Active Biodegradable Polyvinyl Alcohol–Hemicellulose/Tea Polyphenol Films with Excellent Moisture Resistance Prepared via Ultrasound Assistance for Food Packaging

Poor water-vapor barriers and mechanical properties are common problems of biobased films. To maintain food quality, the barrier and its strength performance need to be improved. Tea polyphenols (TP) are a natural active substance, and their benzene ring structure provides a barrier for them as a film material. Films that incorporate TP also have enriched functionalities, e.g., as antioxidants. Here, active poly (vinyl alcohol) (PVA)-hemicellulose (HC)/TP films with good moisture resistance and antioxidant capacity were prepared via ultrasound assistance. The effects of TP incorporation and ultrasonication on the physical, antioxidant, and micromorphological properties of the films were investigated. Results showed that the addition of TP improved the thermal stability and water-vapor permeability (WVP) of the composite films. When a PVA-HC/TP composite film with a PVA-HC to TP mass ratio of 100:10 was treated with ultrasonication for 45 min, tensile strength was 25.61 Mpa, which was increased by 54% from the film without any treatment, and water-vapor permeability (WVP) value declined from 49% to 4.29 × 10−12 g·cm/cm2·s·Pa. More importantly, the films’ DPPH scavenging activity increased to the maximal levels of 85.45%. In short, these observations create a feasible strategy for preparing high-performance biodegradable active-packaging films.