Still hungry? Eat the packaging

At the supermarket, plastic packaging is ubiquitous. Not only does this create a lot of non-recyclable, non-biodegradable waste, but thin plastic films are not great at preventing spoilage. Some plastics are even suspected of leaching potentially harmful compounds into food.

A new packaging film is currently in development that will address these issues — and it is even edible.

Research leader Peggy Tomasula, D.Sc and colleagues at the US 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.

Protecting food from spoilage

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 microholes. The milk-based packaging has smaller pores, creating a tighter network that keeps oxygen out.

“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 Tomasula.

The researchers’ 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 incorporated 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 said, but flavourings could be added.

Multiple applications

“The coatings applications for this product are endless,” said Laetitia Bonnaillie, PhD, 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.”

In addition to being used as plastic pouches and wraps, this casein coating could be sprayed onto food, such as cereal flakes, to help cereals keep their crunch in milk without the use of a sugar coating. The spray could also line pizza or other food boxes to keep the grease from staining the packaging, or to serve as a safe, biodegradable lamination step for paper or cardboard food boxes or plastic pouches.

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. The group plans to keep making improvements, and she predicts this casein packaging will be on store shelves within three years.

The research was presented at the 252nd National Meeting & Exposition of the American Chemical Society (ACS). A video on the research is available here.