The CLSM was found to be a good technique for monitor the cocoa butter crystallisation in chocolate model systems during cooling. Seeded samples formed multiple nucleation sites, which induced a rapid growth of crystals and resulted in a more homogenous microstructure. The non-seeded samples showed a more random structure, with some areas developing large spherical crystals while other parts gained a more heterogeneous microstructure with large inclusions of liquid fat and small compact crystals. The structure density in the various model systems during storage could be quantified by smallmolecule diffusion at different length scales using FRAP and HPLC. FRAP measurements gave detailed information on the heterogeneity or homogeneity of microstructure in the cocoa butter, whereas the HPLC indicated the impact of solid particles. Both techniques showed significant differences in terms of structure density between the pre-crystallisation processes, seeded and non-seeded. During storage, the non-seeded samples experienced extensive post-crystallisation and evolved towards the dense structure found in the seeded samples. However, the initial less compact structure in the non-seeded samples created a more favourable environment in which the global diffusion could occur.
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