Structure preservation of Aloe vera (barbadensis Miller) mucilage in a spray drying process

- Linear viscoelastic data for SD Aloe vera mucilage showed weak gel characteristics.
- Aqueous solutions of Aloe vera showed similar elastic properties as fresh mucilage.
- The best spray drying conditions minimized the degradation of fresh mucilage.
- Structure preservation (random coil configuration) was achieved.
- Antioxidant properties of fresh mucilage are preserved at the best drying conditions.

Aloe vera (barbadensis Miller) mucilage in powder form was obtained by spray-drying following by suspension in aqueous solution, to enable microstructure recovery. The rheological behavior of the reconstituted mucilage was evaluated as a function of mucilage concentration, temperature, pH and ionic-strength. Mucilage solutions exhibited shear-thinning non-Newtonian behavior. The viscosity was found dependent on ionic-strength. This dependence is more evident when divalent cations are used, although a strong rise in viscosity upon increasing pH is observed. Linear viscoelastic data show a predominant viscous behavior, but with a crossover point (storage module G′ = loss module G″) suggesting a change in molecular conformation to a random-coil arrangement of the mucilage microstructure. The spray-dried powders were compared with fresh mucilage, with regard to chemical composition and mechanical flow behavior. Results reveal a small structure modification during the spray-drying process, evidencing preservation of the mucilage microstructure when optimum spray-drying conditions are used, i.e., 1.5 L/h inlet flow, temperature of 150 °C and atomization rate of 27,500 rpm.