Initial pasteurisation effects on the protein fractionation of skimmed milk by microfiltration

Microfiltration using 0.1–0.2 μm membranes enables protein fractionation of skimmed milk into a casein-rich fraction and a permeate that contains native whey proteins. High-temperature, short-time pasteurisation is often one of the first treatments in many dairy processes. The objective of this study was to investigate whether initial pasteurisation would affect the fractions that are obtained from the one-stage microfiltration of skimmed milk. Pasteurised and unpasteurised skimmed milk were fractionated at 55–58 °C using 0.2 μm ceramic membranes. Chemical analysis of the microfiltration fractions showed that both the nitrogen and mineral distributions were altered by the initial pasteurisation. The permeate that was obtained from microfiltration of the unpasteurised milk contained higher amounts of calcium, phosphorous and native whey proteins, in addition to a lower amount of casein fragments passing through the membrane. The retentate that was obtained from microfiltration of the unpasteurised milk contained less total protein and casein.