Characterization of Milk Proteins in Ultrafiltration Permeate

Pasteurized, unhomogenized whole milk was ultrafiltered with a Dorr-Oliver, Series S, plate and frame pilot unit containing seven commercial S-10 polysulfone membranes with a 10,000 molecular weight cut-off. Permeate was collected and protein was isolated from the permeate. Proteins precipitated from the UF permeate by 12.5% TCA were weighed and then characterized by SDS-PAGE. Only a very small amount of protein (.25 g/l) was present in the permeate and approximately 90% of that protein was α-lactalbumin.