Manufacture and Prebiotic Potential of Xylooligosaccharides Derived From Eucalyptus nitens Wood

Abstract

Mixtures of xylooligosaccharides (XOS) were manufactured from Eucalyptus nitens samples by hydrothermal processing. In order to obtain a product suitable to be used as a prebiotic, the liquors obtained were subjected to a refining sequence consisting of a two-step membrane filtration followed by anion exchange and freeze-drying. The process proposed allowed to obtain a highly refined product mainly made up of a mixture of substituted XOS with a degree of polymerization, DP3–10, which was evaluated for its prebiotic potential by in vitro fermentation assays. Their effects on the microbiota composition and the metabolic activity were assessed along the fermentation time and compared to fructooligosaccharides (FOS, a gold standard prebiotic), using fecal inocula from donors belonging to two age-groups (young and elderly). Significant and similar increases were observed in most of the bacterial groups considered (including Bifidobacterium spp. or several butyrate-producers) in both XOS and FOS in vitro interventions, although XOS resulted in significantly higher increases in total bacteria and lower rises in Clostridium clusters I and II than FOS. Regarding the metabolic activity, higher amounts of total organic acid (TOA; 150 vs. 110 mM) and higher total short-chain fatty acid (SCFA)/TOA ratio (0.88 vs. 0.70 mol/mol) were achieved at 28 h using XOS as a carbon source in comparison with FOS. Moreover, both substrates resulted in different metabolite profiles. Higher percentages of acetate and propionate were achieved when XOS were used as substrates, whereas FOS resulted in slightly higher concentrations of butyrate. No differences were found between both age-groups. Taking together these results, it can be concluded that XOS produced from E. nitens by a biorefinery-based approach led to, at least, similar prebiotic activity as that observed with FOS.

In Vitro Assessment of the Prebiotic Potential of Xylooligosaccharides from Barley Straw

“…The highest concentrations of this acid were obtained at 30 h (65.2 mM) in fermentations, showing significant differences (p ≤ 0.05) as compared to FOS at the same fermentation time (38.3 mM). The results observed in this work are lower than in a previous study using XOS derived from corn stover, vine shoot, or Eucalyptus nintes wood at similar times [40,44,45], but higher than those obtained from corn straw [46]. Acetic acid plays a key role in the regulation of epithelial cell division.…”

“…Another SCFA that is very important in the gut environment is propionic acid. In this case, 12.2 mM were produced at 30 h. In many assays described in the literature, there is a controversy as to whether propionic acid was the second or third main organic acid produced in fermentation [34,40,44,45]. These differences might be related to the source and chemical structure of XOS.…”

Xylo-oligosaccharides, fermentable sugars, and bioenergy production from sugarcane straw using steam explosion pretreatment at pilot-scale

“…To isolate XOS from the crude SE liquor, a two-step membrane filtration followed by anion-exchange could be used. These membrane filtration steps assist in removing carbohydrate-based degradation compounds such as HMF and furfural as well as reduce potential fouling effects on the ion exchange resins, enabling a highly refined XOS product (with DP 3-10) eligible as a prebiotic food or feed ingredient (Míguez et al, 2021).…”

Production, Properties and Applications of Xylooligosaccharides (XOS): A Review

“…Autohydrolysis products were obtained after cooling and centrifugation. Mixtures of substituted XOS obtained were refined through a two-step membrane filtration and ion exchange [20].…”