Milk: food wrap of the future?

Much of the plastic packaging we see in the grocery store can be recycled, from egg containers, to milk jugs, to butter tubs. But what about that thin plastic film stretched around wedges of manchego in the cheese bin or the 16-ounce rib-eye in the chiller case?

It turns out that kind of plastic is tougher to recycle and might even be adding harmful chemicals to your food. Oh, and it’s not even good at doing what it’s supposed to do: prevent food spoilage.

Luckily, researchers are investigating alternative forms of food packaging — the kind you can eat.

U.S. Department of Agriculture researchers have discovered that a milk protein called casein can be used to develop an edible, biodegradable packaging film. The casein-based film is up to 500 times better than plastic at keeping oxygen away from food because proteins form a tighter network when they polymerize, the researchers found. It’s also more effective than current edible packaging materials made from starch and protects food products that are sensitive to light.

“Everything is in smaller and smaller packaging, which is great for grabbing for lunch, for school, but then it generates so much waste,” said Laetitia Bonnaillie, a USDA researcher who co-led the casein packaging research. “Edible packaging can be great for that.”

To produce a more practical packaging material, the team added glycerol and citrus pectin to the casein film, which is made by spreading a mixture of water and commercially available casein powder. Glycerol made the protein film softer, and citrus pectin added more structure to the film, allowing it to resist humidity and high temperatures better. Bonnaillie said the additives used by researchers also distinguish their packaging, because pectin is good for us.

One of the potential applications could be as a dissolving packet of dried coffee or soup. Instead of tearing the top off and pouring it out, you just drop the whole thing in hot water, and it dissolves, adding protein to boot. Another is as single-serve food wrappers that use large amounts of plastic for such products as cheese sticks.

Unless companies try finding their own applications of the packaging, it will be years before the USDA researchers can make it available, Bonnaillie said. She said they are at the very beginning of a process of finding applications for a product that has the potential to be “so much better than plastic.”