Crystallization dynamics in model emulsions from magnetic resonance imaging

Melt crystallization of trilaurin and trimyristin was investigated in the bulk and in dispersed systems using magnetic resonance imaging. Crystallization rates were studied as a function of time in fat/water (40:60) emulsions containing 0.5% tween 80 and 0.2% xanthan gum to prevent creaming. Oil weighted images were obtained to follow the dynamics of crystallization in the bulk and in an emulsified system. Localized spectroscopy using a stimulated echo pulse sequence was used to quantify the crystallization dynamics pattern at different locations in a trimyristin emulsion (40:60). The results showed that crystallization in the emulsified state occurred over a longer period of time than in the bulk. Imaging allowed for the qualitative visualization of crystallization. Images showed crystallization occurring from the edge to the center. On the other hand, localized spectroscopy allowed for spatially quantitative measurement of the amount of liquid oil, crystalline oil and water. In the trimyristin emulsion (40:60), spectra recorded from the top, center and bottom showed a relatively abrupt crystallization pattern starting earlier at the edges of the container, as previously visualized by the images taken.