From Pumpkin Peel to Packaging?

The following article was first published on the “Food Science” News page of Food and Wine magazine and is being shared here for AOTC readers interested in research related to pulp, paper, tissue, or packaging.

Concerns about microplastics in food packaging have fueled interest in more sustainable alternatives. In a recent study, a team of researchers from Kyushu University in Japan says they’ve developed an experimental alternative, and it’s made in part from food waste.

The team published its findings in the August issue of the journal Food Research International, detailing how they developed a new food packaging material from pumpkin peel. Compared with conventional plastic wrap, the pumpkin-derived material blocked more UV light, reduced microbial growth, and better preserved antioxidant activity, though it was less effective at preventing moisture loss.

“Our lab has long focused on extending the shelf life of agricultural produce while reducing reliance on petroleum-based plastics,” said Fumihiko Tanaka, a food scientist and one of the study’s authors.

How scientists turned pumpkin peel into food packaging 

To create the material, the researchers heated discarded pumpkin peel under high pressure, then freeze-dried it into carbon quantum dots: microscopic particles of black powder that have already shown promise in other food packaging research, where they were derived from eggplant peels. Acting as tiny protective particles, they can absorb UV light that accelerates food spoilage, inhibit the growth of some bacteria, and help neutralize reactive molecules that contribute to oxidation. The researchers combined the particles with plant fibers and gelatin to create a biodegradable composite film, not unlike Saran wrap, which was tested on cherry tomatoes against conventional plastic wrap and no packaging.

After 20 days, the pumpkin peel film outperformed no packaging and surpassed conventional plastic wrap in blocking UV light, reducing microbial growth, and preserving antioxidant activity. Conventional plastic remained more effective at limiting moisture loss.

“We understand safety is a key concern,” added food scientist M.A. Reshaka Kavindi, an author on the study. “Cell viability tests confirmed the material is non-toxic below 2 mg/mL, and the coating itself uses only a fraction of that amount, at roughly 0.01 millimeters thick. Consumers can further reduce exposure simply by washing or peeling.”

The pumpkin peel material also compared favorably with other antimicrobial food packaging technologies. “Conventional antimicrobial packaging typically relies on metal nanoparticles like zinc oxide or silver, which carry a larger environmental footprint than CQDs,” Fumina Tanaka, another study coauthor and associate professor at Kyushu University, explained. “Ours are derived from organic matter and show good biocompatibility at effective concentrations, something critical for any food contact material.”

Could this experimental packaging replace plastic? 

This study examined only the effectiveness of protective films, even though carbon dots have been incorporated into a variety of packaging materials in laboratory settings. The film developed by the Kyushu University team is still far from commercial use. So far, the researchers have tested it only on cherry tomatoes over a 20-day period, and they say additional research is needed to evaluate its performance on other foods and against a broader range of spoilage organisms, including molds.

The team is also exploring potential uses beyond food preservation. Because the carbon quantum dots fluoresce under UV light, the material could someday have applications in food packaging labels or other printed designs. “Under UV light, the carbon dots fluoresce, and the color shifts with particle size,” said Fumina Tanaka. “If we could eventually find a way to render text or illustrations with it, that would be pretty exciting too.”

About the Author: Stacey Leasca is an award-winning journalist with nearly two decades of newsroom experience. She is also the co-founder of Be a Travel Writer, an online course for the next generation of travel journalists.