Chapter 6 - Encapsulation: Spray chilling and cooling

Abstract

The process of solidifying an atomized mixture containing an active agent and a molten carrier into particles at the temperature lower than the melting point of the carrier is named spray chilling. This process is appropriate for making particles from a few microns to several millimeters and suggested as spray cooling, spray congealing, or prilling. In spray cooling/chilling, the melt is atomized and cool down without mass transfer. In addition, there is commonly no water in spray cooling/chilling process to be evaporated. By applying spray chilling, it is possible to prepare microspheres. Microspheres are the most usual encapsulation morphology in which an active component is homogeneously dispersed all over the encapsulating matrix. Fats, waxes, lipids, and gelling hydrocolloids are usual matrix. The spray cooling techniques usually have high throughput and low cost and are easy to functionalize. Different factors impact on the particle size in the solidification process. The size of nozzle, rotary speed, and prilling wheel speed are some of the key parameters for particle size adjustment. Also, diversity of atomization routes is accessible such as pressure nozzles, vibrating nozzles, and spinning disk atomizers. In this chapter, at first, we introduce spray chilling/spray cooling process and their difference to each other. Then, the constructed materials and important parameters on the particle size will be determined. The main analysis for particles characterization will be reported. Moreover, the active agents that are encapsulated by this method will be reviewed. Finally, the future trend of this technique will be discussed.