Particle Morphology of Spray-Freeze Dried Microencapsulation Agents

Abstract

Spray-freeze drying (SFD) is a relatively new technique for microencapsulation of heat sensitive products. In SFD process, the solution is sprayed in a cryogenic medium such as liquid nitrogen to form frozen fine droplets. Then, the droplets subjected to freeze-drying under vacuum. The freeze-drying time is comparatively short due to the relatively large surface area achieved by the SFD. In this study, frequently used microencapsulation agents namely maltodextrin, inulin and gum arabic were spray-freeze dried both individual and in the form of mixtures and the resulting powders were characterized with respect to particle morphologies. Morphology of the particles were observed using Scanning Electron Microscopy (SEM). All the spray-freeze dried particles showed spherical shape, sometimes being slightly aggregated. Regular pore structures originating from the formation of crystals were observed on the surface of the maltodextrin particles, while the gum arabic particles were found to have more irregular and small pores. However, inulin particles were found to have a smoother surface form than others.

Keywords: Spray-freeze drying, morphology, inulin, maltodextrin, gum Arabic

DOI: 10.7176/JSTR/5-2-24