Development of packaging film from LDPE/zeolite composites for extending shelf life of fresh produces

Abstract

In this study, LDPE/zeolite composite films were prepared via twin screw extruder attached with blown film set. LDPE and maleic anhydride grafted low density polyethylene (PE-g-MA) was melt blended with zeolite. The effect of PE-g-MA to zeolite ratio, type and content of zeolite on the dispersion of zeolite in composite films was determined. In addition, thermal, mechanical, and gas permeability properties of these composite films were also studied. The chosen composite film was investigated the efficiency on prolonging shelf life and maintaining quality of lime and mango fruits. From SEM results, LDPE/zeolite composite films with PE-g-MA/zeolite ratios of 3.0 and 4.0 showed better dispersion and distribution than those with other ratios. The addition of PE-g-MA into LDPE matrix decreased melting temperature (Tm) and the formation of crystalline phase of LDPE which was confirmed by DSC results. However, the addition of zeolite into LDPE matrix did not affect the formation of crystalline phase. In addition, it was found that LDPE/zeolite composite film at zeolite 5A of 3 phr and PE-g-MA/zeolite ratio of 3.0 exhibited the optimal mechanical and gas permeability properties. The composite film used as packaging prolonged shelf life of mango fruit for 4 weeks while mango fruits inside LDPE packaging film found CO2 injury symptom due to excess CO2 at the third week of storage. For six weeks after storage the chosen composite film delayed green color variation, peduncle drop, and CO2 injury symptom of lime fruits more than neat LDPE film for lime fruits packing for six weeks.