But won't you have to wrap the wrap?

By Peg Herring
Wednesday, 06 October, 2004

Yanyun Zhao, food technologist at Oregon State University, coats fresh strawberries with a new antimicrobial film.

What do you get when you cross an egg white with a crabshell? You get a thin film that prevents food from spoiling and can be eaten along with the food that it wraps.

It can even be fortified with vitamins and minerals so the food and the film together make a more nutritious fare.

This super packaging is the latest technology from Oregon State University's Department of Food Science and Technology. The film combines two key ingredients: a fibre from shellfish (chitosan) and a protein from egg whites (lysozyme). Its discovery combines the ingenuity of two OSU researchers: Yanyun Zhao, a food technologist and specialist in value-added products, and Mark Daeschel, a microbiologist and specialist in food safety.

Working with postdoctoral research associate Su-il Park, Zhao and Daeschel began experimenting with ways to combine lysozyme and chitosan to create an anti-microbial food wrap. The product they have developed looks like familiar sandwich wrap, but delivers much more.

Because it is made entirely from food products, the wrap is edible. It's so thin that it doesn't interfere with the texture of the food it covers. And it is made from powerful natural antimicrobials, so it keeps fresh food from spoiling. A patent application has been filed for the technology, which has many potential applications.

"You can use it as a film to wrap foods or you can use it as a spray or dip to coat foods," Zhao explained. "And you can enrich the film or coating with extra nutrients, such as vitamin E and calcium, to boost the nutritional value of the food."

For several years, Zhao has been experimenting with chitosan to develop thin protective coatings for perishable fruits and berries. Chitosan is a key ingredient in crabshells and shrimp shells, the tough exoskeleton that serves as protective armor. She confirmed that the natural polymer in chitosan inhibits the growth of microbes that cause rot in fresh berries and other foods.

At the same time, Daeschel has been experimenting with lysozyme as a natural preservative in beer and wine. Daeschel found that the egg white protein was just as effective as chemical sulfites in preventing unwanted microbial growth, without compromising the taste or quality of the product.

The scientists realised that their two key ingredients each have particular antimicrobial properties that could enhance each other if combined.

"These are naturally occurring ingredients," said Daeschel. "The chitosan is derived from seafood shells, much of which is otherwise wasted. This is a good example of adding value to an existing product."

The next challenge for Zhao, Daeschel and Park will be to develop practical applications for their super food wrap. The possibilities extend to packaging for ready-to-eat meats such as hot dogs, sausage and luncheon meat; packing films for cheese slices, blocks and sticks; and coatings for sliced fruits and vegetables that are highly perishable.

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