Preparation and characterization of shellac-coated anthocyanin pectin beads as dietary colonic delivery system

Scope: Anthocyanins are connected with various biological activities. A promising way to enhance the availability of anthocyanins for in situ effects in the lower intestine is colon-specific delivery. Methods and results: Shellac and shellac/hydroxypropyl methylcellulose (HPMC) coated anthocyanin amidated pectin beads as dietary colonic delivery systems were successfully prepared by ionotropic gelation and fluid bed Wurster coating with aqueous shellac solution. Release characteristics, studied in vitro and ex vivo using simulated gastric fluid (SGF), ileostomy fluid and colostomy fluid (CF) revealed a retardation of anthocyanins during simulated passage of stomach and ileum as well as the desired release of pigments in the colon. Coating level was identified as an important parameter. By addition of 5 or 15% of the water-soluble polysaccharide HPMC to the shellac film, resistance in SGF was increased due to the plasticizer properties of the polymer. Incorporation of 15% HPMC (w/w based on shellac) into the shellac film additionally led to increased anthocyanin diffusivity and complete release as well as degradation of the formulation in CF. Conclusion: In the used in vitro and ex vivo model system mimicking the human intestinal transit, the potential of shellac and shellac/HPMC coated anthocyanin amidated pectin beads as dietary colon targeting systems was demonstrated.