The density of liquid and polymorphic crystalline forms of 2-oleoyl-1, 3-dipalmitoylglycerol (POP), 2-oleoyl-1, 3-rac-palmitoyl-stearoylglycerol (POS), and 2-oleoyl-1, 3- distearoylglycerol (SOS) were measured by gas pycnometer. An 0.18 nm3 decrease in molecular volume was observed in all triacylglycerols, corresponding to structural changes in the most stable form of β1 of the three triacylglycerols. More precisely, the saturated and unsaturated fatty acyl moieties in the triacylglycerols showed no monotonous change in volume. In sample preparation, density of each polymorphic forms was observed to be highest by symple melt cooling. For melt mediated transformation, and solid state transformation, the values of this parameter were less.
Calorific values of glyceryl monopalmitate (GMP) during crystallization from ethanol solution containing sorbitan laurate (SL) were determined with a differential scanning calorimeter (DSC). Molecular interactions between GMP and SL in erthanol are discussed. This parameter was taken as the enthalpy change (ΔH) in GMP crystallization. ΔH of GMP crystallization from 0.2 mol/kg of GMP in the absence and presence of SL (0.38 mol/kg) in ethanol was 74 and 62 kJ/mol, respectively. Crystallization temperature in the latter case decreased by about 9°C. The same conditions the apparent activation energy of GMP crystallization was determined from Avrami-Erofe'ev equation. It was found to decreased with increase in SL concentration in GMP solution in ethanol. This consistent with crystallization GMP from ethanol. The results are discussed in relation to findings presented in the previous paper.