Triacylglycerol crystal growth: templating effects of partial glycerols studied with synchrotron radiation microbeam X-ray diffraction

Microstructural investigation of palm oil (PO) containing 8% monopalmitin (MP) was performed using synchrotron radiation microbeam (beam area of 5 x 5 mu m(2)) X-ray diffraction (SR-mu-XRD). The blend was isothermally crystallized at 20 degrees C and analyzed shortly after reaching the crystallization temperature and after aging at 20 degrees C. The SR-mu-XRD technique allowed demonstration of the templated effect of the monoacylglycerol (MAG) by showing that the PO crystals were orientated by the previously crystallized MP. Interactions through the palmitic acid moiety in PO and MP must have played decisive roles in this template effect as revealed that the MP crystals migrate and concentrate into large spherulitic crystals during long-term storage, probably caused by a process of Ostwald ripening