Clarification of aqueous corn extracts by tangential flow microfiltration

Abstract

The effectiveness of tangential flow microfiltration for the solid/liquid clarification of aqueous corn endosperm and germ extracts was examined using recombinant type I human collagen (rCollagen) and green fluorescent protein (GFP) as model proteins. We identified the effects of transmembrane pressure (TMP), crossflow rate, protein molecular weight, and membrane chemistry on permeate flux, protein rejection, and internal membrane fouling in microfiltration. In dead-end filtrations, both endosperm and germ extracts formed highly compressible cakes that provided the dominant hydraulic resistance. For tangential flow filtration using a ceramic membrane, increasing the crossflow rate had a significant beneficial effect on the permeate flux for all TMPs examined. High fouling of the ceramic membrane occurred during the filtration and this was likely due to the presence of soluble corn starch in the feed. Filtration with a ceramic membrane resulted in low rejection (<10%) of both the host cell proteins (HCP) and GFP and very high rejection (∼90%) of rCollagen. In contrast to the ceramic membrane, tangential flow filtration using a poly(vinylidene fluoride) membrane resulted in much less internal fouling and no measurable rejection of HCP, GFP, or rCollagen. Microfiltration was an effective method for the solid/liquid clarification of corn protein extracts, except in cases where high internal membrane fouling resulted in increased rejection of large molecular weight proteins.