An application of magnetic resonance imaging to the real time measurement of the change of moisture profile in a rice grain during boiling

The change of moisture distribution in a rice grain during boiling was observed in real-time by NMR T 2 imaging. A series of one-dimensional proton images along a lateral line (through the cross section) perpendicular to the long axis of the grain was obtained every two minutes using a CPMG multi-spin-echo method. The series of images was analyzed to give the apparent T 2 profile, which was then converted into the moisture content profile. The rise in moisture profile during boiling obtained by real-time observation was found to be unexpectedly rapid when it was compared with that reported previously using a non-real-time method for samples which were quenched after boiling for selected periods of minutes. The error in the NMR imaging method caused by the effect of diffusion on the apparent T 2 was fully analyzed using the pictorial phase diagram method.