Surface characterization and dissolution properties of high amylose corn starch–pectin coatings

Coatings from mixture of pectin and high amylose corn starch (HACS) were prepared on glass slides, and characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), dissolution and enzymatic digestion tests. The surface of pectin–HACS coatings showed increased roughness with increase in HACS content (r2=0.957, p≤0.001). Dissolution of the coatings decreased with increase in HACS content in both stomach (pH 1.6) and intestine (pH 7.0) conditions. HACS coatings also showed high resistance to amylolysis, with degradation of <35% after 3 h of incubation in pancreatic solution. SEM images of enzymatically treated HACS coatings revealed a uniform and practically intact surface. The potential of these coatings for targeted release in the intestine was, therefore, demonstrated.