Biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) films coated with tannic acid as an active food packaging material

Non-biodegradable plastic packaging waste, such as polyethylene and polypropylene, is increasing, resulting in environmental pollution. In this study, we prepared ecofriendly food packaging films using poly(3-hydrox-ybutyrate-co-4-hydroxybutyrate) (P3HB-4HB), a microbially produced biodegradable aliphatic polyester, as a replacement for non-degradable packaging films. The films were prepared using hot-pressing and surface -modified to be hydrophilic via N2 plasma treatment. Finally, the films were coated with tannic acid (TA) by dip-coating. The effects of these treatments were investigated, and the antioxidant and antibacterial properties of the P3HB-4HB film were evaluated. We found that the TA coating improved the film's mechanical and thermal properties, which had been reduced by the N2 plasma treatment. Importantly for packaging applications, the TA coating did not affect the visible-light transparency. The films were used to store bananas, and lower weight loss and browning were observed compared to those of non-packaged bananas, demonstrating the promise of the prepared films.