Description

Abstract: This study was conducted to determine water sorption isotherms of cellulose-based films made from methyl cellulose (MC) and hydroxypropyl cellulose (HPC), and to evaluate the efsect of plasticizer concentration and temperature on water vapor permeability coeflcient in those films. The equilib~umm oisture Contents of MCfilm and HPCfilm increased slowly with an increase in water activity (a,) up to 0.75, but increased greatly after 0.75 a,. The water vapor permeability coeflcient of HPC film increased as the concentration ofpolyethylene glycol (PEG) increased; however, the water vapor permeability coefficient of MC film which contained 0.22 ml PEG& cellulose was lower than of films which contained no or higher PEG. An Arrhenius-rype relationship was fitted to examine temperature dependence of water vapor permeability coefficients of cellulose films. The edible films studied exhibited relatively low activation energies (14.56-1 6.43 kJ/mol) compared with typical food packaging materials.