Characterizing the Size and Molecular Weight Distribution of Starch: Why It Is Important and Why It Is Hard
R. G. Gilbert (1), M. J. Gidley (1), S. Hill (2), P. Kilz (3), A. Rolland-Sabaté (4), D. G. Stevenson (5), and R. A. Cave (6). (1) University of Queensland, Brisbane, Australia. (2) University of Nottingham, Nottingham, U.K. (3) PSS Polymer Standards Service GmbH, Mainz, Germany. (4) Institut National de la Recherche Agronomique, Nantes, France. (5) National Starch, Bridgewater, NJ, U.S.A. (6) University of Queensland, Brisbane, Australia. Cereal Foods World 55(3):139-143.
Starch is one of the most important polymers for humanity: it comprises the largest single component of our food energy, and is also an important industrial polymer, for example, it is used in papermaking, biofuels, and the food and pharmaceutical industries as an additive with diverse uses. On one level, it is simple: a polymer of glucose (or of anhydroglucose, to be more precise). However, it is a mix of two polymer architectures: amylose—largely linear with a few long-chain branches—and amylopectin, which is highly branched. Because of this branching, it shows a bewildering structural complexity. Starch structure (including amylose to amylopectin ratio and other structural features) dictates starch properties, such as how rapidly and where a food is digested, or how well a modified starch might serve as a thickener or dispersing agent. The cereal food industry commonly uses molecular weight as a means of quality assurance. However, things are not that simple.