Microencapsulation of Sodium Bicarbonate Based on Glycerol Monostearate and Konjac Glucomannan Wall Systems by Phase Separation

Abstract

Sodium bicarbonate microcapsules (SBCM) were prepared by phase separation method using glycerol monostearate (GMS) and konjac glucomannan (KGM) as wall materials. Microscope micrographs clearly showed that SBCM microcapsules were spherical shapes, and the microcapsule morphology could not be changed at 40°C, while it could be destroyed at temperature above 60°C. DSC thermograms implied that SBCM wall materials could be melted at temperature about 59°C. Size distribution indicated that the particle size of SBCM was mainly distributed in the range of 50 µm to 300 µm. SBCM stability was evaluated using the percentage of SBC (sodium bicarbonate) retention, i.e. retention ratio. SBC retention ratio showed that SBCM was highly stable in the temperature range 40–80°C. Furthermore, carbon dioxide (CO₂) release efficiency of SBCM was investigated by pairing the microcapsules with monopotassium phosphate. The CO₂ release ratio of SBCM was very low at temperature below 60°C. However, the release ratio was sharply increased at temperature above 60°C, and CO₂ was almost completely released at 60°C for 10 min. According to the results, the CO₂ release of SBC could be effectively controlled by encapsulating into microcapsules based on GMS/KGM wall materials.