USING ELECTROSTATIC DISCHARGE FOR COATING SURFACE OF POLYETHYLENE FILM WITH CHITOSAN SUBSTANCE TO EXTEND THE CUCUMBER SHELF LIFE

Abstract

This work focuses on, surface modification of polyethylene films by electrostatic discharge device and coating of chitosan on the surface of treated film. For this purpose, the surface of polyethylene film was treated by corona electrostatic discharge using different electrode gaps (0.5, 1 and 1.5 cm) and three levels of high voltage (5, 10 and 15 kV). Blown films of low density polyethylene having a thickness of 100 μm and a density of 0.92 g/cm3. The cucumbers (Cucumis sativus) of Cucumbitaceae family was used. The modified polymeric film was immersed in a solution of chitosan 3 wt% for 3 hrs. Physical characterization and antimicrobial activity of chitosan/polyethylene film were evaluated and then it was used as an active package to extend shelf life of cucumber during storage at 4°C. The antimicrobial activity of chitosan/polyethylene composite was evaluated and then it was used as an active package to extend shelf life of cucumber during storage at 4°C. The surface modification of polyethylene films by electrostatic discharge machine (10 kV and 1 cm gap) and coating of chitosan substance was the best in the physical properties of other treatments. The obtained results showed that, chitosan/polyethylene composite film has high antimicrobial properties against Listeria monocytogenes, Pseudomonase aeroginosa and Fusarium oxysporum. Finally, the cucumber storage indicated that, cucumber rapped in chitosan/polyethylene composite have value of weight loss, pH and total aerobic bacteria count as well as yeast and mold count lower than other samples(unwrapped and wrapped in native polyethylene).