At the grocery store, most foods come wrapped in plastic packaging. Not only does this create a lot of non-recyclable, non-biodegradable waste, but thin plastic films are not great at preventing spoilage either. Furthermore, some plastics are suspected of leaching potentially harmful compounds into food. To address these issues, scientists are now developing a packaging film made of milk proteins — and believe it or not, it’s even edible.
“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,” research leader Peggy Tomasula, D.Sc., said in a recent article.
And spoiled food is just one issue. Current food packaging is mainly petroleum-based, which is not sustainable. It also does not degrade, creating tons of plastic waste that sits in landfills for years.
To create an all-around better packaging solution, Tomasula and colleagues at the U.S. 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.
The article explains that 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, however, has smaller pores and can thus create a tighter network that keeps oxygen out.
Although the researchers’ first attempt using pure casein resulted in a strong and effective oxygen blocker, it was relatively hard to handle and would dissolve in water too quickly. Because of this they made some improvements by incorporating 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 the article states it is less stretchy and is better at blocking oxygen. Made almost entirely of proteins, the material is also edible. Nutritious additives such as vitamins, probiotics and nutraceuticals could be included in the future, and while it does not have much taste, the researchers say, flavorings could be added.
“The coatings applications for this product are endless,” Laetitia Bonnaillie, Ph.D., co-leader of the study said. “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.”
Because single-serve pouches would need to stay sanitary, they would have to be encased in a larger plastic or cardboard container for sale on store shelves to prevent them from getting wet or dirty.
In addition to being used as plastic pouches and wraps, this casein coating could be sprayed onto food, such as cereal flakes or bars the article explains. Right now, cereals keep their crunch in milk due to a sugar coating. Instead of all that sugar, manufacturers could spray on casein-protein coatings to prevent soggy cereal. The spray also could line pizza or other food boxes to keep the grease from staining the packaging, or to serve as a lamination step for paper or cardboard food boxes or plastic pouches.
Bonnaillie said that her group is currently creating prototype film samples and if all goes according to plan, she predicts this casein packaging will be on store shelves within the next three years.
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