Extraction of glucuronoarabinoxylan from quinoa stalks (chenopodium quinoa willd.) and evaluation of xylooligosaccharides produced by GH10 and GH11 xylanases

Daniel Martin Salas-Veizaga, Rodrigo Villagomez, Javier A. Linares-Pastén, Cristhian Carrasco, María Teresa Álvarez, Patrick Adlercreutz, Eva Nordberg Karlsson

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24 Scopus citations

Abstract

Byproducts from quinoa are not yet well explored sources of hemicellulose or products thereof. In this work, xylan from milled quinoa stalks was retrieved to 66% recovery by akaline extraction using 0.5 M NaOH at 80 °C, followed by ethanol precipitation. The isolated polymer eluted as a single peak in size-exclusion chromatography with a molecular weight of >700 kDa. Analysis by Fourier transform infrared spectroscopy and nuclear magnetic resonance (NMR) combined with acid hydrolysis to monomers showed that the polymer was built of a backbone of ß(1 ? 4)-linked xylose residues that were substituted by 4-Omethylglucuronic acids, arabinose, and galactose in an approximate molar ratio of 114:23:5:1. NMR analysis also indicated the presence of α(1 ? 5)-linked arabinose substituents in dimeric or oligomeric forms. The main xylooligosaccharides (XOs) produced after hydrolysis of the extracted glucuronoarabinoxylan polymer by thermostable glycoside hydrolases (GHs) from families 10 and 11 were xylobiose and xylotriose, followed by peaks of putative substituted XOs. Quantification of the unsubstituted XOs using standards showed that the highest yield from the soluble glucuronoarabinoxylan fraction was 1.26 g/100 g of xylan fraction, only slightly higher than the yield (1.00 g/100 g of xylan fraction) from the insoluble fraction (p < 0.05). No difference in yield was found between reactions in buffer or water (p > 0.05). This study shows that quinoa stalks represent a novel source of glucuronoarabinoxylan, with a substituent structure that allowed for limited production of XOs by GH10 or GH11 enzymes.

Original languageEnglish
Pages (from-to)8663-8673
Number of pages11
JournalJournal of Agricultural and Food Chemistry
Volume65
Issue number39
DOIs
StatePublished - 4 Oct 2017

Bibliographical note

Publisher Copyright:
© 2017 American Chemical Society.

Keywords

  • Bacillus halodurans
  • Endoxylanase
  • Rhodothermus marinus
  • XOs
  • Xylan

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