Porosity of Whey Protein‐Based Microcapsules Containing Anhydrous Milkfat Measured by Gas Displacement Pycnometry

Porosity characteristics of spray‐dried microcapsules consisting of whey proteins and anhydrous milkfat were investigated by gas displacement technique, using helium and nitrogen as displacing gases. Microcapsules exhibited molecular‐sieve type porosity. True and apparent densities as well as porosity characteristics were affected by wall solids concentration and by core load. Results indicated that about 10% of capsule volume was not accessible to helium. Pore volume inaccessible to nitrogen penetration was affected by core load and solid concentration. Results suggested that porosity, and hence gas‐permeation into microcapsules, could be tailored by adjusting microcapsules composition.