Packaging is essential to the preservation and distribution of many types of food, but it often includes plastic, whose waste is already polluting the planet too much, threatening wildlife and contaminating drinking water and soil. Now the researchers say they have developed a non-toxic, biodegradable and antimicrobial food grade coating This could reduce food waste and foodborne illness without adding plastic to the environment. New research shows that this material can be effectively sprayed onto individual foods such as fruits or vegetables. Removing it is as easy as rinsing it off with water.
Protecting food from bacteria and other microorganisms reduces spoilage, which is a major factor in food to be thrown out. And this kind of waste is root cause of world hunger: Every year about one third food produced all over the world is thrown away. This is not the only reason to protect foods from germs – some microorganisms are also sources of disease, including listeriosis and listeriosis. coli poisoning. Foodborne illness causes more 420,000 estimated deaths worldwide annually.
Unfortunately, packaging food to preserve it also greatly increases environmental plastic. “Food packaging is definitely enemy number one when it comes to plastic pollution,” says Vin Kauger, an environmental scientist at the Moore Institute for Plastic Pollution Research, who was not involved in the new study. “All over the world, we see that food packaging is the most common plastic material in the environment.” While the new coating will only replace some of the existing packaging — it won’t affect some of the biggest offenders like water bottles and coffee cup lids — Kauger says any step to reduce plastic pollution is a good step.
Plastic may remain in the environment for a long time, and possibly forever, but the new coating is biodegradable. This is due to its main ingredient: pullulan, a dietary fiber that is “Generally Recognized as Safe” (GRAS) by the U.S. Food and Drug Administration. The coating also includes the natural antimicrobial agents citric acid and thyme oil, as well as a bacterially derived compound called nisin, all of which are considered safe for human consumption in appropriate amounts. This is described in a new study published this week in Nature Food.
The researchers used a manufacturing system called focused rotary jet spinning, or FRJS, to produce antimicrobial-impregnated fibers for food applications. Harvard University bioengineer and study co-author Huibing Chang compares the FRJS system to a cotton candy machine that spins melted sugar rapidly by passing it through small holes to produce thin threads that can be wrapped around a paper cone. FRJS also creates a focused stream of thin fibers (in this case made from pullulan, not flavored sugar) that can be wrapped around a food item like an avocado. But FRJS, developed by study co-author and bioengineer Keith Parker at Harvard Lab, where Chang is a researcher, was not originally intended for food. “When we created this technology, we used it for tissue engineering,” Chang says. For example, he explains, FRJS played a role in his previous work creating 3D models of some structures of the heart.
The researchers tested the coating on avocados because these fruits are particularly prone to uneven ripening and post-harvest rot. The study found that once applied to avocados with FRJS, the non-toxic pullulan coating can be easily washed down the sink and flushed down the drain. “You can package an avocado at the farm and extend its shelf life and then wash off the coating,” says study co-author Philip Democritou, a nanoaerosol researcher at Rutgers University and Harvard University. Even if the treated object itself is thrown away, the coating will decompose in the soil in about three days, the scientists said.
The team also tested how the coating improved food safety. When researchers compared it to common foodborne pathogens, including coli, Listeria innocent as well as Aspergillus fumigatus, they saw a decline in both bacterial and fungal populations. They also found that coated avocados were less prone to rotting, with only 50% of these fruits going bad within a week compared to 90% of uncoated avocados. And coated avocados were more likely to retain their green inner color.
Although this is not the first antimicrobial coating for food, the researchers believe that they have created the most effective and easily recyclable option to date. They claim that the spray technology requires less feedstock, making it more efficient than based on silk fiber coatings that require the food to be first immersed in the material and then dried. Other attempts at plastic-free food packaging have included cellulose-based films; they cannot be washed off, and some even need to be recycled.
According to Chang, the team is currently working on expanding the coating process to process multiple product items at the same time. The scientists are considering several options, including a pipeline-based system, but this is still in the early stages of planning.
The coating may also need to undergo additional safety testing, suggests Nishad Jayasundara, an environmental toxicologist at Duke University who was not involved in the study. “As a toxicologist,” he says, “the bottom line whenever you see a newly synthesized product is, ‘Do we know enough about it?’ break down into unexpected by-products.
Jayasundara says he is generally encouraged by the new study results. “It’s always very exciting when you have a biodegradable material that can replace plastic or reduce it at any level possible,” he says. But he doesn’t dare to celebrate yet. Although the U.S. Food and Drug Administration (FDA) has given pullulan the agency’s GRAS status, Jayasundara warns that whenever modifications are made to the material—even with natural additives, such as the antimicrobials the researchers used— it is important to assess their safety to human health through a series of tests.
“When we first thought about plastics, they were considered pretty safe molecules,” notes Jayasundara. “But over time we realized, ‘Oh, actually no, it’s not.’ We now know that plastic at all levels, regardless of size, has an impact at the cellular level, at the molecular level and at the ecosystem level.”