Heating skim milk alters the migration of immunoreactive milk proteins in acrylamide gels

Effects of heat treatment on skim milk proteins were characterized using an immunoblot method. Proteins in heat-treated skim milk were separated by polyacrylamide gel electrophoresis (nonreducing and reducing conditions) and electrophoretically transferred to nitrocellulose and β-lactoglobulin, α-lactalbumin, and κ-casein were detected by immunoblotting. High molecular weight immunoreactive β-lactoglobulin was apparent in skim milk samples heated at 65°C and above when electrophoresed under nonreducing conditions. Formation of high molecular weight immunoreactive β-lactoglobulin was observed in heat-treated samples electrophoresed under reducing conditions. Immunoreactive α-lactalbumin in skim milk was not substantially affected by heat treatment. High molecular weigh immunoreactive κ-caesin was present in nonreduced samples from each temperature treatment, including incubation at room temperature, but not in samples electrophoresed under reducing conditions. This immunoblot method should be valuable for further study of intermolecular interactions of milk proteins.