Think about the food you have sitting in your refrigerator right now: the blocks of cheese, the packages of apples, the cartons of eggs. Chances are that more than a few of those items are wrapped in plastic, and while some of those materials are recyclable, certain kinds of plastic food packaging — the thin film of plastic used to wrap cheeses or meats, for example— can’t be. That creates a stream of non-recyclable, non-biodegradable, fossil fuel-sourced waste that ultimately ends up adding to the 20 million tons of plastic waste floating around the ocean, not to mention landfills. What’s worse, that type of plastic wrapping doesn’t actually help keep food from spoiling, and might actually imbue food with harmful chemicals.
Luckily, researchers from the USDA have devised a different way to package things like meat, bread, and cheese. Instead of using plastic, they’ve developed an edible, biodegradable packaging film made of casein — a milk protein — that can be wrapped around food to prevent spoilage.
The United States produces a lot of milk, but milk consumption has been on the decline for years. So the USDA has been working for decades to find a way to take that excess milk — usually stored in powder form — and create something usable with it. Laetitia Bonnaillie, the principal investigator on the project, told ThinkProgress that the USDA has been working on creating food packaging from leftover milk products for decades. But it was only in the last few years that researchers cracked the code for making casein-based films competitive with plastic-films.
The biggest problem researchers faced with casein-based films, Bonnaillie explained, is that casein is extremely sensitive to water — a serious problem when you’re trying to create a product that is supposed to keep food sealed and dry.
“They are proteins, which love water, and they soak up moisture in the air,” Bonnaillie said. So the team at USDA decided to try adding pectin to the mixture, which Bonnaillie said acts like “a fishnet around the casein particles, to hold them in place.”
“The casein-based film is 250 times more effective at blocking oxygen than traditional plastic film.”
Adding pectin to the casein mixture created a film that, while still more sensitive to moisture than plastic, did not immediately dissolve in water or areas with humidity. Moreover, the casein-based film was actually more effective at blocking oxygen than plastic — 250 times more effective, according to Bonnaillie’s measurements. That keeps food from oxidizing and going stale, and also slows down the growth of bacteria.
“Number one product you want is a strong film because if it is too fragile there is no packaging you can make. But you also want it to be a good packaging, and be a good barrier against oxygen and moisture,” Bonnaillie said. “These are qualities that plastic is not good at. It does not block oxygen or light very well.”
There are still some issues associated with the casein-based packaging. Because it is moisture sensitive — and because one of the selling-points is that it is edible — the packaging can’t be used alone on store shelves, yet. In order to keep the packaging both stale and sanitary, Bonnaillie explained that the packaging would need to be used in conjunction with another, secondary layer of packaging. And while that might seem like it would just create more waste, Bonnaillie said that many products already use two layers of packaging —the plastic bag inside of a paper box, for instance. Bonnaillie also suggested that the casein-film could be used to make single-serving packaging for items like a soup or coffee, that, when dropped into hot water, would dissolve completely. The added benefit, she said, would be that the casein-film, when dissolved, would add protein to the food, making it more nutritious.
And it’s not just protein that could be added by the casein-film.
“Proteins are very good at encapsulating materials, so you could add other nutrients to it,” Bonnaillie said. Things like probiotics, or vitamins, could be added to the casein-packaging, creating a kind of single-serving coffee packet that, when dropped in hot water, would give you coffee with a side of probiotics — without all of the plastic.
“The consumer is more and more interested in saving the environment while also optimizing their nutrition.”
Beyond food packaging, Bonnaillie said that the casein-based film could be sprayed directly onto food — or directly onto packaging — to create a moisture resistant barrier or add nutrients. Bonnaillie explained that, in tests, cereal flakes sprayed with the casein protein retained their crunch and were much stronger than cereal flakes sprayed with sugar, which is the traditional method producers use to make sure that cereal flakes don’t immediately turn soggy upon contact with milk. If nutrients were added to the casein before it was sprayed on the cereal, then Bonnaillie argued that it would be a more effective, and much healthier alternative to spraying with sugar.
Bonnaillie also said that her team has tested spraying the protein on pizza boxes as a grease repellent. Earlier this year, the U.S. Food and Drug Administration banned the use of perfluorinated chemicals as lining in pizza boxes, due to concerns over potential toxicity — Bonnaillie suggested that manufactures could use the casein-protein in its place.
Though the technology is still in its early stages, Bonnaillie said that, with the right industry partners, consumers could see packaging on the shelves in as little as a year. And while the cost of the material will almost certainly, at least at first, be higher than traditional plastic packaging, Bonnaillie hopes that both companies and consumers will see the benefit in packaging that is both more eco-friendly and potentially healthier.
“The consumer is more and more interested in saving the environment while also optimizing their nutrition,” she said. “There is definitely interest in this.”