Assessment of water diffusivity in gelatine gel from moisture profiles. I--Non-destructive measurement of 1D moisture profiles during drying from 2D nuclear magnetic resonance images

This first part describes the experiments. A specific assembly adapted to the small microimaging probehead was built to promote isothermal and unidirectional drying of the samples. Successive steps were developed to calculate local moisture contents from independent calibration and sources of error were evaluated. It was shown that 2D NMR signal amplitude images must be recorded to derive the true 1D moisture content profiles although the time acquisition is longer. The time variation of 1D moisture content profiles with a spatial resolution of 49 μm and shrinkage was analysed.