Manufacture and evaluation of xylooligosaccharides from corn stover as emerging prebiotic candidates for human health

Corn stover samples were subjected to hydrothermal treatment in order to solubilize the hemicellulosic fraction, obtaining hemicellulose-derived saccharides with up to 11.7 g/L of xylooligosaccharides (XOS). Oligomers-containing liquors were nanofiltered by two-step membrane-based separation (discontinuous diafiltration and concentration) showing an increase in XOS concentration up to 21.94 g/L, purified by ion-exchange processing and freeze-dried, obtaining final products with up to 89% of purity. The presence of both substituted (with 4-O-methyl-glucuronic acid or acetyl substituents) and unsubstituted oligosaccharides, mainly made up of xylose and with a degree of polymerization in the range of 5-29, was observed in the purified products. The effects of the various XOS substrates on the metabolic activity and on the dynamics of the microbial populations were studied in media inoculated with human fecal sample. Short chain fatty acids generation and changes in the three selected bacterial groups (Bifidobacterium genus, Lactobacillus−Enterococcus and Bacteroides−Prevotella group) confirm the suitability of this work to obtain XOS fractions with potential functional properties for human health.