Microstructural properties and distribution of components in microparticles obtained by spray-drying

The aim of this work was to analyse the relationship between microstructural development, distribution of elemental components and characteristics related to functional properties of powders obtained by spray drying process. Blends of soy protein isolate (SPI), gum Arabic (AG) and maltodextrin 20 DE (MD) at 20% TS were prepared and spray-dried at 250 °C, 200 °C, 175 °C and 150 °C as inlet temperatures of drying air, and the outlet temperature at 70 °C was kept constant. Bulk density, hygroscopicity and wetting time were affected by concentration of wall material, drying air temperature did not suggest effect on these characteristics. Using combined microscopy techniques, the internal microstructure of particles obtained at 150 °C/70° as inlet/outlet drying air temperatures were analysed, results revealed that 26% was the highest percentage of hollow microparticles and the shell thickness from 264 nm to 290 nm. In these microparticles, the elemental analysis revealed that nitrogen was present from 2.93% to 15.37% in particles surface. Additional, a descriptive model to explain the possible assemble of wall material of a microparticle was proposed.