SEPARATION OF NATIVE CASEIN AND WHEY PROTEINS DURING CROSS-FLOW MICROFILTRATION OF SKIM MILK

Microfiltration of skim milk with 0.1 mu m ceramic membranes was emplo yed for the separation of native casein micelles from the serum protei ns of skim milk. The diafiltered concentrate had a total protein conte nt of over 87% and a casein to total protein ratio of 0.96. When start ing with a low initial flux rate of 62 L/m(2)/h, a volume concentratio n ratio of 3.5 was achieved with a flux decline of only 5% while the t ransmembrane pressure increased from 0.73 to 1.1 bar towards the end o f concentration. Nearly 79% whey protein removal could be achieved und er these conditions. Higher initial flux rates during microfiltration resulted in rapid fouling of the membrane causing high flux declines, increased transmembrane pressure and higher retention of whey proteins . To achieve higher separation of whey proteins, a constant flux and t hereby longer operational runs, the permeate flow rate at the start of microfiltration must be kept low.