Drying temperature effect on water vapor permeability and mechanical properties of whey protein-lipid emulsion films

The water vapor permeability (WVP) and mechanical properties of whey protein isolate (WPI) and WPI-lipid emulsion films dried at different conditions were investigated. As drying temperature increased, WVPs decreased significantly. Significantly lower WVP was observed for emulsion films compared to WPI films. WPI-Beeswax (BW) and WPI-anhydrous milkfat fraction emulsion films dried at 80 degrees C and 40% RH gave the lowest WVP compared to 25 degrees C, 40% RH and 40 degrees C, 40% RH. A large drop in WVP of WPI-BW emulsion films was observed at 20% BW content. The decrease in WVP for emulsion films as drying temperature increased could be due to change in the lipid crystalline morphology and/or lipid distribution within the matrix. Mechanical properties of WPI and WPI-lipid emulsion films, on the other hand, were not modified by drying conditions.