COMPARISON OF CAPILLARY ELECTROPHORESIS WITH TRADITIONAL METHODS TO ANALYZE BOVINE WHEY PROTEINS

The separation of the four major whey proteins by sodium dodecyl sulph ate (SDS)-capillary gel electrophoresis (CGE) is described. Whilst com mercially purified whey proteins could be analysed using the recommend ed protocol, the more complex nature of an acid whey and a reconstitut ed whey protein concentrate (WPC) powder necessitated considerable ref inement of the CGE sample buffer. Individual whey proteins in the acid whey and WPC samples were then also separated and quantitated using c apillary zone electrophoresis, polyacrylamide gel electrophoresis (PAG E) and HPLC methods and the results were compared. The values obtained for alpha-lactalbumin (alpha-Lac) and beta-lactoglobulin (beta-Lg) we re consistent throughout the various methods, although size-exclusion HPLC, SDS-PAGE and SDS-CGE could not separate the two beta-Lg variants or the glycosylated form of alpha-Lac from the beta-Lg. There was con siderable variation in the values for the bovine serum albumin and imm unoglobulin determined by the different methods and it was concluded t hat none of the methods could satisfactorily quantitate all four whey proteins.