Coacervate microcapsules of vitamin U optimized by central composite design (CCD)

Abstract

The purpose of this study was to prepare microcapsules encapsulating vitamin U (VU, S-methylmethionine) by complex coacervation. Multiple emulsion method was applied for encapsulating highly water-soluble VU. The composition of microcapsules was optimized using central composite design (CCD). The weight ratio of gelatin to gum arabic (X1) and the volume of oil phase (X2) were set as two independent variables to obtain the maximum weight of microcapsules (Y1) and the content of VU (Y2) in microcapsules higher than 2.5%. When the microcapsules were prepared based on the optimized composition, its actual Y1 and Y2 values were 95% of the predicted values. Morphology of microcapsules observed by the optical and the fluorescence microscopes was round shape. Scanning electron microscopy (SEM) image of internal particles also confirmed that the multiple emulsions were encapsulated in the microcapules. Mean particle size of microcapsules measured by the laser diffraction particle size analyzer was 79.17µm. Differential scanning calorimetry (DSC) showed that VU exists in an amorphous state in the coacervate microcapsules. Thus, it can be concluded that hydrophilic VU was successfully encapsulated in the coacervate microcapsules using the multiple emulsion method, and the design of experiment (DoE) technique was useful to optimize the formulation. © 2018, The Korean Society of Pharmaceutical Sciences and Technology.