Submitted to: International Light Scattering Colloquium
Publication Type: Abstract Only
Publication Acceptance Date: September 23, 2003
Publication Date: September 23, 2003
Citation: Ahlgren, J.A., Leathers, T.D., Nunnally, M.S., Cote, G.L. 2003. Application of mals in the characterization of a novel polysaccharide, modified alternan [abstract]. International Light Scattering Colloquium. Paper No. 4. Technical Abstract: Alternan is a branched glucan with a unique backbone structure of alternating alpha-(1-6) and alpha-(1-3) linkages, produced by certain strains of the bacterium Leuconostoc mesenteroides. Recently, novel strains of Penicillium sp. were isolated that quantitatively modify alternan to lower apparent molecular weight forms with solution viscosity properties that resemble those of gum arabic (U.S. Patent 6,479,275). Gum arabic is exclusively imported, and it would be desirable to have a domestic alternative of consistent quality and price. Modified alternan was further characterized to evaluate its potential for commercial applications. The molar mass and size of native and modified alternan were analyzed by multi-angle light scattering and refractive index during separation by high performance liquid size exclusion chromatography (HPLC SEC-MALS). Native alternan exhibits a high degree of light scattering which is progressively reduced by modification, characteristic of polymer degradation. Concurrent detection by RI shows native alternan as a high molecular weight polymer that is progressively modified to lower molecular weight, heterodisperse forms. Modified alternan exhibits a linkage pattern similar to that of native alternan. The solution viscosity properties of modified alternan resemble those of ultrasonicated alternan and commercial gum arabic, although alternan lacks the emulsification capacity of gum arabic. Alternan solutions are extremely stable at 4-37 deg C and at pH 3-9. Dry preparations of alternan are bright white, tasteless powders that are not highly hygroscopic. Thus, modified alternan is promising for further development as a gum arabic substitute. More detailed conformational studies on native and modified alternan are underway.