SEPARATION AND QUANTIFICATION OF BOVINE-MILK PROTEINS BY REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Current analytical methods for milk proteins lack the capacity to simu ltaneously separate and quantify the six major bovine milk proteins an d their genetic variants. A method is described that simultaneously se parates and quantifies the six major bovine milk proteins. The separat ion is based on reversed-phase partitioning of the six major milk prot eins and several genetic variants of ic-casein, beta-casein, and beta- lactoglobulin. The described method has for each of the six milk prote ins a linear quantitative response, precision (coefficient of variatio n below 5.1% within days of analysis, and below 7.1% between days of a nalysis), resolution (over 2.5 between proteins), peak efficiency (the oretical plate numbers between 8 000 and 50 000), and a sample treatme nt without filtration steps that together with the analysis takes 2 h. The composition of protein from milk of each of 234 cows was determin ed using the current method, and the results were similar to reference values for milk proteins.