As food costs continue to rise and a global food crisis looms on the horizon, it’s staggering to think that some 30-40% of America’s food supply ends up in landfills, mostly due to spoilage. At the same time, the World Health Organization estimates that foodborne illness from microbial contamination causes about 420,000 deaths per year worldwide.
What if there were a way to package fresh foods that could extend their shelf life and eliminate microbial contamination?
Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Harvard T.H. Chan School of Public Health have developed a biodegradable, antimicrobial food packaging system that does both.
“One of the biggest challenges in the food supply is the distribution and viability of the food items themselves,” said Kit Parker, the Tarr Family Professor of Bioengineering and Applied Physics at SEAS and senior author of the paper. “We are harnessing advances in materials science and materials processing to increase both the longevity and freshness of the food items and doing so in a sustainable model.”
From the battlefield to the farm
The new food packing system has its roots in battlefield medicine. For more than a decade, Parker and his Disease Biophysics Group have been developing antimicrobial fibers for wound dressings. Their fiber manufacturing platform, known as Rotary Jet-Spinning (RJS), was designed specifically for that purpose.
RJS works likes a cotton candy machine — a liquid polymer solution is loaded into a reservoir and pushed out through a tiny opening by centrifugal force as the device spins. As the solution leaves the reservoir, the solvent evaporates, and the polymers solidify to form fibers, with controlled diameters ranging from microscale to nanoscale.
The idea to translate the research from wound dressing to food packing was born of a collaboration with Philip Demokritou, the former co-Director of the Center for Nanotechnology and Nanotoxicology (NanoCenter) at Harvard’s Chan School.
Making food more sustainable
To make the fibers food-safe, the team turned to a polymer known as pullulan. Pullulan is an edible, tasteless and naturally occurring polysaccharide commonly used in breath fresheners and mints.
The researchers dissolved the pullulan polymer in water and mixed it with range of naturally derived antimicrobial agents, including thyme oil, nisin and citric acid. The solution is then spun in an RJS system and the fibers are deposited directly on a food item. The researchers demonstrated the technique by wrapping an avocado with pullulan fibers. The result resembles a fruit wrapped in spiderweb.
The team demonstrated that their fiber wrapping increased the shelf life of avocado, a notoriously finicky fruit that can turn from ripe to rotten in a matter of hours. After 7 days on a lab bench, 90% of unwrapped avocados were rotten while only 50% of avocados wrapped in antimicrobial pullulan fibers rotted.
The wrapping is also water soluble and biodegradable, rinsing off without any residue on the avocado surface.
The lab’s latest innovations in food packaging may also soon enter commercial development. Harvard Office of Technology Development has protected the intellectual property relating to this project and is now exploring commercialization opportunities with Parker’s lab.
