Cereal Chem 63:287-291   |  VIEW ARTICLE
An Electron Spin Resonance Study of Native and Gelatinized Starch Systems.

N. L. Nolan, J. M. Faubion, and R. C. Hoseney. Copyright 1986 by the American Association of Cereal Chemists, Inc. 

Wheat, corn and waxy corn starches were slurried at three water/starch ratios (0.5:1, 1:1, and 2:1), with a hydrophobic probe, TEMPO-laurate, and a hydrophilic probe, TEMPO. Samples containing TEMPO at the two higher water ratios gave electron spin resonance (ESR) signals that were symmetrical and that had high tumbling rates. At the low water/starch ratio, the signals became distorted and tumbling create decreased. For the 1:1 and 2:1 samples, the ESR signal was an average of that for the probe inside and outside the starch granules. A probe-binding study revealed that TEMPO-laurate and 16-DOXYL stearic acid were readily washed from starch with either but were bound to the starch in the presence of water. ESR spectra of the TEMPO-laurate or 16-DOXYL stearic acid plus starches had distorted line shapes and tumbling rates clustered in the range of 10(8)/sec. This differed greatly from the results obtained using TEMPO, and verified probe binding. The molecular motion of TEMPO-laurate and 16-DOXYL stearic acid was not dependent on the amount of water in the starch-probe system. Addition of amylose or amylopectin to TEMPO-laurate in water resulted in distorted spectra with lower values for tumbling rates, suggesting that the probe was bound to both polymers.