Minimizing whey protein retention in cross-flow microfiltration of skim milk

Abstract

The feasibility of fractionating casein and whey protein in skim milk was studied by measuring the permeation of whey protein in a laboratory microfiltration set-up in relation to temperature, circulation velocity, transmembrane pressure (TMP) and permeate flux. A tubular, ceramic membrane from Tech-Sep with a nominal pore size of 0.14 μm was used. The protein content in the permeate was found to be independent of TMP up to 190 kPa for the highest circulation velocity, 8 m s−1, at 55 °C. For lower circulation velocities and at 15 °C, the protein content decreased when the TMP was increased. For every circulation velocity, a lowest value of the TMP corresponding to a limiting flux was found. The value of the limiting flux increased with increasing temperature and circulation velocity. The highest value for the limiting flux was 145 L h−1 m−2 for the circulation velocity 8 m s−1 at 55 °C. All results could be roughly correlated as limiting flux = 0.0025 Re.