Scale-up and optimization of the spray drying conditions for the development of functional microparticles based on chia oil

Abstract

A factorial design was performed for the microencapsulation of chia oil by spray drying at pilot-scale, to validate the results obtained previously at laboratory scale in a Büchi-B290. The effects of drying-air inlet (Tinlet) and outlet (Toutlet) temperatures in a Niro Production Minor on the solid yield, thermal efficiency, theoretical droplet evaporation times, and physico-chemical properties of powders were analyzed. The theoretical droplet evaporation times (0.31−0.54 s) were calculated considering the constant and falling rate periods and a negligible relative velocity between spray and air. Critical diameters between 31.77–41.57 μm were estimated for microcapsules, depending on the process conditions. After scale-up of the spray drying operation, higher solid yields (74.24–79.79%), thermal efficiencies (27.56–73.19%), encapsulation efficiencies (96.97–98.57%), and enhanced flowability of products, compared with experiments at laboratory scale, were observed. Moreover, the scale-up did not affect the chemical composition of microencapsulated oils, their fatty acid composition before and after in-vitro digestion processes. A global optimization was performed at pilot-scale and the process conditions that simultaneously optimized all the responses was 160 °C × 90 °C (Tinlet × Toutlet).