Preparation of microcapsules by electrostatic atomization

A new method for preparing microcapsules based on a one-step gelling process combined with an electrostatic atomization technique is proposed. In the process, capsules with polymer shells are produced by dripping viscous solution, which contains a crosslinker agent, into a consolidation solution with agitation. In this study, sodium alginate and CaCl2 were used as a polymer material for shell formation and crosslinker agent, respectively. Carboxymethyl cellulose (CMC) was used as a non-gelling polymer to modulate the viscosity and the density of the core solution to prevent deformation during the shell formation process. The CMC in the core of the capsule obtained was then enzymatically decomposed using cellulase. The results show that the microcapsules with alginate shell and water core are obtained successfully. By combining the one-step gelling process with the electrostatic atomization technique, the capsule size can be reduced to 500 μm in diameter. To demonstrate a practical application, enzyme immobilization was performed within the capsules. Invertase, which catalyzes the decomposition of sucrose into fructose and glucose, was used as a model enzyme in this study. The results show that invertase is immobilized with high efficiency (87–98%). Enzyme activity is increased with increasing of the applied voltage in the electro-dripping process because of the smaller capsule diameter at the higher applied voltage.