A magnetic resonance study of water uptake in whole barley kernels

The water uptake by barley kernels was followed by 1H NMR spectroscopy. A model was used to explain the first 7 h of imbibition. Measurement of the 1H spin-lattice relaxation rate, R1, showed that during the first 7 h of imbibition, water uptake is dominated by a purely diffusive process with a dependence, where D is the diffusion constant and t is time. While increasing during the first 7 h of imbibition, R1 slowly but continuously decreased afterwards. The observed changes in R1 with imbibition time allowed discrimination between the first two phases in water uptake, as generally observed in germinating seeds. The second phase was characterized by a slow but continuous decrease in R1, indicating a redistribution of water within the kernel. Observed spin-lattice relaxation rates, R1, were treated as a superposition of rates from water molecules in two different physical phases; a mobile and a less mobile phase. Using the Stokes–Einstein–Debye theory for viscosity, the overall water viscosity within the kernel was determined using the two-phase model to describe water mobility.