A research team has developed a biodegradable active film from underused rapeseed-processing residues, offering a sustainable alternative to petroleum-based packaging while extending the shelf life of fresh produce. The material, described in the journal Food Quality and Safety, combines chitosan with phenolic extracts from rapeseed cake, flowers, stems, and leaves, along with biosynthesized silver nanoparticles (AgNPs). This composite enhances the film's mechanical strength, water resistance, and barrier properties, while adding antioxidant and antimicrobial activities that actively protect food.
The study addresses the limitations of conventional bio-based films, which often lack the durability and active protection required for demanding preservation conditions. By utilizing rapeseed byproducts rich in cellulose, polyphenols, and flavonoids, the researchers created a multifunctional packaging system that not only performs well but also valorizes agricultural waste. The films showed significant improvements over pure chitosan: tensile strength increased from 8.1 to 17.0 MPa, elongation at break rose from 20.7% to 31.5%, and the water contact angle increased from 55.7° to 87.2°, indicating reduced water affinity. The flower-based film exhibited the highest antioxidant activity, with 89.7% DPPH and 62.3% ABTS scavenging, while the rapeseed-cake film inhibited Escherichia coli and Staphylococcus aureus.
Storage tests on cherry tomatoes and enoki mushrooms demonstrated the films' practical benefits: coated tomatoes retained higher weight, ascorbic acid, and titratable acidity, while packaged mushrooms showed reduced browning and microbial deterioration. Soil-burial experiments confirmed complete degradation within 21 days, with no adverse effects on bok choy growth, supporting a circular packaging approach. The authors emphasize that crop residues can do more than replace part of a packaging material; their natural chemistry can actively help preserve food.
These films could be applied as coatings, wraps, or liners for fresh produce and other perishable foods, reducing reliance on persistent plastics while creating new value streams for rapeseed-processing residues. However, commercial translation requires scalable manufacturing, cost and sensory assessments, standardized food-contact testing, and trials under real-world conditions. The study notes that while EDS found no detectable silver on tested tomatoes, this is preliminary; future work should employ quantitative methods like ICP-MS to assess migration and evaluate degradation in diverse environments.
The research, funded by the Basic Scientific Research Fund of Liaoning Provincial Education Department and the General Project of China Postdoctoral Science Foundation, highlights the potential of integrating agricultural waste into advanced packaging solutions, addressing both food waste and plastic pollution.
