Effect of Heat on the Proteins of Milk as Revealed by Gel and Immunoelectrophoresis

Abstract

The milk proteins (serum albumin, [beta]-lactoglobulin, casein and immune globulin) were separated by gel electrophoresis. They were further defined by immunoelectrophoresis, a combination of gel electrophoresis and antigen-antibody precipitation. The 4 electrophoretic fractions and [alpha]-lactalbumin formed precipitation arcs when reacted with their antisera. [beta]-Lactoglobulin and [alpha]-lactalbumin had weak antibody stimulating properties. Casein existed as a homogeneous substance. A complex existed between [beta]-lactoglobulin and casein in raw skimmilk. Effect of heat on stability in increasing order was immune globulin, [alpha]-lactalbumin, serum albumin, [beta]-lactoglobulin and casein. Immunoelectrophoretic patterns of acid precipitated casein reacted against various antisera showed a complex between [beta]-lactoglobulin and casein, and between casein and serum albumin.