Rapid food particle temperature mapping during ohmic heating using FLASH MRI

A fast low angle shoot (FLASH) pulse sequence in combination with a multi-inversion procedure was used to rapidly acquire spin-lattice relaxation data for food particles undergoing ohmic heating. The relaxation data acquired by magnetic resonance imaging (MRI) were analyzed using a two-component exponential model to extract both short and long spin-lattice relaxation time, T₁. The longer T₁ showed a better linear relationship with temperature than the shorter T₁ and, therefore, was used to produce more reliable temperature maps. The MRI temperature maps constructed for ohmically heated food particulates showed an entirely different heating pattern than would be found for similar but conventionally heated particulates and indicated that the temperature inside the particulate could be higher than near the surface of the particulate.