Submitted to: American Institute of Chemical Engineers Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: November 14, 1996
Publication Date: N/A
Technical Abstract: Multi-angle laser light-scattering and viscosity measurements were used to obtain weight average molecular weights, Mw, radii of gyration, Rg, and intrinsic viscosity values, [eta], for waxy maize starches processed by different techniques. Processing methods, including gentle dispersion/solubilization in 90%DMSO-H2O, extrusion, or steam jet-cooking, yielded ranges of values in 90%DMSO-H2O as follows: Mw; (30-330) x 10**6 D; Rg, (98-240) nm; [eta], (0.79-2.0) ml/g at 25 deg C. Our data demonstrated significantly greater variability when the products of starch granule processing had Mw values > 150 x 10**6 D. From these measurements and previous rheological data we conclude that the molecular weight and geometry of amylopectin species in solution are highly dependent upon the technique used to disperse the starch granule. Under conditions where relatively gently conditions were used, our measurements show that significantly different distributions of very high molecular weight products were obtained. Thus, we conclude that there exists a region of initial granule solubilization wherein the characteristics of the amylopectin in solution are highly dependent upon the processing method.