Production And Characterization Of Styralyl Acetate Loaded Microcapsules By Complex Cocervation

In present work, the styralyl acetate loaded microcapsules were prepared by complex coacervation using gelatin and gum Arabic as wall materials. Single factor experiments and response surface methodology were carried out to explore the optimal processing conditions. The physical and chemical properties of the optimal styralyl acetate loaded microcapsules were characterized by an optical microscope, Ultraviolet spectrum, Fourier transform infrared (FT-IR), Scanning Electron Microscopy (SEM), X-ray diffraction, nuclear magnetic resonance (NMR) and thermogravimetric analysis (TGA).Effects of pH, wall concentration, the amount of core oil and crosslinking on the particle size, morphological structure, yield, encapsulation efficiency and oil loading of microcapsules through single factor experiments. Moreover, the optimal processing conditions were evaluated using central composite design (CCD) in response surface design (RSM). In RSM, the wall concentration and the amount of core oil were chosen as two independent variables, and the yield, encapsulation efficiency and oil loading were determined as three response variables. An optimal processing conditions obtained was pH of 4.4, wall concentration (a gelatin and gum Arabic concentration respectively) of 1.35%, a styralyl acetate amount of 2.23g. a crosslinking amount of 0.25g and the harden time of 3h, which provided the greasted yield, encapsulation efficiency and oil loading of 72.8%,80.6% and 66.2%, respectively. The particle size of wet microcapsule obtained from the optimal conditions was 49μm in a narrow distribution. The morphology of freezing dried microcapsules observed by SEM was spherical shape with smooth surface, and the particle size of dried microcapsules was about 40μm.Structures and properties of the optimal microcapsules were studied, all results showed that the structure of styralyl acetate loaded microcapsules didn’t changed, which were prepared by complex coacervation with gelatin and gum Arabic as wall materials, suggesting only physical interactions occurred between wall materials and core oil. Furthermore, microcapsules presented excellent heat-resistance owing to the volatilization temperature of styralyl acetate was enchanced from 150℃ to 300℃. In addition, dried microcapsules followed zero order release kinetics equation when they were put in heat air for more than 20 min, and wet microcapsules followed the first order release kinetis equation.