Diffusion coefficient determination to evaluate the release of red ginger oleoresin from the chitosan microcapsules

Abstract

This study aimed to determine the amount of red ginger oleoresin released from the chitosan microcapsules cross-linked with the sodium tripolyphosphate (TPP) and to determine its diffusivity coefficient based on the effect of the chitosan concentration, TPP solution concentration, and pH level. The red ginger oleoresin microcapsules were prepared using the emulsion cross-linking method. The preparation of the microcapsule was initiated by mixing the red ginger oleoresin with the chitosan solution, which was then stirred to form the first emulsion. Afterward, it was added to the oil and stirred again to form the second emulsion. The TPP solution dripped slowly. After the process was complete, it was continued with the addition of acetic acid to adjust the pH level. The formed microcapsules were washed and dried, and the release of the red ginger oleoresin was analyzed in a phosphate buffer medium. This research has been successfully carried out at various affecting factors such as the concentration of chitosan and TPP, and pH level. An increase in the concentration of chitosan and TPP solutions decreased the amount of red ginger oleoresin released from the microcapsules. In a variation of pH level, an increase in pH level from 4 to 5 decreased the cumulative release of red ginger oleoresin, but an increase in pH level from 5 to 6 increased the cumulative release value. The highest and the lowest cumulative release values were 65.06 ±1.54% and 48.82±2.1%, respectively. The values of diffusion coefficients were from 3.49 10^-10 to 4.86 10^-10 .