title: Heat extraction of corn fiber hemicellulose.
abstract: Water-soluble hemicellulose was extracted from corn fiber with microwave-assisted heat treatment. The effects of treatment temperature and initial pH of the aqueous extraction media were investigated regarding hemicellulose recovery and molecular mass of the isolated polysaccharides. In treatments carried out at neutral pH (simple water extraction), it has been demonstrated that hemicellulose recovery could be increased by applying higher treatment temperatures. However, the molecular weight of isolated hemicellulose gets significantly lower. For example, 10% of the raw materials' xylan was extracted at 160 degrees C and about 30% recovery was reached at 210 degrees C. However, the molecular mass of the isolated polysaccharide at 210 degrees C (5.82 x 10(4)) was about half of that measured at 160 degrees C (1.37 x 10(5)). Reducing the pH with sulfuric acid resulted in shorter polymer chains (1.7 x 10(4)) and lower hemicellulose yields (2.2%). Application of sodium hydroxide in the treatment showed that, compared with acid, considerably higher yields (11%) with longer polysaccharide chains (1.3 x 10(5)) could be obtained.
authors.affiliation: Department of Agricultural Chemical Technology, Budapest University of Technology and Economics, Szent Gellérttér 4, H-1521, Budapest, Hungary.
authors.forename: Zsuzsa
authors.initials: Z
authors.lastname: Benko
authors.forename: Alexandra
authors.initials: A
authors.lastname: Andersson
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Szengyel
authors.forename: Melinda
authors.initials: M
authors.lastname: Gáspár
authors.forename: Kati
authors.initials: K
authors.lastname: Réczey
authors.forename: Henrik
authors.initials: H
authors.lastname: Stålbrand
mesh_terms: D006361:Heating / Q000379:methods*; D008872:Microwaves; D011134:Polysaccharides / Q000737:chemistry* / Q000302:isolation & purification* / Q000528:radiation effects; D012972:Sodium Hydroxide / Q000737:chemistry*; D013696:Temperature; D003313:Zea mays / Q000737:chemistry* / Q000528:radiation effects*
chemical_list: D011134:Polysaccharides; D012972:Sodium Hydroxide; C007916:hemicellulose