Acetone release during thin film drying of maltodextrin solutions as model system for spray drying

Spray drying is an effective method to encapsulate volatile compounds in a carrier matrix. The exact mechanism of volatile retention during spray drying is not well understood but could facilitate optimization of the drying process and contribute to better formulation of the encapsulation matrix. Therefore, a thin film dryer equipped with a photo-ionisation detector was constructed to measure online the volatile release and drying kinetics of maltodextrin solutions with acetone. Thin films of maltodextrin-acetone mixture were exposed to drying air for 1 h at 105 degrees C. The acetone release occurred mostly during the first 10 min of drying which aligned with the constant drying period. This period decreased for films containing higher initial solids as the falling rate period started earlier. Maltodextrin DE12 films retained more acetone than DE21, thanks to its higher viscosity lowered acetone diffusivity. A mechanistic drying model was developed that confirmed the observed correlations between acetone release and drying kinetics.