Multilayer zein/gelatin films with tunable water barrier property and prolonged antioxidant activity

Multilayer edible films were fabricated with the stacking order of hydrophobic zein outer layer, hybrid zein/gelatin middle layer and the hydrophilic gelatin inner layer (Z-ZG-G). Cross-section morphology of films varied as the middle layer composition changed and tunable one-way water barrier property can be gained by regulating the ratio of zein/gelatin in middle layer. Tea polyphenol (TP) with concentration gradient was then loaded into the middle and inner layer of the optimized multilayer film to achieve prolonged release property. TP released from the multilayer film in a prolonged manner and the release kinetic was closely related to the structure responses of each film layer. When applied on freshly cut fruits, the TP loaded multilayer film exhibited preservation effects in terms of controlling weight loss, preventing rapid browning and inhibiting bacterial deterioration. The presented work offers an effective way in fabricating multilayer films with rationally designed functionalities, which could be practically useful in the fresh fruit and vegetable packaging industry.