Ceramic membrane filtration of skim milk for the production of a casein-enriched permeate

The protein composition of skim milk was adjusted using a pilot-scale membrane microfiltration system to produce a casein-enriched permeate with a ratio of casein to serum protein close to 1:1. Microfiltration was performed at 50 °C to a volume concentration factor of 3 followed by 2 diafiltration steps. Three different membrane pore sizes (0.10, 0.14 and 0.20 μm) were used to compare the separation effect, then the effect of three different transmembrane pressures (100, 120 and 150 kPa) on protein composition in the permeate was studied. Membranes of 0.10 and 0.14 μm retained most of the casein. The 0.20 μm membrane allowed casein to pass through and made the ratio of casein to serum protein in the permeate close to 50:50 with a mean flux of 128.3 kg m−2 h−1 at 120 kPa, demonstrating the potential application of a 0.20 μm membrane to produce a new dairy ingredient.