The Plastic Wrap of the Future Will Be Made Out of Milk

Deep inside a secure, high-tech government lab outside Philadelphia, a team of accomplished chemical engineers have been toiling for years on technology that could revolutionize multiple industries and the everyday lives of millions—or at least change the way school kids eat the snacks stored inside their superhero lunch boxes. Instead of peeling off the plastic wrap encasing their string cheese, they might soon be able to chomp the whole thing, wrapper and all—because instead of plastic, that wrapper will be made of milk.

The United States Department of Agriculture's Eastern Regional Research Center, located on a nearly five-acre campus in the leafy Philly suburb of Wyndmoor, is home to the Agricultural Research Service (ARS). Resembling a lush university, this location, one of four of its kind nationwide, employs around 200 people across multiple departments, each of which focuses on a specific field of consumption-based study—food safety, sustainable biofuels, and predictive microbiology. But I recently visited to learn about a specific project helmed by the Dairy and Functional Foods arm of the USDA-ARS.

Using isolated forms of casein—the most abundant protein found in bovine milk—researchers have developed an edible, sustainable, and powerful alternative to conventional plastic wrap, one that could positively impact America's dairy farmers and change the complexion of your supermarket cheese case.

Since the the innovation was formally announced at a conference this past summer, most media coverage has focused on the positive environmental implications—less plastic in landfills and the like. But that's a secondary storyline, at least according to the scientists. While the widespread use of casein film could definitely have a positive long-term impact on the planet, the USDA's immediate work is less about sustainability, and more about the nutritional possibilities of this technology. The people putting in the lab work are singularly focused on developing solutions benefitting both American dairy farmers and American consumers of dairy.

"One misconception was that this would be part of the packaging, and therefore not mentioned in the ingredients," says Dr. Laetitia Bonnaillie, a research chemical engineer at USDA-ARS. "That is not the case. This is going to be glued to the food, therefore part of the food. You eat it with the food."

This development came into focus around 2002, when Dr. Peggy Tomasula filed a patent for a process involving the use of high-pressure carbon dioxide to separate milk proteins. Tomasula began playing with the idea of developing thin-but-strong films built with casein, a versatile material that historically has been used to manufacture everything from buttons to industrial glue.

Listening sessions with dairy farmers—essentially business forums for those in the industry to share their top concerns—revealed that they were in need of solutions putting America's surplus of powdered milk to good use. Tomasula and her team then got to work testing an entirely new casein-based product. Odorless, flavorless and instantly dissolving—according to the scientists—the film is visually indistinguishable from the conventional cling wrap in your kitchen, but it protects and preserves food better than plastic and carries nutritional value to boot.

During my recent on-site walkthrough of the process, Bonnaillie and technician John Mulherin detailed what is currently a long and involved routine—one they ensure can and will be streamlined in the future.

The current process starts with sodium caseinate and calcium caseinate powders. After mixing these powders with deionized water and introducing natural additives like glycerol and pectin to the mix, the suspensions are degassed in a vacuum chamber and held in a refrigerator overnight to allow chemical bonds to start forming. The next day, the mixtures are spread on silicone baking sheets and cast into films, and from here can often sit for at least another week, as the molecular configuration of proteins tends to be unstable, requiring time to settle.

"It takes over a week just to make one series, so it's slow going and highly variable," says Bonnaillie, who, as a native of Aix-en-Provence, France, has a highly personal stake in all things involving cheese. "It took a few years to get some films that we liked to start wrapping foods with."

Bonnaillie and her team hope the finished products, which are stored in file folders inside a temperature-stable environmental chamber, will soon replace the plastic you'd normally trash after ripping open a fresh hunk of manchego—maybe as soon as three years from now, Bonnaillie ballparks. They have been testing the wrapping with blocks of conventional white cheddar, logging positive results in terms of shelf life—zero mold over a period of months, showcasing the wrap's efficacy in blocking oxygen. But it's the properties you can't register with the senses that make these prototypes so innovative.

In simple terms, the structure of these casein-based films blocks oxygen, the primary catalyst of spoilage, up to 250 times better than conventional plastic—so in addition to being edible and biodegradable, the packaging could lead to dramatic reductions in food waste. Plastic, however, is much better at keeping water away from the products it's protecting, meaning foods encased in casein film would be susceptible to H2O. This, then, would require any product protected by this film to be stored in a tough exterior package to protect against dirt and water.

It's difficult to tell at this point in the game whether eaters accustomed to discarding plastic packages will smoothly adapt to eating them—an odd, if digestively feasible, version of the Trident-with-the-wrapper-on trick we pulled as kids. Tomasula feels the task of normalizing this futuristic take on ready-to-eat ultimately lies with the companies who will eventually incorporate it into their product lines.

Down the line, Bonnaillie, Tomasula and company can see their development, and variations therein, implemented into products in a number of ways beyond just well-preserved Polly-O. Since the film is soluble and can be imbued with vitamins, minerals, and flavorings, it could work for soups and beverages—picture a broth-flavored packet filled with veggies that turns into an instant cold remedy when dropped into boiling water, or an instant coffee packet with the creamer and sugar built right in. For now, however, the researchers are careful to note their films will be applied only to products that contain dairy and are clearly marked as such, considering concerns from those with milk allergies.

Regardless of how it grows, the casein film is not a cling-wrap killer—even if it does lead to macro-level decreases in its use down the line. "You can't replace that [plastic wrap] market," confirms Tomasula. "We're looking at this as more of a food product."

There are definite non-food applications to the casein film, too, but in classic government parlance, Tomasula can't go into details. She can say, however, that plenty of people have reached out thus far. "It wouldn't be a stretch to say we've heard from everyone," says Tomasula, who adds that they've also been approached by manufacturers interested in scaling up their film-making process. "A lot of companies see the potential for it." Maybe, down the line, kids will be scarfing down their string cheese and the superhero lunchbox it comes in, too.