Acylation and solubility of casein precipitated by carbon dioxide

Casein precipitated from milk using carbon dioxide (CO2-casein) and calcium caseinate were acetylated and succinylated. Aqueous solubility of casein was measured at pH 3, 5, 7, and 9, Acetylation extent was lower for CO2-casein while both succinylated to similar extents, Solubility between the unmodified caseins was similar except at pH 5 with CO2-casein being less soluble. Succinylation enhanced solubility for both caseins at pH 5, 7, and 9 with similar solubility between the succinylated caseins at each pH. Acetylation enhanced solubility at pH 5, however CO2-casein still possessed lower solubility than calcium caseinate. Acylation and solubility behavior indicated structural features in CO2-casein which were not present in calcium caseinate.