MINIMIZING WHEY-PROTEIN RETENTION IN CROSS-FLOW MICROFILTRATION OF SKIM MILK

The feasibility of fractionating casein and whey protein in skim milk was studied by measuring the permeation of whey protein in a laborator y microfiltration set-up in relation to temperature, circulation veloc ity, transmembrane pressure (TMP) and permeate flux. A tubular, cerami c membrane from Tech-Sep with a nominal pore size of 0.14 mu m was use d. 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 degrees C. For lower circulation velocities and at 15 degrees C, th e protein content decreased when the TMP was increased. For every circ ulation velocity, a lowest value of the TMP corresponding to a limitin g flux was found. The value of the limiting flux increased with increa sing temperature and circulation velocity. The highest value for the l imiting flux was 145 L h(-1) m(-2) for the circulation velocity 8 m s( -1) at 55 degrees C. All results could be roughly correlated as limiti ng flux = 0.0025 Re. (C) 1997 Elsevier Science Ltd.