Magnetic separation technology: Functional group efficiency in the removal of haze-forming proteins from wines

Magnetic nanoparticles were modified by plasma polymerization, using allylamine, acrylic acid and 2-methyl-2-oxazoline as precursor to produce amine, carboxyl and oxazoline functional group rich surfaces. The nanoparticles were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and zeta potential measurements. The capacity of nanoparticles carrying different surface properties to remove haze-forming proteins from Sémillon and Sauvignon Blanc unfined wines was examined by high-performance liquid chromatography (HPLC). The protein capture efficiency of the modified surfaces decreases in the following order: COOH > POx > NH2. This study will help optimising the design of this new technology for the selective removal of haze proteins from white wines.