Capillary flow-MRI of micronized fat crystal dispersions: effect of shear history on microstructure and flow

Micronized fat crystal (MFC) dispersions are a novel food ingredient enabling more efficient manufacturing of fat-based products as compared to established melt-cool processing. Yet, predicting rheological properties of MFC dispersions, remains a challenge. Here, we demonstrate how a capillary-flow Magnetic Resonance Imaging (MRI) platform provides quantitative measurements of local flow of MFC dispersions, inaccessible by global rheology. The measured 2D 1H MRI velocity maps unveiled a 5-fold velocity enhancement, and corresponding increase in wall slip, upon increasing the pre-shear time within 0-5 h, due to the 14% increase in thickness of the crystalline nanoplatelets via recrystallization and aggregation of nanoplatelets. In the absence of pre-shearing, MFC dispersions exhibit an unsheared band at the walls of the capillary, likely arising from fouling and migration of thin nanoplatelets. In contrast to FCDs, flow cooperativity could not be observed for MFC dispersions due to the non-fractality of the fat crystal network. These results demonstrate that, by varying the pre-shear duration, the flow-microstructure properties of the MFC dispersions can be altered in a controlled manner. The approach presented here will allow for rapid assessment of shear-history dependence of flow properties of MFC dispersions under industrially relevant flow conditions.