Innovation & Technology Circular Economy

A Cracking New Use for Shellfish Waste:
Extending the Life of Produce

University of Maryland researchers have developed a new type of porous material made of chitosan and copper to spray on fresh produce that absorbs chemical pesticides, extends shelf life and easily washes off.

Published 4 months ago | About a 3 minute read

Image: John T Consoli

Crab shells have emerged as something of a dark horse in recent years, in terms of their utility in improving sustainability: The typically wasted shells of crabs and their fellow crustaceans are composed of a biopolymer that is proving increasingly useful in everything from wastewater treatment and solar cells to biodegradable alternatives to plastic and polystyrene packaging.

Now, University of Maryland (UMD) researchers have engineered a material made from the biopolymer — chitosan — that not only extends the shelf life of produce; it also removes chemical pesticides and herbicides.

The new technology, made of a derivative of crab and shrimp shells, is designed to form a microscopically thin nanocrystal layer on the treated produce — absorbing and removing chemical residues. The work, published in the journal Matter, was a collaboration among researchers in the University’s Departments of Materials Science and Engineering and Nutrition Food and Science.

"This work offers a viable solution to improve food safety associated with our daily life," said Qin Wang, a professor in nutrition and food science and collaborator in the study.

While the idea of coatings made from organic material to slow produce spoilage isn’t new — solutions from companies including Apeel, Foodberry, Lidl and Mori are hard at work on that front — none of them have the added benefits of also removing chemical pesticides; pesticide residues on fruits and vegetables have been linked to severe health problems — including increased risks of cancer, attention-deficit hyperactivity disorder and Alzheimer's disease.

Common household cleaners, ranging from vinegar, baking soda or salt solutions to more costly alternatives such as hydrogen peroxide and ozone, are widely used to remove pesticides and herbicides; but they are either not entirely effective or can damage or alter the produce's appearance and taste. The washing process itself may also shorten the shelf life due to "micro-wounds" such as bruises formed on the fruit’s surface.

The UMD solution is a new type of porous material made of chitosan and copper, which has antimicrobial properties — the researchers tested it by spraying a thin layer on strawberries, whose highly porous structure makes them efficient absorbers of chemical residues.

The researchers also developed a smartphone app that consumers could use at home to check the chemical residue level, which found this new material was effective in absorbing them; the coating also enhanced the fruit's shelf life and was easily rinsed off. The team says the simplicity of the washing process, combined with an easy method for evaluation of residue levels via smartphone-based image analysis, offers a practical and consumer-friendly approach to enhancing food safety and quality.

Consisting only of materials and chemicals that are Generally Recognized as Safe (GRAS), a designation established by the US Food and Drug Administration, the technology is also highly scalable.

This isn’t UMD’s first foray into working with crab shells or developing innovative food-waste solutions:

Earlier this year, a multidisciplinary team led by UMD’s College of Agriculture and Natural Resources was awarded $5 million from the National Science Foundation to develop NourishNet: a comprehensive, technology-based approach to tackling food waste and insecurity featuring “Quantum Nose” — a portable, user-friendly food-quality sensor that can detect early-stage food spoilage; and FoodLoops — a real-time app to be developed to optimize surplus food distribution to food-insecure people.
In 2022, the school’s Department of Materials Science and Engineering developed a zinc battery — which could be used to store energy for electric vehicles and wind and solar installations — with a biodegradable, chitosan-based electrolyte that could help solve the issue of unrecyclable waste from conventional end-of-life batteries. The biodegradable electrolyte in the zinc and chitosan battery means that about two-thirds of it could be broken down by microbes, leaving behind the metal component — in this case, zinc — rather than lead or lithium.