Most food is wrapped in plastic that is neither recyclable nor biodegradable. And, in some cases, plastics may leach harmful materials into food.
The researchers presented their work at the 252nd National Meeting & Exposition of the American Chemical Society (ACS) in Philadelphia. The event featured more than 9,000 presentations on a wide range of science topics.
Research leader Peggy Tomasula, D.Sc said that the protein-based films prevent food spoilage and could prevent food waste.
Casein better than starch
Researchers at the US Department of Agriculture are developing the film from casein, which they say is up to 500 times better than plastic at keeping oxygen away from food.
Because the edible film is derived from milk, it is biodegradable and sustainable.
No health issues
Responding to potential concerns over milk products being used as a film with respect to those who are lactose intolerant, Tomasula told DairyReporter that there is no lactose in the films, and the casein has less than 1% carbohydrates.
“We use casein as a model protein for studying the films, in the future, we would like to make them with other milk products. There is no health issue with the film. Since it contains milk protein though, it cannot be used to wrap or as a coating on fruits or vegetables; for example,” she said.
Adding citrus pectin
The researchers said their first attempt using pure casein resulted in a strong and effective oxygen blocker, but it was relatively hard to handle and would dissolve in water too quickly.
They made improvements by incorporating citrus pectin into the blend to make the packaging stronger, as well as more resistant to humidity and high temperatures.
After a few additional tweaks, the casein-based packaging looks similar to store-bought plastic wrap, but it is less stretchy. The edible material is made almost entirely of proteins.
Future in edible packaging
According to the researchers, nutritious additives such as vitamins, probiotics and nutraceuticals could be included in the future. As the product has little taste, they say, flavors could be added.
“The coatings applications for this product are endless,” Laetitia Bonnaillie, Ph.D., co-leader of the study, said.
“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.”
Potential for cereal
Because single-serve pouches would need to stay sanitary, they would still have to be encased in a larger plastic or cardboard container for sale on store shelves to prevent them from getting wet or dirty.
In addition to being used as plastic pouches and wraps, the casein coating could be sprayed onto food, such as cereal flakes or bars. Currently, cereals keep their crunch in milk due to a sugar coating.
The spray could also line pizza or other food boxes to keep grease from staining packaging, or serve as a lamination step for paper or cardboard food boxes or plastic pouches.
The US Food & Drug Administration recently banned the perfluorinated substances that used to coat these containers, so casein coatings could be a safe, biodegradable alternative.
Bonnaillie said her group is currently creating prototype film samples for a small company in Texas, and the development has garnered interest among other companies, too. She predicts this casein packaging will be on store shelves within three years.