Immobilization of red anthocyanin extract of Dendrobium Sonia ‘Red Bom’ in calcium alginate beads

By using different concentrations of alginate and calcium chloride solutions, calcium alginate beads (CAB) of different sizes and shapes were prepared. Macro-CAB were spherical and of size 1.33 mm and micro-CAB were oblong shape of size 0.45×0.22 mm as determined by SEM. For ease of handling and storage of natural colorant, the red anthocyanin extract from Dendrobium Sonia ‘Red Bom’ (DSAE) orchid flower were immobilized by loading into these beads to produce red colored beads. The morphologies and sizes of the blank and red CAB were examined and determined by SEM. The red macro-CAB were found to be significantly smaller than the blank macro-CAB while the blank and red micro-CAB were similar in sizes. Loading efficiency of macro-CAB was higher than the micro-CAB and the color of red macro-CAB was more intense and brightly colored than the red micro-CAB. Release studies showed that the immobilized red DSAE were released instantaneously from macro- and micro-CAB into the solution. Therefore red CAB can be used to dye a variety of food, cosmetic and pharmaceutical products. Immobilization of red DSAE in calcium alginate beads provides an easy means of handling, storing and ready application of the natural red anthocyanins colorant for intended applications.