Comparison of Protein Preparation Procedures and Starch versus Polyacrylamide Gel Electrophoresis for Examining Casein Degradation Products in Cheese

Abstract

Casein degradation products in five varieties of cheese, ranging in age from one day to 13 months, were prepared for zonal electrophoresis in both starch and polyacrylamide gels by oxalate solubilization, hexane extraction, and direct dispersion in alkaline urea buffer.No significant differences were observed in the electrophoretic patterns related to the method of protein preparation, and therefore, the simpler, direct dispersion procedure is recommended. Starch and polyacrylamide gel electrophoresis provided a similar number and location of protein zones for the different cheese varieties although the zones in starch gel electrophoresis were more symmetrical and better defined. Starch gel electrophoresis provided better resolution of the κ-casein region zones than polyacrylamide gel electrophoresis and also permitted simultaneous examination of cationic casein degradation products.