Influence of the spray drying operating conditions on the estimated drying kinetics of emulsion single droplets and the properties of microencapsulated chia oil

Abstract

The main objective of this research was to study the chia oil microencapsulation process in a co-current spray dryer. First, the effects of drying air inlet temperature and volumetric feed rate on the air temperature along the dryer, solid yield, physical properties of powders, and the estimated droplet evaporation time were assessed. Second, the evaporation time was predicted by means of a simple fundamental model, based on evaporation in still air and the constant rate period. Third, a global optimization of drying process conditions was performed. The main results showed that a uniform air temperature was found inside the dryer for all the process conditions, evidencing a well-mixed chamber. The estimated values of droplet evaporation times were between 1.23 and 2.55 s. Strong correlations between evaporation times and physical properties of powders (moisture content, surface oil content and encapsulation efficiency) were found. Finally, the process condition that simultaneously optimized dependent variables was 130 °C x 10 mL/min.