AN EDIBLE PROTEIN film made from soybeans can help protect refrigerated and pre-cooked ready-to-eat food from dangerous bacteria.

Navam Hettiarachchy, University of Arkansas Division of Agriculture food scientist, has learned how to produce edible films from soybean proteins that can be coated right on food products or used in place of plastic wrap for prepackaged foods. These films can be impregnated with antimicrobial agents that inhibit growth of bacteria such as Listeria monocytogenes.

“Soy protein films have the potential to meet a demand for biodegradable packing material, and these films can function as carriers of antimicrobials that help protect against food-borne illnesses,” Hettiarachchy said. “We're trying to learn the properties of protein films that will work best as carriers for release of antimicrobials that will inhibit pathogens and extend shelf life of packaged foods.”

Two of the most important of these characteristics, she said, are hydrophilic and hydrophobic properties, or their ability to either dissolve or resist dissolving when in contact with water.

“We incorporated nicin, a bacteriocin with inherent antimicrobial qualities, into edible films,” Hettiarachchy said. UA researchers Mike Johnson and Marlene Janes had already shown nicin to be an effective antimicrobial wrapper when used in food-coating films.

Bacteriocins are digestible proteins produced by safe bacteria, which grow and survive in part by inhibiting the growth of other harmful bacteria. Nicin was added to solutions in different ratios to produce protein films with varying resistance to dissolving in water.

The films are applied to foods either by wrapping them in a dry film or by spraying them with a liquid that dries into a protective coating. Because they are edible and have no effect on flavor, they can be prepared and eaten with the food, leaving nothing to remove and throw away.