Farmers don't always consider how their food will be handled and packaged once it leaves the farm, but the end consumer cares how that hamburger patty is protected in the store. Or how the cheese or fruit is kept free of airborne pathogens. It's a hot topic in food production circles, and Oregon State University is a leading innovator in food wrap development.

That's news, because recently two researchers came up with a new antimicrobial wrap that's also edible. Yanyun Zhao, a professor of food science at Oregon State University. led the study into the new wrap. She has a long record of developing innovative food wraps, including a patented chitosan-lysozyme composite film-coating technology for food; a coating for fish fillets using chitosan and fish oil; and an edible coating and film made from the discarded pulp of crushed winegrapes that's used for fruits and vegetables.

Edible wrap for range of foods
This time out, Zhao and colleague Jooyeoun Jung have created a wrap that could eventually be used to protect a range of foods. The product is edible and has antimicrobial properties. Zhao and her team used two key ingredients to create the film.

The first is chitosan, a fiber derived from crustacean shells — a material she has worked with in the past.

The second is a cellulose nanofiber originally extracted from wood pulp.

The team's findings were published online in the journal LWT-Food Science and Technology. Zhao explained that her team put together two unique materials to enhance food packaging functionality while also solving some challenging problems for the industry.

Edible films are not a new idea, but current materials dissolve when exposed to water. For packaged foods with high water content or wet surfaces — such as meat — that can be a problem.

Cellulose nanofiber holds up when exposed to water; it doesn't protect against bacteria, however, that can cause foodborne illness, or oxidation — which can lead to deterioration of food products. Chitosan, an ingredient in crab and shrimp shells, acts as an antimicrobial and an antioxidant.

Zhao tested the new product with fresh beef patties in the lab and combined the strengths of both fibers. Wrapped around the patties, the film inhibited the growth of bacteria E. coli and listeria, and prevented surface moisture transfer between layered patties.

Stand-alone packaging potential
Noted Zhao: "We improved water resistance, antimicrobial functionality and mechanical properties, so the film has broad applications as stand-alone films for packing food with high water content, or as coatings for food with wet surfaces." She added that this film could replace non-biodegradable waxed papers or other synthetic polymers used in meat packaging.

More study is needed to validate application in other foods; and while cellulose nanofiber and chitosan are prepared from natural sources, for food usage and human consumption they need approval to obtain a "generally recognized as safe" label from the U.S. Food and Drug Administration.

Source: Oregon State University