Extraction and Separation of alpha-lactalbumin and beta-Lactoglobulin from Skim Milk by Microfiltration and Ultrafiltration at High Shear Rates: A Feasibility Study

This paper presents a two-stage membrane filtration process for extracting and separating -Lactalbumin (-La) and -Lactoglobulin (-Lg), from UHT skim milk, using dynamic filtration. The 1st stage separates casein micelles in retentate from whey proteins in the permeate with rotating 0.2 mu m pores ceramic membrane disks. Casein micelles rejection was excellent, while -La and -Lg transmissions remained between 80 and 90%. The permeate flux at 40 degrees C ranged from 105 to 40Lh-1m-2 at a volume reduction ratio of VRR=4. The 2nd stage consisted of ultrafiltration of the previous permeate with a metal disk rotating at 2000rpm near a fixed 50kDa PES membrane, in order to concentrate -Lg in retentate, while collecting -La in the permeate. The flux dropped from 270Lh-1m-2 at VRR=1, and remained nearly constant at 200Lh-1m-2 until a VRR of 3.3. -La transmission increased with VRR to reach 23% at VRR=3.3, while -Lg transmission decayed at increasing VRR to 3%, to give a maximum selectivity of 8.