EVALUATION OF MONO-, DI- AND OLIGO-SACCHARIDES OF STAPLE INDIAN GRAIN FLOURS

In this study, investigation of fourteen most common and traditionally used Indian staple grain flours: wheat, white rice, kutki rice, maize, maida, besan, sattu, little millet, quinoa, soybean, jowar, bajra, sooji and ragi was undertaken for the assessment of mono-(namely glucose, fructose and galactose) and di- (namely sucrose) and oligo-saccharides (namely raffinose, stachyose and verbascose), with a special interest on the indigestible flatulence producing Raffinose Family Oligosaccharides (RFOs). The soluble saccharides were extracted with ethanol and evaluated by calorimetric and high-performance liquid chromatography (HPLC) methods. The results showed that among the investigated flours, total RFOs content on dry matter (DM) basis ranges from 0.07 (maize) to 12.61 mmol/100 g DM (chickpea). Within RFOs, raffinose was the major sugar (0.1 to 8.04 mmol/100 g DM), followed by stachyose (negligible to 6.3 mmol/100 g DM) and verbascose (negligible to 0.14 mmol/100 g DM), except for soybean wherein the major RFO was stachyose. The observed sucrose content ranges from 0.05 (maize) to 6.32 mmol/100 g DM (quinoa). Within mono-saccharides: glucose content ranges from negligible (chickpea, little millet, quinoa, pearl millet and sooji) to 3.64 mmol/100 g DM (soybean), galactose content ranges from negligible (white rice, maize, sattu, quinoa, white millet, sooji and finger millet) to 1.72 mmol/100 g DM (chickpea) and fructose content ranges from negligible (chickpea, sattu, little millet, quinoa, soybean, sooji and finger millet) to 0.99 mmol/100 g DM (white rice). From the obtained results, the investigated grains can be classified as per the content of water soluble saccharides and accordingly a glycemic index and anti-flatulence chart can be prepared as a ready reference for dietary guidelines.