Abstract
The experimental and theoretical morphology of fat crystals under non-diffusion limited conditions is reviewed. In addition, recent work on the effect of diffusion limited growth is reported. Growth rate versus supersaturation curves of various flat-needle shaped triacylglycerol crystals grown from solution or melt are presented. In most cases these curves exhibit a transition from a non-linear to a linear regime. In the linear regime, the edges and corners of the flat-neeedle shaped crystals are often determined by diffusion. Due to the high anisotropy of fat crystals, the morphologically unstable patterns observed above the transition, appear as non-faceted or faceted dagger-like shapes, depending whether the top faces are kinetically roughened or not. For tripalmitate grown from trioleate, flat faces are still observed above the transition, despite completely linear kinetics. Only at even larger supersaturation these crystal faces become unstable, showing that flat faces can still be obtained under diffusion limited conditions.