Distinction between glycomacropeptide and β-lactoglobulin with 'stains all' dye on tricine SDS-PAGE gels

Identification of glycomacropeptide (GMP) and β-lactoglobulin (β-lg) present in cheese whey is difficult on SDS-PAGE due to their close proximity during electrophoresis and poor sensitivity of commonly used staining dye 'coomassie brilliant blue' (CBB) towards GMP. A simple method has been developed for the detection of GMP and β-lg by staining acrylamide gel after tricine SDS-PAGE using cationic 'stains all' dye. After staining and destaining major whey proteins, viz. ɑ-lactalbumin (ɑ-la) and β-lg appear red while GMP stains blue. The method can be used for the identification of these macromolecules in cheese whey and the detection of adulteration of milk with rennet whey.