EFFECT OF SORBITAN TRISTEARATE ON THE THERMAL AND STRUCTURAL-PROPERTIES OF MONOACID TRIGLYCERIDES - INFLUENCE OF A CIS OR TRANS DOUBLE-BOND

The influence of sorbitan tristearate (STS) on the thermal and structural properties of monoacid triglycerides, tristearin (SSS), trielaidin (EEE) and triolein (OOO), has been studied by differential scanning calorimetry and powder X-ray diffraction at variable temperature. Results coming from the polymorphic study show that, following a dynamic process, the effect of 5% in weight of STS on the crystalline transitions depends on the thermal behaviour of the triglycerides and more precisely on the alpha --> beta' transformation way, i.e. solid state or melt-mediated. The intersolubility between the triglycerides and STS has been determined from ''temperature versus composition'' binary phase diagrams. In each case, the interaction is of eutectic type. STS is partially miscible into the considered triglyceridic lattices; a maximal solubility is reached into SSS, whereas OOO incorporates only small amounts of the emulsifier.