Multifunctional bionanocomposite films based on konjac glucomannan/chitosan with nano-ZnO and mulberry anthocyanin extract for active food packaging

In this study, a series of multifunctional bionanocomposite films (KCZ-MAE) based on konjac glucomannan (KGM)/chitosan (CS) (KC) with Nano-ZnO and mulberry anthocyanin extract (MAE) were prepared by a solution casting method. Effects of Nano-ZnO and/or MAE on rheology of film-forming solutions (FFS), physicochemical properties and functional properties of the KC biocomposite films were systematically characterized. Cross-section microstructure of the films showed that the films were dense and compact. Although the incorporation of MAE decreased the transmittance of the films, it enhanced the UV-Vis light barrier properties. Water vapor permeability (WVP) of the films was decreased from 4.09 (g mm/m(2).day.kPa) for KC film to 2.84, 2.61, 1.82 and 2.40 for KCZ, KCZ-MAE I, KCZ-MAE II and KCZ-MAE III films, respectively. In contrast, the tensile strength (TS) of films increased from 42.83 MPa to 52.00 MPa. Also, KCZ-MAE films showed strong antioxidant activity, good thermal stability and good antibacterial activity against E. coli and S. aureus. KCZ-MAE films showed the higher antioxidant activity than KC and KCZ film, respectively 65.93%, 69.14% and 71.98%. Moreover, the KCZ-MAE films presented relatively wide color differences from red to blue in different buffer solutions (pH 2-12), which was clearly observed by the naked eye. The multifunctional bionanocomposite films have promising potential for applications in active and intelligent food packaging in the future.