The effects of potentially important processing conditions at each step of differential precipitation on the yield and purity of κ-casein fractionated from caprine micellar casein concentrate (MCC) were investigated. The optimal conditions were: rehydrating (3% casein) MCC using homogenisation followed by dissociating micelles at pH 11.0; complexing caseins using 45 mm added Ca at 25 °C for 60 min, followed by precipitating β-/αS-caseins using 2 m acetic acid at pH 7.0 again at 25 °C for 60 min. Two fractionation cycles were used with 50 mm added Ca for the second cycle, followed by precipitating κ-casein at pH 3.8 and 50 °C. To increase processing capacity for scale-up, increased casein concentrations of 4–7% along with 60 mm added Ca resulted in comparable yields and purity of the κ-casein. Maximum yield and purity of 84.6% and 84.4%, respectively, were achieved for κ-casein from the MCC dispersions at 4% casein. <<<

The effects of pasteurisation, high-pressure (HP), and a combination of pasteurisation and high-pressure (PHP) on the physicochemical properties and protein structure of caprine skim milk was investigated. Samples treated by PHP generally had a higher pH, whey protein denaturation, surface hydrophobicity, and intrinsic fluorescence than those treated only with heat or pressure. In contrast, the size of skim milk casein micelles decreased significantly with an increase in pressure level and time; however, the effect was less marked when heat and pressure treatments were combined. For the PHP and HP samples, as the level and time of pressure increased, the α-helix and β-turn content reduced, whereas β-sheet and random coil were induced. Thus, PHP treatment could be used as a good alternative technology in the dairy industry to promote the functional properties of skim caprine milk. <<<