The prediction model of nozzle height in liquid jet‐drop method to produce Ca‐alginate beads under microencapsulation process

Abstract

AbstractThe models for prediction of nozzle height on Ca‐alginate bead formation developed previously for drop‐by‐drop process depending on the information of Oh number that is difficult to apply to liquid jet‐drop process due to the uncertainty of available models for droplet diameter prediction. In this study, the models for the prediction of nozzle height to obtain acceptable bead sphericity in the liquid jet‐drop process were developed without the need for droplet diameter information. The experiments were conducted for alginate concentrations of 1.5%–3%, liquid flow rates of 4–10 mL/min, and nozzle heights of 6–195 cm to study the size and sphericity of beads and microencapsulation yield (MEY) of lime oil. The generation of pulsation formed a smooth liquid jet‐drop process in which nozzle height, alginate concentration, and liquid flow rate had a significant effect on the bead size and sphericity but not on MEY. The optimum nozzle height at 94%–95% sphericity was found to correlate well with the Oh number. The optimum nozzle height for low viscosity liquid (<80 mPa·s) was less than 19 cm and for high‐viscosity liquid (>190 mPa·s) was 35–135 cm depending on the viscosity.Practical applicationsThe application of microencapsulation in the food industry has been recognized widely as a method to protect active compounds from heat, light, and oxidation during manufacture and preservation. It can also be used to control the release of compounds or change the structure of the products. Vibration technology has been applied widely in microencapsulation concerning the production of high spherical beads for a better and precise controlled release. However, there is no available information about the effect of nozzle height on the sphericity of beads in this technology, especially for high viscosity and high shear rate operations. This study provided a model for the prediction of nozzle height to satisfy acceptable sphericity of beads in this technology with low‐frequency case.