Abstract:

Selective precipitation of αs- and β-caseins from skimmed milk was achieved by the addition of calcium salt at alkaline pH. Effects of final concentration of CaCl2 (adding different volumes of 0.5 mol/L CaCl2 solution to skimmed milk), cooling temperature and repeated dissolution-precipitation procedure times on separation of αs-casein were analyzed by measuring purity of final products using SDS-PAGE followed by Coomassie brilliant blue staining, along with effects of the former two factors on separation of β -casein. The results showed that αs-casein with a purity of 83.33% and β -casein with a purity of 109.53% could obtained when the final concentration of CaCl2 was 0.065 mol/L, the cooling temperature 2 ℃, and the dissolutionprecipitation procedure repeated three times.

Key words: casein, αs-casein, β-casein, separation