Non-starch polysaccharides and bound phenolic acids from native and malted finger millet (Ragi, Eleusine coracana, Indaf - 15)

Nature of non-starch polysaccharides (NSP) and bound phenolic acids from native and malted ragi were studied using a recently-released hybrid variety of ragi, (Indaf-15). Yields of water-soluble NSP, hemicellulose-B and cellulose polysaccharides increased upon malting whereas a substantial decrease in the yield of hemicellulose-A was observed. Hemicellulose-B is the most viscogenic and its relative viscosity decreased from 3.04 to 1.98 upon 96 h of malting, whereas the solubility and viscosities of the rest of the NSP increased upon malting. The major sugars identified in all the NSP fractions were arabinose, xylose, galactose and glucose. A one- to two-fold decrease in arabinose was observed in all the NSP upon malting except for the alkali-insoluble residue wherein a decrease of glucose was observed. A progressive decrease in the pentose to hexose ratio was observed, indicating mainly pentosan degradation during malting, whereas an increase in the pentose to hexose ratio was observed in the alkaline-insoluble residue (AIR). Ferulic, caffeic and coumaric acids were identified as the major bound phenolic acids in native ragi and one- to two-fold decrease was observed in their contents after 4 days of malting.