Isolation and characterization of physicochemical and material properties of arabinoxylans from barley husks

Different methods of isolating arabinoxylans from barley husks were compared and the effect of isolation method on yield, composition and physicochemical as well as material properties was investigated. The isolation involved HCl or enzyme pretreatment, chlorite or organosolv delignification and an extraction with aqueous alkali. Four fractions of isolated arabinoxylan were obtained. The arabinoxylan content in the isolated fractions varied between 50 and 83%, with the highest content in the chlorite-delignified sample. In addition to the sugar composition, the amount of lignin and protein was determined. The molecular weights of these samples varied between 35,000 and 45,000 g/mol, determined by SEC in water and DMSO. Films were made by water casting, and the delignified samples formed clear and flexible films. The mechanical properties of the chlorite-delignified films were evaluated by tensile testing. The stress at break was 50 MPa and strain at break 2.5%. Measurement of the equilibrium moisture content at 50% RH and 100% RH showed that the films were highly hygroscopic. (C) 2005 Elsevier Ltd. All rights reserved.