Structure and attribute modifications of spray-dried skim milk powder treated by DIC (instant controlled pressure drop) technology

Expanding the texture of granules can generally completely modify the functional behaviour of powder. The present study aimed to identify granule structure and quality attribute modifications of spray-dried skim milk powders after an instant controlled pressure-drop (DIC) treatment, which might be considered as a texturing stage inserted in a classic spray-drying process. Two versions of DIC, high air pressure (HAP-DIC) and low steam pressure (STEAM-DIC), were alternatively used. Response Surface Method experimental design was achieved with DIC pressure, treatment time, and moisture content as independent variables. The analyses of the technological, physical, and structural properties of untreated and DIC-textured powders were carried out and considered as response dependent variables. The results illustrated that whatever the type of DIC, the optimized DIC treatment implied a controlled increase in porosity, interstitial air volume, and compressibility, as well as specific surface area and reconstitution aptitude