Ultrafiltration of whey buttermilk to obtain a phospholipid concentrate

Abstract

Concentrates of milk phospholipids (PLs) were extracted from whey buttermilk. The whey buttermilk was centrifuged and deproteinised before ultrafiltration (UF) using peptic or tryptic hydrolysis. UF was carried out using membranes with molecular mass cut-off limits of 30, 50, 100, and 300 kDa. A degree of hydrolysis of >2% was sufficient to separate the whey proteins from the lipids by means of UF. Protein hydrolysis resulted in an increase in PL concentration in the dried powder of about 2.5%. The purity of the PL was enhanced with increasing molecular mass cut-off limits of the UF membranes and with increasing filtration temperatures up to 40 °C. A transmembrane pressure of 1.5–2.0 bar was optimal for both the purity of PLs and the permeation flux. After a four-step diafiltration the final powder contained up to 14.0% PL and the total recovery of PLs after UF and DF was 95–99%.