Structural factors responsible for the permeability of water vapor through fat barrier films

The influence of structure on the water vapor permeability (WVP) of fat films was determined in this study. Statistically significant (P < 0.1) correlations were found between WVP and chemical composition (% stearic acid), the Avrami index (n), the half-time of crystallization (t1/2), the maximum solid fat content, and crystalline domain size determined by powder X-ray diffraction (XS). Larger domain sizes translate into a smaller grain boundary surface area through which water vapor can migrate, resulting in a lower WVP. High values of XS were associated with fats with high SFC and stearic acid contents. These fats also crystallize rapidly, with low n and t1/2 values.