Structural Comparison of Arabinoxylans from Two Barley Side-Stream Fractions

Abstract

The structures of barley ( Hordeum vulgare) arabinoxylans isolated from two industrial side fractions, barley husks (BH) and barley fiber (BF), were characterized. Arabinoxylans were extracted with saturated barium hydroxide after enzymatic pretreatment. Barium hydroxide was selective toward arabinoxylans, and only a minor amount of glucose-containing material was coextracted. Acid methanolysis followed by gas chromatography, 1H NMR spectroscopy, and specific enzymatic treatments followed by anion exchange chromatography with pulse amperometric detection (HPAEC-PAD) revealed that the chemical structure of barley husk arabinoxylan (BHAX) clearly differed from that of barley fiber arabinoxylan (BFAX). BFAX was more branched, containing more beta-D-xylopyranosyl (beta-D-Xylp) residues carrying alpha-L-arabinofuranosyl (alpha-L-Araf) units at both O-2 and O-3 positions. BHAX, on the other hand, contained more 2-O-beta-D-Xyl p-alpha-L-Ara f substituents than BFAX. BHAX and BFAX also differed with respect to the hydrodynamic properties investigated with multidetector size exclusion chromatography. BFAX had a higher weight-average molar mass and larger hydrodynamic volume, the latter indicating less dense conformation than BHAX. Mn, Mw /Mn, Rh, and the Mark-Houwink a value were also determined for both arabinoxylans.

Influence of Jet Cooking and pH on Extraction and Molecular Weight of β‐Glucan and Arabinoxylan from Barley (Hordeum vulgare Prowashonupana)

“…The peak molecular weights of arabinoxylans reported in this study were 98,800-125,000. This is lower than previous reports for water-extractable arabinoxylan (177,000-730,000) (Dervilly-Pinel et al 2001;Dervilly et al 2002;Trogh et al 2004), but within the range of alkali-extractable arabinoxylans from barley husk (49,000-81,000) (Pitkanen et al 2008). Molecular weight distribution of extractable arabinoxylans from Prowashonupana barley was not reported previously.…”

“…This is lower than previous reports for water-extractable arabinoxylan (177,000-730,000) (Dervilly-Pinel et al 2001;Dervilly et al 2002;Trogh et al 2004), but within the range of alkali-extractable arabinoxylans from barley husk (49,000-81,000) (Pitkanen et al 2008). This is lower than previous reports for water-extractable arabinoxylan (177,000-730,000) (Dervilly-Pinel et al 2001;Dervilly et al 2002;Trogh et al 2004), but within the range of alkali-extractable arabinoxylans from barley husk (49,000-81,000) (Pitkanen et al 2008).…”

Lignin-rich Enzyme Lignin (LREL), a Cellulase-treated Lignin-Carbohydrate Derived from Plants, Activates Myeloid Dendritic Cells via Toll-like Receptor 4 (TLR4)

“…Thus, we believe that, just like the lignin, the molecular structure of polysaccharides in LREL was similar to that of PEL, and the higher content of neutral sugars in LREL might be contributing to its higher activity. As reported previously, the major types of dietary fiber present in the barley husk were ␤-glucan and arabinoxylan (32,33). Thus, barley husk contained mainly xylose, arabinose, and glucose and only minor amounts of galactose, mannose, and uronic acids.…”

Adsorption of cationized barley husk xylan on kraft pulp fibres: influence of degree of cationization on adsorption characteristics

“…Assignment of the main proton signals was based on 1 H data reported by Höije et al (2006) and Pitkänen et al (2008). The a-L-arabinofuranosyl (a-L-Araf) anomeric proton region at 5.6-5.2 ppm showed two major peaks at 5.54 and 5.39 ppm.…”

“…An example of such a potential residue is barley husks (cf. Glasser et al 2000;Höije et al 2005;Krawczyk et al 2008;Pitkänen et al 2008;Roos et al 2009), a side-stream waste material from the manufacture of starch and ethanol. The main structural features of barley husk xylan were early identified (Aspinall and Ferrier 1957) and further knowledge of the structure was recently obtained by means of NMR (Höije et al 2006).…”