Evolution of Fat Crystal Network Microstructure Followed by NMR

Model systems composed of tristearin in solid state and tricaprin in liquid state with different solid-fat content (SFC) and storage time have been investigated by relaxation NMR and NMR diffusometry. The T-2 relaxation of the tricaprin in the melt exhibited a bimodal distribution as previously observed. The SFC had a major effect on the T-2 relaxation. This effect was explained according to the fast diffusive exchange model in porous media. According to this model the changes in T-2 relaxation as a function of the SFC and storage time were explained by the decrease of the surface-to-volume ratio of the crystal induced by Ostwald ripening. The diffusion coefficient D of the tricaprin in the melt decreased for higher SFC. Since no significant variation of D was observed for different diffusion time, D reflected the long-range connectivity and the tortuosity was calculated. During storage the diffusion coefficient remained constant.