Characterization of cross-linked chitosan by ionic and covalent crosslinking agents as wall material of red ginger oleoresin microcapsules

The aim of this study was to determine the characterization of ionic and covalent interactions to form a crosslinking network with chitosan as a wall material of microcapsules. Red ginger oleoresin microcapsule was prepared by emulsion crosslinking method. Red ginger oleoresin was mixed and stirred with chitosan solution to form an emulsion, then added to corn oil and stirred again to form a second emulsion. Crosslinking agents of glutaraldehyde saturated toluene (GST) or sodium tripolyphosphate (TPP) solution was slowly added to the emulsion. When using a crosslinking agent of TPP solution was added glacial acetic acid to adjust pH. Red ginger oleoresin microcapsules were filtered and washed with petroleum ether followed by n-hexane and then dried in an oven. Microcapsules from chitosan that are cross-linked with GST produce higher yield and size of microcapsules compared to TPP. Whereas, the highest encapsulation efficiency produced from chitosan cross-linked with TPP was 91.63±0.02%. Meanwhile, the highest cumulative release was obtained from TPP cross-linked chitosan microcapsules of 63.71% and the lowest was 50.01% from chitosan microcapsules that cross-linked with GST. The conclusion of this study was the differences between ionic and covalent crosslinking agents produce different microcapsule characteristics. Microcapsules from chitosan cross-linked with GST generated more compact with a smoother surface than with TPP.