Most foods at the grocery store come wrapped in plastic packaging. With concerns rising around the mass of non-recyclable, non-biodegradable waste coming from this, scientists are now developing a packaging film made of milk proteins that addresses these issues — and it is even edible.

The researchers presented their findings at the 252nd National Meeting and Exposition of the American Chemical Society (ACS) in August. According to Peggy Tomasula, D.Sc. lead researcher, the protein-based films are powerful oxygen blockers that prevent food spoilage and when used in packaging they could prevent food waste during distribution along the food chain.

To create an all-around better packaging solution, Tomasula and colleagues at the United States Department of Agriculture are developing an environmentally friendly film made of the milk protein casein.

These casein-based films are up to 500 times better than plastics at keeping oxygen away from food and, because they are derived from milk, are biodegradable, sustainable and edible.

Creating edible packaging

Some commercially available edible packaging varieties are already on the market, but these are made of starch, which is more porous and allows oxygen to seep through its micro holes. The milk-based packaging, however, has smaller pores and can thus create a tighter network that keeps oxygen out.

Although the researchers’ first attempt using pure casein resulted in a strong and effective oxygen blocker, it was relatively hard to handle and would dissolve in water too quickly. They made some improvements by incorporating citrus pectin into the blend to make the packaging even stronger, as well as more resistant to humidity and high temperatures.

After a few additional improvements, this casein-based packaging looks similar to store-bought plastic wrap, but it is less stretchy and is better at blocking oxygen. The material is edible and made almost entirely of proteins. Nutritious additives such as vitamins, probiotics and nutraceuticals could be included in the future. It does not have much taste, the researchers say, but flavourings could be added.

Endless coating applications

“The coatings applications for this product are endless,” says Laetitia Bonnaillie, Ph.D., co-leader of the study. “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.”

Bonnaillie says her group is currently creating prototype film samples for a small company in Texas, and the development has garnered interest among other companies, too. The group plans to keep making improvements, and she predicts this casein packaging will be on store shelves within 3 years.