Magnetic solid-phase extraction: A nanotechnological strategy for cheese whey protein recovery

Abstract

In this contribution, magnetite nanoparticles coated with citric acid and Cu2+ ions in different proportions were employed as adsorbents for removing proteins from cheese whey. Characterization included FTIR, Zeta potential measurements, hydrodynamic diameter determination and microscopy. Protein concentration in whey was reduced between 14 and 60% depending on the composition of the magnetic adsorbent. The protein-loaded particles were isolated by magnetic decantation and washed with NaCl to achieve protein desorption. 53% of adsorbed proteins could be recovered from Cu/citric acid/magnetite whereas only 24% was recovered from citric acid-magnetite using 2 M NaCl as eluent. Electrophoresis analysis revealed that the main protein in NaCl washing was β-lactoglobulin. Proteins were mostly covalently crosslinked onto citric acid/magnetite, while ionic interactions governed linking of proteins onto Cu/citric acid/magnetite, considering easiness of elution with NaCl. The materials herein developed emerge as an interesting alternative for both whey protein purification and β-lactoglobulin recovery.