Abstract
The polymorphism of 1, 3-rac-stearoyl-arachidoyl-2-oleoylglycerol (SOA) with 98.7% purity prepared from sal fat (sal : Shorea robusta sp.) was determined by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results were compared to 1, 3-rac-palmitoyl-stearoyl-2-oleoylglycerol (POS) with 93.8% purity from cocoa butter. SOA has four polymorphs; the α, γ, β' and β forms, and POS has three polymorphs, the α, β' and β forms. For the α and β' forms of SOA, XRD short spacings identical to those of POS were observed. As to the γ form of SOA, the XRD short spacings were identical to those of 1, 3-dipalmitoyl-2-oleoylglycerol (POP) and 1, 3-distearoyl-2-oleoylglycerol (SOS) in the literature. The XRD short spacing pattern of the β form of SOA was differed somewhat from that of POS. The melting point (43.5°C) of β form of SOA was higher than that (34.7°C) of the β form of POS. The rate of transformation from the metastable β' form to the stable β form in SOA was much smaller compared to POS.
