Submitted to: Biopolymers
Publication Type: Book / Chapter
Publication Acceptance Date: June 19, 2001
Publication Date: January 1, 2002
Citation: COTE, G.L. ALTERNAN. VANDAMME, E.J., DE BAETS, S., STEINBUCHEL, A., EDITORS. WILEY-VCH, WEINHEIM. BIOPOLYMERS; CHAPTER 13. 2002. P. 323-350. Technical Abstract: This comprehensive review describes the structure, properties, and potential applications of the unique microbial gum known as alternan. Alternan is an alpha-D-glucan consisting of alternating (1-3) and (1-6) linkages. It is produced by an extracellular enzyme from certain strains of Leuconostoc mesenteroides. The enzyme, alternansucrase, polymerizes the eD-glucose moiety of sucrose into alternan and releases D-fructose. Alternan is very water-soluble and possesses remarkably low viscosity considering its high molecular weight. Due to its unusual alternating linkage structure, it is resistant to digestion by most hydrolytic enzymes. Two enzymes are known to degrade alternan to oligosaccharides. Isomaltodextranase converts alternan mainly to isomaltose and a limit alternan. The limit alternan is similar to polydextrose in solubility and other properties. Alternanase hydrolyzes alternan endolytically to give a mixture of oligosaccharides. The major product is a novel cyclic tetrasaccharide. Several potential applications of alternan and its degradation products are described, including gum arabic substitutes, noncaloric bulking agents, prebiotic dietary supplements, and papermaking aids.