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) perpen dicular to the long axis of the grain was obtained every two minutes u sing 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 mo isture content profile. The rise in moisture profile during boiling ob tained by real-time observation was found to be unexpectedly rapid whe n it was compared with that reported previously using a non-real-time method for samples which were quenched after boiling for selected peri ods of minutes. The error in the NMR imaging method caused by the effe ct of diffusion on the apparent T-2 was fully analyzed using the picto rial phase diagram method. (C) 1997 Elsevier Science Limited.