Development of multifunctional food packaging films based on chitosan, TiO2 nanoparticles and anthocyanin-rich black plum peel extract

Multifunctional food packaging films were developed based on chitosan (CS), nanosized TiO2 and black plum peel extract (BPPE). Effects of TiO2 and/or BPPE on the physical and functional properties of CS film were investigated. Results showed BPPE contained nine phenolic compounds with 23.29% of anthocyanins. The physical property of CS film could be significantly altered by incorporating TiO2 and/or BPPE. Notably, CSTiO2, CS-BPPE and CSTiO2-BPPE films all possessed higher barrier properties against water vapor and UV–vis light, and better mechanical strength than CS film. Scanning electron microscopy showed CS-BPPE film had a denser and smoother cross-section as compared to CS film. In addition, several white particles were clearly observed in the cross-section of CS-TO2 and CSTiO2-BPPE films. Fourier transform infrared spectroscopy and X-ray diffraction further revealed that CS could interact with TiO2 and BPPE through non-covalent bonds. Antioxidant assay showed CS-BPPE and CSTiO2-BPPE films both possessed strong free radical scavenging activity. Notably, CSTiO2-BPPE film exhibited the highest ethylene scavenging ability and antimicrobial activity among all films tested. Due to abundant anthocyanins in BPPE, the colors of CS-BPPE and CSTiO2-BPPE films were pH-sensitive. Our results suggest CSTiO2-BPPE film can be used as antioxidant, ethylene scavenging, antimicrobial and pH-sensitive food packing material.