Prebiotic Activity of Purified Xylobiose Obtained from Ragi (Eleusine coracana, Indaf-15) Bran.

The role of prebiotics in improving human health
has attracted global attention and the research is mostly
focused on the strains belonging to the genera Bifidobacterium
and Lactobacillus. Non-digestible oligosaccharides
hold significant role in recent research due to their prebiotic
nature. Soluble polysaccharides (SP, 14.4%), isolated from
ragi bran consisted mainly of arabinose and xylose with
minor quantities of rhamnose, mannose, galactose and glucose.
Ragi bran SP subjected to purified endoxylanase (from
96 h ragi malt) treatment to obtain xylo-oligosaccharides
which were further purified on Biogel P-2 followed by
HPLC. The purified oligosaccharide yielded (RO-1; 17.9%)
was identified as xylobiose by electrospray ionization mass
spectrometry (282 ? 23 = 305) and 1HNMR. In vitro
studies carried out using Bifidobacterium and Lactobacillus
sp. proved the prebiotic nature of the crude xylo-oligosaccharides
(XOs) and RO-1. Acetate was found to be the chief
short chain fatty acid released during fermentation of both
crude XOs and purified xylobiose and 24 h bacterial culture
showed high xylanase activity (1020–1690 lU min-1).