVV researchers have now taken a leaf out of the medical technicians’ book. They sterilise medical instruments with plasma, an ionised gas. There is just one drawback: the treatment takes at least half an hour, or even up to one and a half hours – far too long for an industrial bottling process. The scientists have now optimised the process so that it only takes one to five seconds.

In this way they have no problem complying with environmental protection regulations, and energy consumption can be reduced by a factor of up to 1,000.

Dr Dieter Sandmeier
+49 8161 4 91 6 05
dieter.sandmeier@ivv.fraunhofer.de

http://www.fraunhofer.de

About: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
The Fraunhofer-Gesellschaft undertakes applied research of direct utility to private and public enterprise and of wide benefit to society. Its services are solicited by customers and contractual partners in industry, the service sector and public administration. The Fraunhofer-Gesellschaft maintains over 80 research units at more than 40 different locations throughout Germany. A staff of some 12,700, predominantly qualified scientists and engineers, works with an annual research budget of over one billion euros. Of this sum, more than € 900 million is generated through contract research. Two thirds of the Fraunhofer-Gesellschaft’s contract research revenue is derived from contracts with industry and from publicly financed research projects. The remaining one third is contributed by the German federal and Länder governments, as a means of enabling the institutes to pursue more fundamental research in areas that are likely to become relevant to industry and society in five or ten years’ time.

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