OPTIMIZING CLARIFIED WHEY ULTRAFILTRATION - INFLUENCE OF PH

Whey clarification can be achieved by using a lipid aggregation step f ollowed by microfiltration. The results from using an M5 Carbosep memb rane to ultrafilter defatted sweet whey at pH values in the range 8.0- 1.5 furnished understanding of the fouling process so that fouling may be minimized. The conventional method of aggregation, allowing the pH to decrease naturally, has been compared with a modified aggregation process in which the pH was maintained constant. These two methods dif fered significantly in their influence on the subsequent ultrafiltrati on (UF), with respect to the UF hydraulic characteristics, i.e. revers ible, irreversible and overall fouling resistance. Optimal UF performa nce was obtained at a pH equal to or slightly higher than the aggregat ion pH (7.5) owing to the limited fouling contribution of proteins and calcium phosphates. The modified process permitted UP at fluxes in th e range 50-115 1h(-1) m(-2), with moderate transmembrane pressure, eve n with a protein content two to five times higher than that of regular whey.