ABSTRACT
To fully understand and appreciate the versatility of starch polymers and their applications in bioplastics, and to serve the interest of the readership, some background information on the physical and chemical properties of starch is reviewed here. Starches used in industrial applications are usually extracted from cereal seeds (corn, wheat, and rice), tubers (potato), and roots (tapioca). Starches from various sources are chemically similar, yet their granules are heterogeneous with respect to their size, shape, and molecular constituents.1,2 Probably their most critical descriptor is their proportion of the polysaccharides amylose and amylopectin.1,2 The chemical structures of amylose and amylopectin are shown in Figure 20.1. Naturally occurring types of cereal endosperm starches contain 72-82% by weight of amylopectin and 18-33% by weight of amylose.
