CHARACTERIZATION OF BRANCHING CHARACTERISTICS OF STARCH-GLUCANS BY MEANS OF COMBINED APPLICATION OF COMPLEXATION, ENZYMATICALLY CATALYZED MODIFICATION, AND LIQUID-CHROMATOGRAPHY

Molecular characteristics, especially the branching-structure, of gluc ans from starch granules isolated from tubers of potato species Ukomo are determined. Granule-fraction with different mean-diameters are pro vided by sedimentation as inital separation step for further investiga tions. Then aqueous/DMSO dissolved starch glucans were separated into a non-branched/long-chain-branched and a short-chain-branched fraction by precipitation with n-butanol and methanol, respectively. By means of preparative SEC glucan pools of these fractions were collected and as well analyzed by means of methylation/GC-MS as checked for their in dividual potential to complex with polyiodide anions. Additionally equ ivaalents of these fractions were debranched by the catalytic action o f pullulanase to determine the constituting glucan chain distribution by means of analytical SEC. Results of branching characteristics in te rms of average number of monomers between two adjacent branching posit ions (bp-->bp), average percentage of branching (b%) and E(640)/E(525) (nb/lcb / scb)-ratio from different techniques are in good agreement a nd yield significantly different values for glucans from large and sma ll starch-granules.