Water-insoluble tea polyphenol nanoparticles as fillers and bioactive agents for pectin films to prepare active packaging for fruit preservation

Polysaccharide films such as pectin are gaining attention as potential packaging materials that can replace petrochemical plastics. However, pectin has high brittleness and not biologically active, while current films used to address these issues often struggle to strike a balance between these properties. Herein, water-insoluble tea polyphenol nanoparticles (WI-TPN) were prepared by amino acid-induced Mannich condensation reaction to activate pectin films. WI-TPN has good compatibility and can be uniformly and stably dispersed in pectin film-forming solutions, thus facilitating hydrogen bonding interactions between them and the pectin matrix. WI-TPN can be used both as a nanofiller to enhance the mechanical properties of films and as a bioactive agent to impart unique bioactivity to the films. Compared to pure pectin films, pectin-WI-TPN composite films have higher tensile strength (22.36 MPa), hydrophobicity (78.28o), thermal stability. More importantly, WI-TPN gives pectin films unique UV-blocking properties (almost completely block the UVC (200–275 nm), UVB (275–320 nm) and UVA (320–400 nm) spectra), antioxidant (DPPH free radical scavenging capacity and T-AOC were maximized by 9.91 times and 10.58 times, respectively) and antibacterial activity (bacterial growth curve was slow), which allows it to significantly extend the shelf life of strawberries when used for packing them. In conclusion, this work provides a new idea for balancing the multiple properties of pectin-based films, and the preparation of stabilized high-performance films have great potential for application in food packaging, especially perishable food packaging.