The thermal decomposition of granular and fluid soybean lecithins

The effect of heat on the decomposition of two grades of soybean lecithin has been examined up to 600°C using differential scanning calorimetry and thermogravimetry. Studies were carried out in both air and argon and a kinetic analysis of the isothermal rates of reaction was attempted. Three principal decomposition stages were distinguished in argon and four in air for a water-dispersible lecithin typical of the quality of the material used in many industrial applications. Gas chromatography showed that the principal gases evolved from 50 to 600°C in argon from the water-dispersible lecithin in contact with aluminum surfaces were C₁-C₆ hydrocarbons, carbon dioxide, carbon monoxide, water and traces of hydrogen.