Preparation and characterization of PH-responsive polyvinyl alcohol/chitosan/anthocyanin films

Abstract Anthocyanin/polyvinyl alcohol/chitosan composite membrane was prepared by solution casting method using chitosan (CS) and polyvinyl alcohol (PVA) as matrix and natural pigment anthocyanin as filler. The structures of the composite films were characterized by Uv-visible reflectance spectrum (UV-VIS), Fourier infrared spectroscopy (FT-IR) and the scanning electron microscopy (SEM). The effects of adding anthocyanins on the physical properties, water resistance, degradation, antibacterial properties and pH responsiveness of the films were investigated. The experimental results showed that the prepared anthocyanin/polyvinyl alcohol/chitosan composite indicator films show color changes from pink to purple to blue and then to yellow-green when the pH value ranges from 2 to 14. The total color difference ΔE value is greater than 12. The antibacterial properties and other properties of the composite film can enhance by adding anthocyanin. The tensile strength of anthocyanin/polyvinyl alcohol/chitosan film is more than 70 MPa, which is larger than that of polyvinyl film and polyvinyl alcohol/chitosanfilm. The film has excellent physical, antibacterial properties and obvious pH response performance, making it ideal for food packaging.