Plasma Surface Modified Polystyrene and Grafted with Chitosan Coating for Improving the Shelf Lifetime of Postharvest Grapes

Abstract

The antimicrobial coating on plasma treated packaging polymer materials are potential and alternative techniques for extending the post harvest life of fresh fruits and vegetables. The present work is to evaluate the shelf life time of post harvest grapes stored in different plasma (air, argon and oxygen) treated and chitosan coated polystyrene (PS) petri plates at atmospheric condition (room temperature 28 °C). The plasma treatments were used to activate the inert PS film surface to enhance the adhesion of chitosan coating. Plasma treatments on the PS film changed the chemical and morphological properties were investigated by ATR-FTIR, EDS and FE-SEM analyses. The contact angle measurement conforms that the air, argon and oxygen plasma treatments greatly enhanced the hydrophilicity of PS and the greater decrease was found in oxygen plasma treatment. Further, the chitosan was immobilised onto PS surface utilizing dip coating and it was characterized by contact angle, ATR-FTIR and FE-SEM evaluations. XPS result indicates the chitosan was efficiently immobilized on the PS film. Subsequently the shelf life time and weight loss (%) was calculated for table grapes stored in the air, argon and oxygen plasma treated with chitosan coated PS. The result suggests that oxygen plasma treatment along with chitosan coating on PS demonstrates the active packaging to extend the self-life time of grapes than the other PS.