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

摘要

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 μU min⁻¹).