title: Hydroxyl radical oxidation of feruloylated arabinoxylan.
abstract: Feruloylated arabinoxylan (AX) has a unique capacity to form covalent gels in the presence of certain oxidizing agents. The present study demonstrates that hydroxyl radical oxidation does not provoke ferulic acid dimerization and thus oxidative gelation. We studied the hydroxyl radical mediated oxidation of an alkali-extracted AX preparation (purity: 92g/100g dry matter) that showed gel-forming capability upon peroxidase/hydrogen peroxide treatment. Hydroxyl radicals were produced with ascorbate-driven Fenton reaction and the radical formation was monitored with electron paramagnetic resonance, using a POBN/EtOH spin trapping system. Oxidation was carried out at different catalytic concentrations of iron (50 and 100μM) and at different temperatures (20°C, 50°C, and 80°C). It was demonstrated that hydroxyl radical oxidation does not provoke gel formation, but viscosity decrease in AX solution, which suggests polymer degradation. Furthermore, it was demonstrated that hydroxyl radical formation in AX solution can be initiated merely by increasing temperature.
authors: Institute of Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 9, CH-8092 Zurich, Switzerland; Department of Applied Biochemistry and Food Science, Budapest University of Technology and Economics (BME), Műegyetem rkp. 3, H-1111 Budapest, Hungary. Electronic address: bagdiattila@mail.bme.hu.
authors: Attila
authors: A
authors: Bagdi
authors: Department of Applied Biochemistry and Food Science, Budapest University of Technology and Economics (BME), Műegyetem rkp. 3, H-1111 Budapest, Hungary. Electronic address: tomoskozi@mail.bme.hu.
authors: Sándor
authors: S
authors: Tömösközi
authors: Institute of Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 9, CH-8092 Zurich, Switzerland. Electronic address: laura.nystroem@hest.ethz.ch.
authors: Laura
authors: L
authors: Nyström
mesh_terms: D003373:Coumaric Acids / Q000737:chemistry* / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D017665:Hydroxyl Radical / Q000737:chemistry / Q000378:metabolism*; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D013696:Temperature; D014990:Xylans / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D003373:Coumaric Acids; D016877:Oxidants; D014990:Xylans; D017665:Hydroxyl Radical; C085118:arabinoxylan; C004999:ferulic acid
keywords: Arabinoxylan; EPR; Gelation; Hydroxyl radical; Oxidation; Viscosity