Optimization of Microcapsule Production by Air Atomization Technique using Two-Fluid Nozzle

A method of preparing microcapsules using two-fluid glass nozzle was studied for microencapsulation of food ingredients. In this method, a solution of sodium alginate and starch was sprayed using a two-fluid glass nozzle into a reaction vessel containing calcium chloride gelling bath. The aim of this work was to study the effect of some process variables on particle size of microcapsules. Response Surface Methodology by applying Box-Behnken design was used to optimize four independent variables viz., sodium alginate concentration (% w/v), starch concentration (% w/v), pressure (bar), and flow rate (ml/min) for obtaining target particle size. The ANOVA of the regression model demonstrated that the model was highly significant and adequate (p = 0.0054, R 2 = 0.8837). The microcapsules produced have average particle size ranging from 104.56 to 734.69 μm. The results revealed that concentration of sodium alginate solution and air pressure used for atomization had significant effect on particle size of microcapsules (p < 0.01). The optimized formulation and experimental conditions (sodium alginate concentration (2 % w/v), starch concentration (3 % w/v), air pressure (0.75 bar), and flow rate (80 ml/min)) yielded microcapsules of particle size values very close to predicted particle size. The morphology of microcapsules confirmed the near spherical capsular structure; which indicated that two-fluid glass nozzle can be used for production of spherical microcapsules.