35. Starch: Structure, Properties, Chemistry, and Enzymology

Starch is a very important and widely distributed natural product, occurring in the leaves of green plants, seeds, fruits, stems, roots, and tubers. It serves as the chemical storage form of the energy of the sun and is the primary source of energy for the organisms on the Earth. Starch is composed of two kinds of polysaccharides, amylose and amylopectin, exclusively composed of d‑glucose residues with α‑(1→4) linkages in a linear amylose and α‑(1→4) linkages and ∼5% α‑(1→6) branch linkages in amylopectin, both combined in a water‐insoluble granule that is partially crystalline and whose size, shape, and morphology are dependent on its biological source. The properties, isolation, fractionation, enzymatic degradation, biosynthesis, chemical modification, and specific methods of analysis of starch are presented.