Nanofiber packaging film can extend kiwifruit shelf life, study finds

Scientists have developed a multifunctional nanofibrous film capable of preserving kiwifruit with antibacterial activity and photocatalytic ethylene degradation. 

The study, published in Food Quality and Safety, created multifunctional film via electrospinning. It used polyvinyl alcohol (PVA) and pullulan (PUL) as a composite polymer matrix, and incorporated with titanium dioxide (TiO2) nanoparticles and thymol (THY) as photocatalyst and natural antimicrobial agent, respectively.

According to the scientists at the Functional Packaging and Food Quality Control Team from Shanghai Jiao Tong University, China, the TiO2/THY/PUL/PVA nanofibrous film can effectively extend the shelf life of kiwifruit to more than 35 days and postpone the decline of fruit firmness, allowing the fruits to maintain total soluble solids, vitamin C, and anthocyanins.

Jin Yue, professor from the Department of Food Science and Engineering at Shanghai Jiao Tong University, and corresponding author of the study, tells Packaging Insights: “Kiwifruit faces two major postharvest challenges, including rapid ripening and softening driven by ethylene, and deterioration caused by microbial infection. Our film was designed to address the two processes within a single packaging material.”

“The film incorporates TiO2 nanoparticles and thymol into electrospun pullulan/PVA nanofibers. Under light irradiation, TiO2 acts as a photocatalyst and generates reactive oxygen species (ROS) that oxidize ethylene into CO2 and water, thereby reducing ethylene accumulation and delaying fruit ripening. At the same time, thymol, as a natural antimicrobial compound, is slowly released from the nanofibers and inhibits spoilage microorganisms. In addition, TiO2-generated ROS produces a synergistic antimicrobial effect with thymol.”

Yue tells us that by simultaneously regulating physiological senescence and microbial spoilage, the film enables the maintenance of firmness, nutritional quality, and overall appearance of fruits during storage. “Therefore, this dual function is particularly important for kiwifruit preservation,” she says.

Advancing food preservation

Yue shares that the current study demonstrates the feasibility and preservation potential of this multifunctional packaging film for climacteric fruit.

“Before commercial application, several important steps would still be required. Firstly, the film would need to be produced at a larger scale using a continuous and cost-effective manufacturing process while maintaining uniform nanofiber structure and consistent functional performance.”

“Secondly, its performance should be validated under realistic commercial conditions, including different kiwifruit varieties, package formats, cold-chain environments, transportation conditions, and larger storage volumes.”

“Thirdly, food-contact safety and regulatory compliance would also need to be systematically evaluated, particularly with respect to the migration and long-term stability of TiO2 and thymol,” she concludes.

Industry stakeholders are advancing packaging materials and technologies to help reduce food waste.

Last month, researchers at Kyushu University, Japan, used pumpkin peel as a raw material to synthesize a nanomaterial for food packaging that slows the deterioration of fruit and other produce while reducing transport damage.

This year, StePacPCC introduced a packaging solution for preserving the freshness of pitaya, commonly known as dragon fruit, during their journey from Ecuador to the US and Europe.

Earlier, South Korean researchers developed biodegradable chitosan and gallic acid conjugate fruit packaging that could reduce food waste while improving sustainability and freshness.