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

Abstract

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/m2.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.