ANALYSIS OF BOVINE CASEINS AND PRIMARY HYDROLYSIS PRODUCTS IN CHEESE BY CAPILLARY ZONE ELECTROPHORESIS

Casein fractions from milk and various cheeses as well as isolated cas ein standards were analysed by capillary electrophoresis under acidic conditions. Capillary electrophoresis was performed on a Waters Quanta 4000 apparatus with a hydrophilically coated or an untreated fused-si lica capillary. The four major caseins in an acid precipitate from mil k were well separated. In addition, the various phosphorylation states of the alpha(s1)- and the alpha(s2)-caseins and some genetic variants of beta-casein were separated. The major casein hydrolysis products f ormed in cheese, para-kappa-casein, alpha(s1)-casein-I and gamma-casei ns, were separated from their parent casein and from most other major caseins. The linearity of the method with respect to injection time an d casein concentration was acceptable. With improved repeatability of peak areas the method should be superior to urea-PAGE and an attractiv e alternative to high-pressure liquid chromatography (HPLC) methods fo r following casein proteolysis in dairy products.