306 Properties of industrial starches.

W. VORWERG (1), S. RADOSTA (1), A. KRÖGER (1), and M. G. LINDHAUER (2). (1) Fraunhofer-Institute for Applied Polymer Research, Teltow, Germany; (2) Federal Centre for Cereal, Potato and Lipid Research, Detmold, Germany.

Industrial starch of several production lines from potato, corn and wheat where investigated to get information about the range of the amylose/amylopectin ratio, the particle size distribution as well as about molecular composition and rheological behavior. Molecular weight distribution were investigated in the solvent water and DMSO by size exclusion chromatography with multi angle laser light scattering detector. Rheological properties were compared after gelatinisation of concentrated aqueous solutions at the temperature of 95 C. Flow behavior were determined at 90 C, gelation process were followed by cooling up to 5 C and gel properties were measured after the time of about 20h. The granules of potato starch have sizes in the range of 20–150 µm, wheat starch 12–51 µm and corn starch 2–21 µm. The average of molecular weight of well dissolved starches were found between 20E6 and 60E6 g/mol. Relative viscosity is strongly dependent on shear stress at all investigated starches. Gel strength describing as storage modulus was lower at potato starch gels than at wheat and corn starch gels. However the deformation ability was much more higher of potato starch than of wheat and corn starch gels. The variation of measured data will be discussed to compare the different genotyps.