Composition and structure of a mucilaginous polysaccharide extracted from black gram (Vigna mungo (L.) Hepper) during preparation of fermented dairy alternatives

A mucilage polysaccharide from black gram ( Vigna mungo ), isolated at different stages of a plant-based processing operation (grinding, enzyme treatment, fermentation, and centrifugation), was characterised using constituent sugar composition and glycosyl linkage analysis, NMR spectroscopy, and size-exclusion chromatography. The results showed that the polysaccharide was a rhamnogalacturonan-I, with a backbone of →2)-α-L-Rha p -(1→4)-α-D-Gal p A-(1→ comprising ∼ 17 % of the polymer, branched at O -4 of the Rha residues. The sidechains were mostly branched arabinan, together with lower proportions of type I galactan and type II arabinogalactan. The molecular weight (M w ), determined by size-exclusion chromatography coupled with multi-angle laser light scattering was extremely high (7.10–8.75 × 10 6 g/mol). The different processing methods did not result in major changes in constituent sugar composition, structure, or molecular weight of the isolated polysaccharide. This study provides the basis for further investigations for the use of black gram mucilage as a food hydrocolloid with potential beneficial human health outcomes.