A new study published in Food Quality and Safety (DOI: 10.1093/fqsafe/fyag032) demonstrates that underused rapeseed-processing residues can be converted into a biodegradable active packaging film that keeps food fresher for longer. The research, conducted by scientists from Dalian Polytechnic University and INNOBIO Corporation Limited, addresses two pressing challenges: the environmental persistence of petroleum-based plastics and the underutilization of agricultural byproducts.
Modern food packaging must shield products from moisture, oxygen, light, and microbial spoilage, but conventional plastics remain in landfills for centuries. Bio-based films offer a renewable alternative, yet pure chitosan (CS) films often lack the mechanical strength, water resistance, and active protection needed for demanding preservation. Rapeseed production generates large quantities of cakes, stems, leaves, and flowers that are rich in cellulose, polyphenols, and flavonoids—compounds with untapped potential for packaging applications.
The team extracted bioactive compounds from these residues and used them to biosynthesize silver nanoparticles (AgNPs) under mild conditions. These were then embedded into a chitosan matrix to form composite films. Compared with pure chitosan, the rapeseed-cake extract–silver nanoparticle film exhibited a tensile strength increase from 8.1 to 17.0 MPa, a rise in elongation at break from 20.7% to 31.5%, and a water contact angle jump from 55.7° to 87.2°, indicating improved water resistance. The flower-based film showed the strongest antioxidant activity, with 89.7% DPPH scavenging and 62.3% ABTS scavenging, while the rapeseed-cake film inhibited Escherichia coli and Staphylococcus aureus.
In storage tests, coated cherry tomatoes retained more weight, ascorbic acid, and titratable acidity, while packaged enoki mushrooms exhibited less browning and microbial deterioration. The films fully degraded in soil within 21 days without significantly affecting bok choy growth, supporting a more circular packaging system.
“The central message is that crop residues can do more than replace part of a packaging material: their natural chemistry can help the package actively protect food,” the authors stated. By pairing rapeseed phenolics with biosynthesized AgNPs, the team created a film that is stronger, less vulnerable to moisture, and better able to slow oxidation and microbial growth. The produce trials are especially important because they move the concept beyond laboratory measurements and demonstrate performance on highly perishable foods with different spoilage patterns.
The films could serve as coatings, wraps, or liners for fresh produce and other foods vulnerable to dehydration, oxidation, browning, and microbial spoilage. Their use could create new value streams for rapeseed-processing residues while reducing dependence on persistent plastics. However, commercial translation will require scalable manufacturing, cost and sensory assessments, standardized food-contact testing, and trials under realistic transport and storage conditions. While EDS found no detectable silver on tested tomatoes, the study describes this as preliminary evidence, and future work should employ quantitative methods such as ICP-MS to assess migration and evaluate degradation in diverse environments.
The research was funded by the Basic Scientific Research Fund of Liaoning Provincial Education Department and the China Postdoctoral Science Foundation. The full study is available at https://doi.org/10.1093/fqsafe/fyag032.
