Suitability of commercial caseinates in comparison to micellar casein as raw material for isolation of food-grade β-casein

Commercial caseinates (CT) and micellar caseins (MCN) were screened as potential sources for isolation of food-grade β-casein by means of selective precipitation. The reconstituted micellar casein and caseinates were alkalized to pH 11 and as- and β-casein precipitated by calcium chloride. The resuspended precipitate was held at 2 °C for 120 min, allowing β-casein to dissociate into the aqueous phase. β-casein was precipitated from the supernatant and freeze-dried. The mean purities of the isolated β-casein fractions (P β-CN ) were between 91 and 96%. No significant purity differences were observed between the fractions derived from micellar caseins and commercial caseinates. β-casein yield (Y * β-CN ) and recovery (R β-CN ) were significantly lower in the commercial caseinate group. The β-casein yield of the fractions derived from micellar casein ranged from 9 to 11 % (20% ≤ R β-CN ≤ 24 %) and from commercial caseinates from 2 to 3% (3% ≤ R β-CN ≤ 5%). Within the caseinate group, neither the drying process (extrusion, roller, spray drying), nor the type of caseinate (NaCT, CaCT, KCT) had a significant influence on β-casein purity, yield, or recovery.