Abstract
This paper presents the preparation by phase inversion of polysulfone and cellulose acetate ultrafiltration membranes (UF1-UF36) with various amounts of PEG additives (1000, 2000, 4000 Da), designed for the whey protein separation. To establish optimal operating conditions for membrane separation and the membrane with the best characteristics for the ultrafiltration of whey, we determined the flow variation of the two types of whey (pH=6.21, pH=4.35) with different parameters: whey temperature, operating pressure, protein retention and clogging phenomenon. All the results indicated that at the same protein separation efficiency (MWCO), the polysulfone membranes present higher flows than cellulose acetate membranes and their use in the acid whey ultrafiltration process lead to a whey protein concentrate with a protein content about 5 times higher than the initial whey content (6.4 kg/m3). The best protein retention 98.73% was obtained for UF18 membrane (20% PS, 2 % PEG 4000), with optimal flow rate (23.9·10-6 m3/m2s) for acid whey, operating at 50oC and 106 Pa. Keywords: membranes, ultrafiltration, proteins, recovery