title: Comparison of anion-exchange and hydroxyapatite displacement chromatography for the isolation of whey proteins.
abstract: In displacement chromatography, several substances may be isolated and concomitantly concentrated, which makes this separation procedure attractive for the processing of diluted product streams containing a number of high value substances. Here, the suitability of anion-exchange and hydroxyapatite displacement chromatography for the processing of technical dairy whey is investigated. The pH and flow-rate of the carrier, the displacer chemistry and, in case of the apatite, the particle diameter of the stationary phase are considered. As a consequence of the pH sensitivity of the beta-lactoglobulin, one major whey component, apatite displacement chromatography is less then successful in whey separation. At a denaturing carrier pH (> 8.5) the beta-lactoglobulin zone is broad and stretches over the entire displacement train. At a lower carrier pH, previously successful polyanionic displacers do not bring about separation, while low-molecular-mass ones do, but they tend to overrun and thus contaminate the protein zones. In the case of anion-exchange displacement chromatography, polyanions, especially polyacrylic acid (PAA, M(r) 6000), constitute suitable displacers. Here too, a carrier pH of 8.0 is most suited to the separation of the whey proteins. The low-molecular mass-displacer iminodiacetic acid (IDA, M(r) 133.4), on the other hand, displaces only alpha-lactalbumin. The beta-lactoglobulin remains on the column. PAA is used as the displacer to process a dairy whey sample.
authors.affiliation: Laboratoire de Biotechnologie Cellulaire et Moléculaire, Institute de Génie Chimique, ETH Lausanne, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Vogt
authors.forename: R
authors.initials: R
authors.lastname: Freitag
mesh_terms: D000818:Animals; D000837:Anion Exchange Resins / Q000737:chemistry*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D006882:Hydroxyapatites / Q000737:chemistry*; D007768:Lactalbumin / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D007782:Lactoglobulins / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D008863:Microspheres; D008894:Milk Proteins / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*; D010316:Particle Size; D011506:Proteins / Q000032:analysis; D000067816:Whey Proteins
chemical_list: D000837:Anion Exchange Resins; D006882:Hydroxyapatites; D007782:Lactoglobulins; D008894:Milk Proteins; D011506:Proteins; D000067816:Whey Proteins; D007768:Lactalbumin