Calculation of the persistence length of solubilized starches from intrinsic viscosity measurements

The persistence lengths for two different commercial starches were estimate d from intrinsic viscosity measurements. The intrinsic viscosities of the s tarches were measured at 25 degrees C using 90/10 dimethy sulfoxide (DMSO)/ water (weight/weight) as the solvent. The calculations were conducted using the equations developed by Yamakawa and Yoshizaki [Macromolecules 13, 633- 633 (1980)] and corrected for polydispersity using the Schultz-Flory distri bution. Values for the persistence lengths were 8.1 +/- 0.6 and 6.6 +/- 0.5 nm for a high-amylose potato, and a high-amylose maize starch, respectivel y. The values for the persistence length obtained for the two starch sample s reflect the stiffness of the amylose chains in DMSO, which is due to the helical conformation of amylose in the solvent. (C) 1999 The Society of Rhe ology. [S0148-6055(99)01703-4].