Conducting/smart color film based on wheat gluten/chlorophyll/polypyrrole nanocomposite

In this research biodegradable films based on wheat gluten modified with chlorophyll/polypyrrole (WG/Ch/PPy) were prepared. Some characteristics of synthesized films including; thickness, solubility, water vapor permeability (WVP), moisture, opacity, color, antioxidant, and antimicrobial and conductivity properties were studied. According to the results, by adding chlorophyll and polypyrrole to gluten film, the solubility was significantly decreased. The opacity of films was significantly increased with adding chlorophyll and polypyrrole, where the effect of polypyrrole was higher than chlorophyll. With the addition of chlorophyll and polypyrrole, the antioxidant activity of the films was increased. According to the mechanical properties, the addition of chlorophyll and polypyrrole increased the tensile strength of the films. Also results showed that chlorophyll had no effect on the antibacterial property against Escherichia coli, but PPy enhanced the antibacterial character of gluten film significantly. FT-IR results confirmed the creation of new interaction between gluten, PPy and chlorophyll. SEM results showed that PPy particles (40-100 nm) uniformly covered the film surface. XRD results showed that PPy and chlorophyll decreased the crystalline structure of gluten film. The WG/Ch/PPy film can be used as smart film because of its conductivity change and color change. The changing of film conductivity and film color during storage time of food can represent food quality.