Nano-TiO2 particles and high hydrostatic pressure treatment for improving functionality of polyvinyl alcohol and chitosan composite films and nano-TiO2 migration from film matrix in food simulants

This study investigated the impact of nano-TiO 2 and high hydrostatic pressure (HHP) treatment on microstructure, water vapor and gas barrier, antibacterial and mechanical properties of polyvinyl alcohol (PVA)–chitosan (CHI) biodegradable films and determined the migration behavior of TiO 2 nanoparticles from the films to food simulants. Apart from the effect of filler, TiO 2 nanoparticles also could improve the antibacterial activity of the films and play a role as a plasticizer in the films. HHP treatment promoted the interaction between PVA and chitosan molecules, resulting in the formation of more compacted network structures in PVA–CHI films. The migration of TiO 2 from the films was investigated in food simulants including distilled water, acetic acid, ethanol and olive oil, in which the trace amount of TiO 2 (<   4.20   ×   10 −   3 ‰) was only detected in olive oil. HHP treatment at 200–400   MPa significantly reduced migration of TiO 2 nanoparticles from the films. Industrial relevance Results from this study provide a new application direction of high hydrostatic pressure (HHP) in the field of food packaging materials for improving the functionality of materials. Due to the non-thermal characteristic, HHP in combination with nano-TiO 2 not only improved the mechanical and barrier properties of the biodegradable PVA–CHI composite films (polyvinyl alcohol and chitosan based materials), but also enhanced the antibacterial activity of the films. The HHP treated PVA–CHI–TiO 2 films are very stable in food simulants, such as olive oils. Therefore, the utilization of HHP and nano-TiO 2 is promising in the preparation of food packaging materials with desirable functionalities.