Isolation of caseins from whey proteins by microfiltration modifying the mineral balance in skim milk

Sodium dodecyl sulfate-PAGE of 2 commercial native casein isolates. Lane 1=β-LG standard; lane 2=β-CN and α-LA standards; lane 3=commercial casein isolate (Micellnor, Kerry Dairy Ingredients, Kerry, Ireland); lane 4=commercial casein isolate (Micellar Casein, American Casein Company, Burlington, NJ); and lane 5=α_S-CN standard.

Calibration curves obtained from SDS-PAGE and using the Scion Image software (Frederick, MD) used to measure the concentration of caseins (α_S-CN and β-CN; solid circles) and whey proteins (α-LA and β-LG; open circles). The solid and dashed lines correspond to the linear regression for the caseins and whey proteins, respectively.

Sodium dodecyl sulfate-PAGE of the UF retentates with the 3 salts tested: A) calcium chloride (CaCl₂), B) sodium phosphate (Na₂HPO₄), and C) potassium citrate (K₃C₆H₅O₇) at 50mM and various initial skim milk sample volume:buffer circulated through the microfiltration system: lane 1=1:5; lane 2=1:10; lane 3=1:15; and lane 4=1:20.

Effect of concentration of calcium chloride (CaCl₂) and volumes of buffer added during microfiltration of skim milk in the concentration of casein from whey protein in the retentate.

Effect of concentration of sodium phosphate (Na₂HPO₄) and volumes of buffer added during microfiltration of skim milk in the concentration of casein from whey protein in the retentate.

Effect of concentration of potassium citrate (K₃C₆H₅O₇) and volumes of buffer added during microfiltration of skim milk in the concentration of casein from whey protein in the retentate.