QUALITATIVE AND QUANTITATIVE-DETERMINATION OF CASEINS WITH REVERSE-PHASE AND ANION-EXCHANGE HPLC

Whole native caseinate (WNC) and casein (CN) fractions from preparative DE-52 cellulose urea columns were chromatographed using C-8 reverse-phase (RP) and DEAE-type anion-exchange (AEx) HPLC system. With RP, alpha-s2-CN and kappa-CN eluted first as several small peaks; alpha-s1-CN eluted later as two peaks, followed by beta-CN peaks. With AEx, kappa-CN eluted early as a group of peaks, beta-CN eluted next, and alpha-s1-CN and alpha-s2-CN coeluted last. Standard curves were prepared for alpha-s1-CN and beta-CN using RP-PHLC and showed correlation coefficients of 0.99 and 0.98, respectively. The caseins in WNC, nonfat dry milk casein, commercial casein(ates) and caseins from milks of individual cows were determined.