Phase equilibria in the system soybean lecithin/water

Abstract

The binary phase diagram of a system of a commercially available purified soybean lecithin and water was determined by X-ray diffraction and polarization microscopy studies. A lamellar liquid crystalline phase exists at room temperature in a region between 35 and 7% (w) of water and this is transformed into an L2-phase at 240 °C. At low water contents there occur at room temperature several crystalline and liquid crystalline structures, which transform above 55 °C into a cubic liquid crystalline structure. This phase exists up to about 130 °C and may contain at most about 15% (w) of water. At still higher temperatures there is a transition into a liquid crystalline hexagonal structure which in turn is transformed into the L2-phase above 240 °C.