Whey Protein Isolation Overview and Membrane Operations

Fractionation and concentration of whey proteins from whey is one of the more successful industrial applications of ultrafiltration (UF). However, due to flux decline during operation, the practical limit for whey concentration by UF in modern plants is around 24 % total solids, with a protein to total solid ratio limit of ~0.72:1 (Mulvihill and Ennis 2003). Diafiltration is thus employed to achieve a higher protein to total solid ratio, ~0.80:1, with a total solid content of approximately 28 %. However, the efficiency of UF in whey processing is limited by several factors, the most significant of which are concentration polarization and membrane fouling (Rao 2002). Both factors adversely affect permeate flux, which may also be aggravated by protein–protein and membrane–protein interactions (Lipnizki 2005). These impacts however may be minimized by choosing suitable membrane material and configuration as well as the appropriate process conditions such as transmembrane pressure, feed...