A research team has developed a biodegradable active film from rapeseed-processing residues that could reduce reliance on petroleum-based packaging while extending the shelf life of fresh produce. The material, described in a study published in Food Quality and Safety (DOI: 10.1093/fqsafe/fyag032), combines chitosan with phenolic extracts from rapeseed cake, flowers, stems, and leaves, along with biosynthesized silver nanoparticles. This formulation strengthens the film, improves water and oxygen resistance, and adds antioxidant and antimicrobial properties, according to the researchers from Dalian Polytechnic University and INNOBIO Corporation Limited.
The study addresses the limitations of conventional bio-based films, which often lack the mechanical strength and barrier performance needed for demanding food preservation. Rapeseed production generates substantial byproducts rich in cellulose, polyphenols, and flavonoids that are typically underutilized. By extracting these bioactive compounds and using them to synthesize silver nanoparticles, the team created a composite film with enhanced properties. Compared with pure chitosan, the film made with rapeseed cake extract and silver nanoparticles exhibited a tensile strength increase from 8.1 to 17.0 MPa and an elongation at break rise from 20.7% to 31.5%. Its water contact angle increased from 55.7° to 87.2°, indicating improved water resistance. The flower-based film demonstrated the highest antioxidant activity, with 89.7% DPPH and 62.3% ABTS scavenging, while the cake-based film inhibited Escherichia coli and Staphylococcus aureus.
In storage tests, the films slowed quality deterioration in cherry tomatoes and enoki mushrooms. Coated tomatoes retained more weight, ascorbic acid, and titratable acidity, while packaged mushrooms showed reduced browning and microbial growth. The films fully degraded in soil within 21 days without significantly affecting bok choy growth, supporting their potential for circular packaging systems.
The authors emphasize that this approach turns agricultural waste into a functional resource, moving beyond simple material replacement. The films could be used as coatings, wraps, or liners for fresh produce and other perishable foods. However, commercial application requires scalable manufacturing, sensory assessments, standardized food-contact testing, and trials under real-world conditions. While energy-dispersive X-ray spectroscopy found no detectable silver on tested tomatoes, the study notes this is preliminary, and quantitative methods like ICP-MS are needed for definitive migration analysis.
The research was funded by the Basic Scientific Research Fund of Liaoning Provincial Education Department and the China Postdoctoral Science Foundation. Food Quality and Safety is an open-access journal with a 2025 impact factor of 4.9.
