Preparation and evaluation of chitosan-calcium-gellan gum beads for controlled release of protein

The bead system composed of chitosan and calcium-gellan gum was prepared through a combination of ionotropic gelation and polyelectrolyte complexation for oral protein delivery. The characteristics of beads were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, release studies, and swelling measurements. It was found that chitosan endowed the calcium-gellan gum beads a dense surface and the crystal structure of polymers was disrupted after being combined together. The encapsulation efficiency of protein was in the range of 65-85 %. Higher gellan gum concentration combined with vacuum dryness significantly retarded protein fast release at pH 1.2 and achieved sustained release at pH 6.8, whereas providing efficient release at pH 7.4. The protein release was mainly attributed to Fickian diffusion mechanism in the process of swelling. The chitosan-calcium-gellan gum beads have the potential to act as a new carrier for controlled release of protein-based functional ingredients.