Mixing phase behavior of tripalmitin and oleic-rich molecular compound-forming triacylglycerols

Abstract

The binary phase behavior of triacylglycerol (TAG) mixtures constituted by PPP (tripalmitin) and either POP (1,3-dipalmitoyl-2-oleoyl-glycerol), OPO (1,3-dioleoyl-2-palmitoyl-glycerol), or MCPOP/OPO (molecular compound formed by POP/OPO at a 1:1 concentration ratio) was determined by differential scanning calorimetry (DSC), synchrotron (SR-) and laboratory-scale X-ray diffraction (XRD). Steric hindrance due to saturated-unsaturated acyl chain interactions and differences in the thermal stability of TAGs seemed to dictate the independent polymorphic crystallization and transformation observed under kinetic conditions, as well as the very asymmetric eutectic-type phase diagrams obtained from the study of thermodynamically stabilized PPP/POP, PPP/OPO, and PPP/MCPOP/OPO mixtures. Moreover, the solid integration determined for MCPOP/OPO in the βPPP crystalline phase (20-25%), halfway between that of OPO (<5%) and POP (30-35%), showed the ability of molecular compounds to tune the thermophysical properties of fat systems. This highlights the impact that molecular compound-forming TAGs may have on the efficient industrial separation of lipids, and suggest their potential applicability in the development of edible fat blends with tailored functionalities.