Study of ultrafiltration of defatted whey protein concentrates (WPC) withdrawn from an industrial plant

Abstract

This study deals with the ultrafiltration (UF) of defatted c1arified whey protein concentrates (WPC) using inorganic MS Carbosep membranes. Based on a prior knowledge of operating conditions and performance of an industrial 4-stage UF plant (150 m2), an experimental laboratbry study was carried out using a monotube rig (2.26 x 10-2 m2) and feed withdrawn from the industrial plant. Flux (J) versus transmembrane pressure (TP) has shown that membrane permeability is significantly improved after defatting clarification (thermocalcic treatment followed by microfiltration). Moreover, no marked limiting fluxes were noted, particularly over a sufficient tangential flow-rate (4.5 or 5.5 m.s-1), so that the membrane could operate at higher fluxes. UF at fluxes equal to those performed by the equipment have confirmed the forecast. Four fouling regimes have been found, which depend on flux, protein concentration, tangential flow rate and the nature of the fouling components (protein adsorption; insoluble salt precipitates on and in the membrane). Reversible phenomena are the major contributors to pressure increase at constant flux but irreversible fouling, Rif, and its alteration rate determine either the stability of UF operating conditions or their divergence which result in an increasingly rapid TP. ultrafiltration