Researchers have developed a new type of biodegradable food packaging that turns underused rapeseed processing residues into an active film capable of preserving fresh food while reducing reliance on petroleum-based plastics. The material, described in a study published in the journal Food Quality and Safety, combines chitosan with phenolic extracts from rapeseed cake, flowers, stems, and leaves, plus biosynthesized silver nanoparticles. This combination enhances the film's strength, water resistance, and UV protection, and adds antioxidant and antimicrobial properties. In storage tests, the films slowed quality loss in cherry tomatoes and enoki mushrooms, and soil-burial experiments showed complete degradation within three weeks, supporting more circular packaging systems.
The research addresses a critical challenge in food packaging: conventional plastics protect food but persist in the environment for centuries. Bio-based films offer a renewable alternative, but many lack the mechanical strength, barrier performance, and active protection needed for demanding preservation conditions. Rapeseed production generates large amounts of cake, stems, leaves, and flowers that are rich in cellulose, polyphenols, and flavonoids, yet much of this biomass is underutilized. This study, conducted by scientists from Dalian Polytechnic University and INNOBIO Corporation Limited, demonstrates a way to convert these agricultural residues into high-value functional materials.
The team extracted bioactive compounds from rapeseed processing residues and used them to synthesize silver nanoparticles under mild conditions. These were then incorporated into a chitosan matrix to create composite films. Analysis revealed that the films had smooth, compact structures with well-dispersed silver nanoparticles. Compared to pure chitosan, the rapeseed-cake extract–silver nanoparticle film showed a tensile strength increase from about 8.1 to 17.0 MPa and a water contact angle rise from 55.7° to 87.2°, indicating improved water resistance. The flower-based film exhibited the strongest antioxidant activity, with 89.7% scavenging in the DPPH assay and 62.3% in the ABTS assay. The rapeseed-cake film effectively inhibited Escherichia coli and Staphylococcus aureus.
Practical trials on fresh produce showed that coated cherry tomatoes retained more weight, ascorbic acid, and titratable acidity, while packaged enoki mushrooms had less browning and microbial deterioration. The films also fully degraded in soil within 21 days without significantly affecting bok choy growth, indicating their potential for compostable packaging.
The implications of this research are significant for the food packaging industry and sustainability efforts. The films could be used as coatings, wraps, or liners for fresh produce and other foods vulnerable to dehydration, oxidation, and microbial spoilage. By turning rapeseed residues into valuable packaging materials, this approach creates new revenue streams for farmers and reduces dependence on persistent plastics. However, the authors note that commercial translation will require scalable manufacturing, cost and sensory assessments, standardized food-contact testing, and trials under realistic transport and storage conditions. While energy-dispersive X-ray spectroscopy found no detectable silver on tested tomatoes, the study describes this as preliminary evidence, and future work should use quantitative methods like ICP-MS to assess long-term exposure and degradation in diverse environments.
The study was funded by the Basic Scientific Research Fund of Liaoning Provincial Education Department and the China Postdoctoral Science Foundation. The findings highlight the potential of using agricultural waste to create active packaging that not only protects food but also addresses environmental concerns, offering a path toward more sustainable food systems.
