RHEOLOGICAL CHARACTERIZATION OF SOYBEAN LECITHIN IN MIXTURES OF DEGUMMED OIL AND FATTY ACIDS

One of the operations realized during the production of lecithin is the standardization, which is made by the addition of oil and fatty acid. This study aimed to realize the rheological characterization of the dispersions of soybean lecithin, degummed soybean oil, and fatty acids. The flow curves showed that all dispersions were pseudoplastic fluids, time-dependent viscous flow with thixotropic behavior. Ostwald-De-Weale model fitted properly the shear stress and shear rate data, with values of rheological index and consistency coefficient in the range of 0.73 – 0.97 and 1.02 – 28.32 Pa.sn, respectively. The increase in degummed oil content weakened the pseudoplastic behavior of lecithin formulations. The percentages of thixotropy of lecithin and mixtures ranged from 5.3 to 54.4%, and the addition of degummed oil and fatty acid reduced the thixotropic behavior of crude soybean lecithin. As for color, there were no significant differences between dispersions, with values around 5.0 measured on the Gardner scale.