Real-time mapping of moisture migration in cereal based food systems with Aw contrast by means of MRI

The redistribution of water in prototype food systems, comprising phases with contrasting water activity (Aw), was investigated. To accomplish this task, MRI techniques adapted to migration rate were used. RARE and SPI measuring methods were used to monitor water redistribution in crunchy inclusions in water and biscuit shells with apple filling during storage, respectively. In the first case, fast migration, which typically last some tens of minutes, was monitored with a temporal resolution 3.5 min or better, while in the second case of slow migration it was monitored during 2 months with 10 days temporal resolution. 3D MR images with sub-millimeter resolution visualise the spatial redistribution of moisture and allow a quantification of its rate and extent of matrix swelling. Correlation with high resolution X-ray (XRT) images allows to identify structural elements responsible for unwanted fast hydration. The obtained results demonstrate the potential of a combined MRI/XRT approach for dynamical monitoring of the migration of moisture into porous cereal material in a broad range of Aw contrast and hydration levels. The measured migration rates through samples of different internal structures can be used for validating models for prediction of water redistribution in multiple phase systems in a quantitative manner