Influence of triglyceride composition on crystallization kinetics of model emulsions

Abstract

Melt crystallization of trimyristin was investigated in colloidal systems, using magnetic resonance imaging (MRI) and differential scanning calorimetry (DSC). Alterations in crystallization behavior were produced by adding various percentages of trilaurin to the emulsion. Crystallization rates were studied as a function of time in fat/water emulsions (40:60, v/v) containing 0·5% Tween 80 and 0·2% xanthan gum to prevent creaming. Using MRI, oil weighted images followed crystallization in the trimyristin emulsions containing 0, 10 and 20% (volume per oil phase volume) of trilaurin, respectively. Localized spectroscopy, using a stimulated echo sequence, was used to determine the crystallization at different locations in (40:60) trimyristin emulsion samples. The addition of trilaurin to the trimyristin emulsion changed the crystallization pattern. Spectra recorded from the top, center and bottom showed a relatively abrupt crystallization pattern in the (40:60) trimyristin emulsion, whereas the trilaurin containing emulsions exhibited a longer time frame for crystallization. Phase behavior was also assessed using DSC. Nucleation and subsequent crystallization in bulk or within the droplets in the emulsions were detected by isothermal heat evolution. The isothermal DSC results paralleled results obtained with MRI. The results suggested that the crystallization pattern was altered as a function of the triglyceride composition of the oil phase.