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 systems. With RP, α S2 ‐CN and κ‐CN eluted first as several small peaks; α S1 ‐CN eluted later as two peaks, followed by β‐CN peaks. With AEx, κ‐CN eluted early as a group of peaks, β‐CN eluted next, and α S1 ‐CN and α S2 ‐CN coeluted last. Standard curves were prepared for α S1 ‐CN and β‐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.