Pullulan is a natural polysaccharide with a linear structure comprising repeating a-1 ,6-linked maltotriose molecules which elaborated by a black yeast, Aureobasidium pullulans . Pullulan, a tasteless, oderless, and edible white fine powder, is a natural glucan as are amylose , dextran, and cellulose, but dissolves readily in cold water to form a viscous, non-gelling , aqueou solution.