Cereal Chem 68:238-244   |  VIEW ARTICLE

Application of High-Resolution Carbon-13, Oxygen-17, and Sodium-23 Nuclear Magnetic Resonance to Study the Influences of Water, Sucrose, and Sodium Chloride on Starch Gelatinization.

P. Chinachoti, V. A. White, L. Lo, and T. R. Stengle. Copyright 1991 by the American Association of Cereal Chemists, Inc. 

Nuclear magnetic resonance (NMR) spectroscopy was used to observe molecular changes during thermal transition of wheat starch in free water (D2O) in the presence of sucrose and sodium using the nuclei of carbon-13, oxygen-17, and sodium-23. A starch-D2O mixture (40:60) was heated from 25 to 95 C and then cooled back to 25 C. Pulse NMR spectra obtained on heating and cooling showed a drastic increase in the 13C signal intensity and the resolution on gelatinization (55-65 C), indicating an increase in the carbon chain mobility. The 17O NMR spectra showed a relaxation time (Tx) and sharply decreased in this gelatinization temperature range, indicating an increase in "trapped" water; the correlation time indicated that the D2O mobility was too high to be considered "bound." Added soluted reduced the 170 T2 for water. With added sodium chloride, the 13C spectra were broadened during starch gelatinization (55-95 C), accompanied by a decrease in 23Na T2, indicating a sodium-starch interaction.