Modification of surface charges of soy protein by phospholipids

Lecithin is used to prevent soy protein isolates from clumping in food processing. A PenKem Inc. System 3000 Electrokinetic Analyzer was used to investigate how the phospholipid modified the surface charge of soy protein. Electrophoretic mobility‐pH curves showed that a commercial soy lecithin lowered the isoelectric point (pI) and increased the electrical mobility of soy protein more than did a pure phosphatidylcholine. The modification of the surface charge of the protein was a function of the phospholipid added. Lecithinated soy isolate was more negatively charged and thus more dispersible in water than the nonlecithinated soy control.