1 research outputs found
Investigation of Xylose Reversion Reactions That Can Occur during Dilute Acid Pretreatment
Xylose
reversion reactions to form xylooligomers represent a potentially
important mechanism of sugar loss during dilute acid pretreatment
of biomass. We have conducted a study to identify the products that
result from these reactions and to determine the kinetics of their
formation. A major obstacle is that there are few commercial standards
available for xylose disaccharides, which are essential for the identification
and quantification of the xylose reversion products formed during
these reactions. To overcome this obstacle, we have used GC/MS and
NMR analysis of xylose disaccharides isolated by preparative HPLC
to identify the reaction products. At the xylose concentration we
used (300 g L<sup>–1</sup>), only xylose disaccharides were
observed. As with glucose reversion reactions [Pilath, H. M.; et al. <i>J. Agric. Food Chem</i>. <b>2010</b>, <i>58</i>, 6131], the disaccharides contained linkages that involved the anomeric
carbon atom of one of the sugar monomers. Eight out of the nine possible
disaccharides, including alpha and beta anomers, were observed. Whereas
the GC/MS allowed for the identification of the linkages, NMR was
needed to distinguish between the α and β isomers of the
disaccharides. The kinetics of combined xylose disaccharide formation
was measured using HPLC. Arrhenius parameters for the rates of disaccharide
formation were calculated by fitting the data to a simple model