Optimization and scale-up of the spray drying process for Euglena gracilis

Abstract

The study presents a spray drying process for Euglena gracilis. Concentrate obtained by a disc centrifuge was used as the starting material. The process was established and scaled up using pilot and production-scale spray drying towers. Optimal conditions for the pilot scale included an inlet temperature of 200 °C, an outlet temperature of 85 °C, and a solid mass fraction of E. gracilis mud of 12 %. Key parameters influencing E. gracilis powder physicochemical indexes were identified by correlation analysis as drying time for droplets (T_drying), which can be adjusted by the outlet air temperature, the Peclet number for mass (Pe_mass), and heat (Pe_heat), and the evaporation rate ($\frac{d_w}{d_t}$), all of which can be adjusted by the outlet temperature. The process was successfully scaled up by optimizing the outlet temperature, achieving a productivity of 36.63 kg·h⁻¹ and a yield of 98.35 %. This work offers a commercially viable method for large-scale E. gracilis powder production.