2026-06-30
Researchers in China have reported a new biodegradable film for grape preservation that combines chitosan and potato starch with calcium ascorbate and gold-core, silver-shell nanoparticles, a mix they say improved strength, water resistance and antimicrobial performance compared with standard versions of the material.
The study was published Tuesday in npj Science of Food by scientists from the Chinese Academy of Agricultural Sciences, Beijing Technology and Business University, Southwest University and other affiliated research centers. The team said the work addresses a common problem in food packaging research: many chitosan-based films show promise in the lab but fall short in stability, antibacterial action and long-term preservation.
The film was made through what the authors described as a one-pot process. In the design, calcium ascorbate serves two roles. It acts as an ionic crosslinker that helps hold the material together, and it also contributes antioxidant and antimicrobial activity. The embedded Au@Ag nanoparticles were added to further strengthen the film’s functional properties.
According to the paper, the modified film showed higher tensile strength than the base chitosan-potato starch film, rising from 7.58 MPa to 8.76 MPa. Its water vapor transmission rate fell from 0.312 to 0.271 g·m−2·h−1, indicating better resistance to moisture transfer. The researchers also reported high water stability and about 99% blocking of ultraviolet light.
The team tested antioxidant activity using ABTS and DPPH radical-scavenging assays and said the composite film performed better than the control chitosan-starch film. In antibacterial tests, the material achieved 100% inhibition against Escherichia coli and Staphylococcus aureus, two bacteria commonly used to evaluate food safety materials.
The practical test focused on grapes, a fruit that is highly perishable after harvest and vulnerable to moisture loss, microbial growth and skin damage during storage and transport. The researchers said the new film adhered well to the grape surface because of its lower water contact angle, which increased direct contact and improved antimicrobial action. In those preservation trials, grapes wrapped with the new composite film lasted longer than grapes covered with commercial polyethylene wrap.
The paper presents the material as a possible alternative to petroleum-based plastic packaging. The authors also said it showed good biosafety and could degrade in soil, two points that matter as food producers and retailers face pressure to reduce plastic waste without shortening shelf life.
The findings may also matter beyond fresh produce markets. Grapes are a key raw material for wine, juice and other beverages, and losses after harvest can affect both supply and quality before fruit reaches processing facilities. If films like this can be scaled at reasonable cost and meet regulatory standards, they could help reduce spoilage and improve consistency in fruit delivered to wineries or other beverage producers.
The study does not settle whether the material is ready for commercial use. The article reports laboratory characterization and preservation tests, but large-scale manufacturing, cost, regulatory review and market acceptance remain open questions. The inclusion of gold-core, silver-shell nanoparticles could also draw close scrutiny from regulators and buyers because nanomaterials in food-contact packaging often face additional safety evaluation.
Still, the work adds to a growing area of research aimed at replacing conventional plastic wraps with biodegradable films that do more than act as passive barriers. By combining structural reinforcement with antioxidant, antimicrobial and UV-blocking functions in one material, the researchers are trying to extend shelf life while limiting environmental impact.
The paper was received on Feb. 3, accepted on June 23 and published on June 30. The authors reported no competing interests. Funding came from several Chinese public research programs, including the Chinese Academy of Agricultural Sciences, the Beijing Natural Science Foundation and China’s National Key Research and Development Program.