Ethylene adsorption on chitosan/zeolite composite films for packaging applications

Abstract

• A film of chitosan and natural zeolite has been evaluated for ethylene release control. • Ethylene equilibrium of adsorption was measured gravimetrically. • Ethylene adsorption capacity was affected by zeolite amount and film drying process. • Chitosan/zeolite film chose for ethylene is based on the product to be packed. Ethylene is the hormone responsible for the development and ripening of fruits and vegetables. Thus, in order to extend the postharvest shelf life, its accumulation should be avoided. Films, dense and porous, composed of chitosan/zeolite (CZ), were obtained using chitosan as support for clinoptilolite zeolites. These films were characterized by nitrogen and carbon dioxide adsorption isotherms, water vapor permeability and ethylene adsorption capacity. Zeolites distribution and the development of the pores were observed by scanning electron microscopy. Films were dried (partially or totally) by a convective process, followed or not by lyophilization. Lyophilized-CZ (with 93 % zeolite (CZ93 L) showed adsorption capacity similar to that of pure zeolite regenerated at 90 °C (ZR90) and higher than CZ93. Dense-chitosan films (DCF), porous-chitosan films (PCF) and CZ33 (33 % zeolite) exhibited small amounts of adsorbed ethylene when compared to the other materials. Based on these results, the chitosan/zeolite films may be viable for packaging applications.