EFFECT of PLASTICIZER LEVEL and TEMPERATURE ON WATER VAPOR TRANSMISSION of CELLULOSE‐BASED EDIBLE FILMS1

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 effect of plasticizer concentration and temperature on water vapor permeability coefficient in those films. the equilibrium moisture contents of MC film and HPC film increased slowly with an increase in water activity (aw) up to 0.75, but increased greatly after 0.75 aw. the water vapor permeability coefficient of HPC film increased as the concentration of polyethylene glycol (PEG) increased; however, the water vapor permeability coefficient of MC film which contained 0.22 ml PEG/g cellulose was lower than of films which contained no or higher PEG. an Arrhenius‐type relationship was fitted to examine temperature dependence of water vapor permeability coefficients of cellulose films. the edible films studied exhibited relatively low activation energies (14.56–16.43 kJ/mol) compared with typical food packaging materials.