The use of a ceramic microfiltration (MF) membrane for the fractionation of buttermilk and whey buttermilk obtained from pilot scale churning of cream and whey cream from industrial sources has been studied. Whey buttermilk contained comparable amounts of phospholipids compared to regular buttermilk but its protein content was lower due to the absence of caseins. However, it was found that lipid content of whey cream did vary significantly between lots resulting in important variations in the fat content of whey buttermilk. A twofold MF concentration of regular buttermilk doubled its phospholipids content whereas that of whey buttermilk was increased by 50%. The overall efficiency of the MF processing of regular buttermilk was limited by the amount of caseins retained by the MF membrane. Analysis of the protein profile of permeates and retentates showed that the transmission of milk fat globule membrane proteins by the MF membrane was lower when using whey buttermilk as compared to regular buttermilk possibly indicating the influence of casein micelles in fractionation or some structural differences between both products. (c) 2005 Elsevier Ltd. All rights reserved.