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Here’s a Food Wrapper You Can Eat

Made from milk protein, it not only keeps food from spoiling, but it also could keep a lot of plastic out of landfills

The casein film can either be used as wrappers, like this, or it can be sprayed onto food. (USDA)
smithsonian.com

Consider the cheese stick. It is not a beautiful food. Nor is it particularly healthy. It’s about as prosaic as snack food gets.

Yet in the packaged version that ends up in so many kids’ lunch boxes, each cylinder of mozzarella or cheddar is individually wrapped, like a high-end truffle. And, every day, thousands of those little pieces of plastic wrap are thrown in the trash.

But maybe not for long.

Two researchers at the U.S. Department of Agriculture (USDA) have developed a film made from a milk protein that can be eaten with the cheese. Which means that it may not be too long before we have a wrapper we can eat—one that’s also healthy. Edible plastic exists, but it’s largely made of starch, not protein.

“The benefit,” says Peggy Tomasula, one of the lead researchers, “is that it can be consumed with the food so it gets rid of one layer of packaging, like with individually-wrapped cheese sticks. It also gives you the opportunity to add vitamins or minerals or ways to block light damage to the food. And, you can add flavors. If you wanted to add a strawberry flavor to something, you can embed that in the film.”

It’s a wrap

The key component in the innovative packaging is casein, a group of milk proteins with high nutritional value. Tomasula has been researching casein since 2000, and actually created a new version of the protein using carbon dioxide. She noticed that it wasn’t very soluble in water, and that made her believe it might be used to make a film coating that could extend the shelf life of dairy foods.

Tomasula kept exploring the potential of this research and when another scientist, Laetitia Bonnaillie, joined the USDA team, Tomasula asked her to see if dry milk could be used to produce the film. That would also allow them to make use of surplus milk powder during times when dairy farms are producing too much milk. Bonnaillie also focused on refining the product by making it less sensitive to moisture and improving the process by which the film was made so it could be more uniform and commercial.

Last week, at the annual meeting of the American Chemical Society, they announced the results of their efforts—edible, biodegradable packaging. The casein film could either come in sheets—not unlike plastic wrap—or be sprayed on as a coating. And, it’s been found to be significantly more effective at blocking oxygen than ordinary plastic wrap, so it can protect food from spoiling for a much longer period of time.

There would be some limitations, at least initially. “This would mostly be for dairy products or foods that would likely be used with dairy, like cereal,” says Tomasula. “We wouldn’t put this on fruits and vegetables in a market. You couldn’t do that because of milk allergies. There would have to be labeling to let people know it’s milk protein.”

Also, this wouldn’t mean that all packaging would be eliminated for cheese and other dairy products. They would still need to be covered in some way, in a box or packet to keep the food from getting dirty or exposed to too much moisture. But dispensing with the individual wrapping around each food item could mean a lot less plastic would end up in landfills. By some estimates, it can take as long as 1,000 years for plastic to degrade. And, unfortunately, less than a third of the plastic Americans throw away actually gets recycled.  

The idea, said Bonnaillie, is to create different versions of the casein film. One might be very soluble, making it better suited for a product you dissolve in water. Another could be considerably less soluble so it would be more resistant to moisture and work better as protective packaging.

“We are trying things with the extremes,” she says. "We’ve just started exploring applications. There are many more things we can do.”

Say so long to sugar?

For instance, instead of tearing open a paper container to make instant coffee or soup, you could just drop a casein packet of the ingredients into water where everything would dissolve. Plus, extra protein would be added.

But food companies might actually prefer a spray version of the product. “That way they could store a mixture of the particular milk proteins in water, and then make the coatings and spray them on when they’re processing the food,” says Tomasula.

One possibility would be to spray the protein film on cereal, which generally is coated with sugar to keep it crunchy. “It could be fat-free—a healthier way to replace a process that’s now largely done with sugar,” says Bonnaillie.

Tomasula adds: “We’re hoping that for something like meal replacement bars we can make the edible wrapping taste like chocolate. We could combine the ingredients together and provide a little more nutrition.”

Tomasula and Bonnaillie say they’ve already been working with some companies, and believe their edible packaging could be on the market within three years.

Another good sign: Since last week’s announcement, they’ve been contacted by what they describe as “two major companies.”

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