Eco‐friendly biodegradable film based on kombucha mushroom/corn starch/parsley extract: Physicochemical and antioxidant/antibacterial properties

The main purpose of this study was to produce biodegradable film based on kombucha mushroom (KM), so kombucha mushroom was grown and used to prepare biodegradable film. Glycerol (Gl), corn starch (St), and parsley extract (PE) were used to improve the characteristics of the kombucha mushroom-based film. The physicochemical, thermal, and antibacterial properties of the films were investigated using different techniques. The obtained results showed that starch significantly increased the tensile strength of the film (3 Mpa) and glycerol improved the flexibility of the film (70%). Starch increased the film's resistance to dissolution in water, and parsley extract and starch improved water vapor permeability. The pure film of kombucha mushroom had good antioxidant (40% ± 2%) and antibacterial properties, and parsley extract significantly increased these properties of the film, so that the prepared film can be considered as an active film. Starch had no significant effect on antioxidant and antibacterial properties. The pure kombucha mushroom film had cracks on the surface, and the addition of starch removed these cracks and made the structure of the film more homogeneous. Electrostatic interactions between kombucha mushroom, glycerol, starch, and parsley extract were confirmed by Fourier transform infrared spectroscopy (FTIR) results. The pure film of kombucha mushroom was a completely amorphous film, which glycerol, parsley extract, and starch improved the crystallinity of the film. Glycerol and parsley extract decreased the thermal resistance of the film, but starch increased this property significantly (about 40°C), so that the kombucha mushroom/glycerol/starch/parsley extract composite film had the highest thermal resistance. In addition to having acceptable mechanical, thermal, and structural properties, the film based on kombucha mushroom can be used as an active film in the packaging of food products sensitive to microbial and oxidative spoilage due to having suitable antioxidant and antimicrobial properties.