PLASTICIZED WHEY-PROTEIN EDIBLE FILMS - WATER-VAPOR PERMEABILITY PROPERTIES

Heat treatment, protein concentration, and pH effects on water vapor permeability (WVP) of plasticized whey protein films were examined. The best film formation conditions were neutral pH, aqueous 10% (w/w) protein solutions heated for 30 min at 90 degrees C. Isoelectric point adjustment of whey protein with calcium ascorbate buffer increased WVP with increasing buffer concentration. The importance of vacuum application to minimize film pore size was identified using scanning electron microscopy. Polyethylene glycol, glycerol and sorbitol plasticizer concentration affected film WW. Determining the effects of relative humidity on WVP for plasticized whey protein films enabled prediction of film behavior under any water vapor partial pressure gradient.