Mobility of Water in Wheat Flour Suspensions as Studied by Proton and Oxygen-17 Nuclear Magnetic Resonance

The mobility of water in wheat flour suspensions and doughs (30-95% moisture) was investigated by nuclear magnetic resonance (NMR), in water and deuterium oxide. Two frequencies (20, 360 MHz) and two pulse sequences were employed for the proton (¹H) data; the standard 34 MHz and single pulse were used for the oxygen-17 (¹⁷0) NMR data. The standard isotropic two-state model with fast exchange was used to interpret these data by means of the Derbyshire and Kumosinski models. The correlation time for the water “bound” by wheat flour was calculated to be 16.7 ps. The results suggested that the best NMR methodology for the investigation of water mobility in wheat flour suspensions was provided by ¹⁷0 NMR in deuterium oxide. However, both ¹⁷0 and ¹H NMR results showed the same trend in the dependence of the transverse relaxation rate on flour concentration in both water and deuterium oxide.