Crystallisation of triacylglycerols in nanoparticles

The crystallisation properties of a mixture of triacylglycerols (TG), cocoa butter (CB) 75%/miglyol 25%, were investigated on cooling at 0.5 A degrees C/min using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The influence of (i) the dispersion of TG within nanoparticles stabilised by proteins, and of (ii) the presence of polar lipids were characterised. In bulk, crystallisation of TG successively occurred with a alpha 2L (49.3 ) structure, then the formation of longitudinal stackings of 44.5 and 34.5 of beta' form was interpreted as co-crystallisation of TG from CB and miglyol. The dispersion of TG in nanoparticles of about 400 nm induced a higher supercooling and changed their crystallisation properties. The formation of alpha 49.2 and beta' 45 structures corresponded to the segregation of TG from CB in solid phases while TG from miglyol remained liquid. Phospholipids with saturated fatty acid chains affected the thermal properties of TG, which demonstrated their localisation at the surface of the nanoparticles. DSC and XRD revealed to be very sensitive and adapted methods to increase the knowledge about the mechanisms of crystallisation in emulsion.