SYNTHESIS AND PHYSICOCHEMICAL CHARACTERIZATION OF MIXED DIACID TRIGLYCERIDES THAT CONTAIN ELAIDIC ACID

The synthesis of symmetrical and asymmetrical palmito- and stearo-elai dic triglycerides (PEP, SES, EPP, PEE, ESS, and SEE, in which P = palm itic, S = stearic, and E = elaidic acid) was undertaken to investigate their polymorphism. The chemical pathways and the purification steps, including crystallization and adsorption chromatography, are describe d. The different chromatographic analyses (gas-liquid chromatography: carbon number profile and fatty acid methyl ester profile, and high-pe rformance liquid chromatography) revealed that the purity of the synth esized products was superior to 99% except for SES (>96%). The thermal behavior, as well as the polymorphism of these triglycerides, has bee n investigated by means of differential scanning calorimetry and powde r X-ray diffraction spectroscopy at variable temperatures. The six com pounds crystallize according to a double chainlength packing. The most stable polymorphic form of palmito-elaidic triglycerides belongs to t he beta' variety, whereas the stearo-elaidic triglycerides are beta st able.