USDA developing biodegradable, edible film made from casein

Researchers at the US Department of Agriculture (USDA) have developed an edible and biodegradable packaging film, which is made from the milk protein casein.

The new wrap differs from petroleum-based films, which are generally unsustainable, not biodegradable and detrimental to the environment because of the amount of plastic waste they create every year. They also offer superior performance to existing edible films, USDA said, because the packaging is much less porous and has a tighter network of microholes that is up to 500 times more effective at keeping oxygen away from food, in turn reducing spoilage.

The scientists found that early prototypes were hard to handle and would dissolve in water too easily, so they incorporated citrus pectin into the blend to make the packaging even stronger, as well as more resistant to humidity and high temperatures.

The casein-based packaging looks similar to regular plastic wrap but is less stretchy and better at blocking oxygen. Nutritious additives such as vitamins, probiotics and nutraceuticals could be included in the future, with USDA hoping that the invention will be made available in stores within the next three years.

In addition, the film is said to have little flavour, although extra flavourings could also be incorporated in the future.

But the use of the protein casein will make the edible packaging unsuitable to those with dairy intolerances.

The researchers have presented their work to the National Meeting & Exposition of the American Chemical Society.

“The protein-based films are powerful oxygen blockers that help prevent food spoilage. When used in packaging, they could prevent food waste during distribution along the food chain,” said research leader Peggy Tomasula.

And Laetitia Bonnaillie, co-leader of the study, added: “The coatings applications for this product are endless. We are currently testing applications such as single-serve, edible food wrappers. For instance, individually wrapped cheese sticks use a large proportion of plastic – we would like to fix that.”

In addition to being used as plastic pouches and wraps, the casein coating could be sprayed onto cereal flakes or bars to help improve texture retention when milk is poured on. The spray also could line pizza or other food boxes to keep the grease from staining the packaging, or to serve as a lamination step for paper or cardboard food boxes or plastic pouches.

Bonnaillie says the group is currently creating prototype film samples for a small company in Texas, and the development has garnered interest among other companies too.