Separation of glycosylated caseinomacropeptide at pilot scale using membrane adsorption in direct-capture mode

A direct-capture anion-exchange membrane adsorption process for the separation of a pure glycosylated (gCMP) fraction of caseinomacropeptide (CMP) was successfully developed at pilot plant scale. The method was evolved using a commercial CMP isolate as feedstock as well as fresh sweet whey from skim milk. The former resulted in a binding capacity (BC) of 0.28 mg gCMP/cm2 membrane surface with a purity of 97% while the latter afforded a gCMP fraction with a purity of 91% and a BC of 0.21 mg gCMP/cm2 membrane surface. The main difference was a significant fouling of the membrane adsorber module when the whey was applied, which resulted in a loss of 46% BC after at least five loading/elution cycles. This effect was not observed using the pure CMP isolates and indicates a blocking of the ion-exchange ligands. Triglycerides, as detected by lipid analysis, as well as protein aggregates and casein-flocculates, are mainly responsible for the fouling process. The fouling was decreased using microfiltered whey or by increasing the temperature of the adsorption process. Additionally, a method of repeated elution was shown to decrease the volume of the eluate as well as the NaCl consumption of the elution buffer. The process development further included a desalting and concentration step, which was performed by a 10 kDa ultrafiltration/diafiltration (UF/DF). The efficiency of the UF was strongly influenced by the pH of the solutions and showed best performance at pH 4.1 for the eluate. The residual solution had to be adjusted at pH 6.5 as there was a strong decrease of flux at lower pH levels.