Improving functional properties of zein film via compositing with chitosan and cold plasma treatment

In order to improve their functional properties, zein films were modified by a two-step method consisting of compositing with chitosan, followed by exposure to cold plasma. Various aspects were assessed to evaluate the influence of modification on the properties of the films. After the two-step modification, the water contact angle of the zein films significantly dropped from 75.18 degrees to 29.19 degrees. Moreover, the films showed a notable increase in their elongation at break, from 1.13% to 4.13%, mainly attributed to the presence of chitosan. Additionally, upon a 60 s plasma treatment, the composite film exhibited an optimum tensile strength, an enhanced water vapor barrier as well as improved thermal stability. Evaluation with ATR-FTIR revealed the secondary structure of zein molecules became ordered and found the more hydrogen bonds formed between zein and chitosan with plasma treatment. This study showed the benefits of our two-step modification to potentially improve zein-based film performance in packaging industries.