Formulation and characterization of chitosan-alginate freeze dried matrices loaded with oleoresin extract of red ginger

A simple method of encapsulation of bioactive compounds that does not involve washing, heating, and degradation of active substance is desired. The encapsulation of red ginger oleoresin in the chitosan-alginate matrix was developed using the freeze drying method to achieve higher matrix yield and loading capacity in the matrix. Bioactive substances that are encapsulated in the chitosan-alginate matrix aim to be released in the colon. Oleoresin red ginger extract was obtained from maceration of dried rhizome powder in ethanol. A mixed solution consisting of chitosan, oleoresin extract, Tween 80 as a surfactant and alginate was lyophilized at-50 C at a vacuum pressure of about 20 atm for 48-72 hours. The X-ray diffraction pattern of the formed matrix shows that the crystalline chitosan and alginate peaks disappear in the chitosan-alginate matrix which shows compatibility. In the Infra Red matrix spectrum the interaction between chitosan and alginate in the matrix is shown by the change of peak height at 1520 and 1385 cm^-1. Release assay showed that the matrix with a weight ratio of chitosan: Alginate of 1: 0.5 slightly released phenolic compounds from oleoresin in the simulated gastric fluid but highly released in the simulated intestinal and colon fluids.