At the grocery store, most foods -- meats, breads, cheeses, snacks -- 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. And 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 it is even edible.
The researchers presented their work this week at the 252nd National Meeting
& Exposition of the American Chemical Society (ACS). ACS, the world's
largest scientific society, is holding the meeting in Philadelphia. It features
more than 9,000 presentations on a wide range of science topics. A brand-new
video on the research is available at http://bit.ly/ACSediblepackaging.
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. 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. 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 it is less stretchy and is better at blocking
oxygen. The material is edible and made almost entirely of proteins. Nutritious
additives such as vitamins, probiotics and nutraceuticals could be included in
the future. It does not have much taste, the researchers say, but flavorings
could be added.
"The coatings applications for this product are endless," says
Laetitia Bonnaillie, Ph.D., co-leader of the study. "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. 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. The U.S. Food & Drug Administration recently
banned the perfluorinated substances that used to coat these containers, so
casein coatings could be a safe, biodegradable alternative.