Physico-chemical characteristics of native and pancreatic alpha-amylase digested cereal and finger millet starches

The composition and pancreatic enzymic digestibility profiles of starches isolated from finger millet (ragi) (Eleusine
coracana, var. Ίndaf-15'), rice (Oryza sativa, var. 'Jaya'), wheat (Triticum aestivum, var. 'DPW - 225') and maize (Zea mays,
var. 'NAC - 6002') were determined. The gelatinisation temperature (65±3°C) and the elution profile of the starches were
comparable, the molecular weight of amylose for maize starch was higher than that of ragi, wheat and rice as determined on
Sepharose CL-2B. However, the differential scanning calorimetry thermogram showed higher range of melting, broad span
of endotherm with increased enthalpy of gelatinisation for maize starch followed by ragi, wheat and rice starches. Degree of
crystallinity varied for the above starches with maize starch (41.4%) significantly higher, followed by ragi (37.3%), wheat
(37.0%) and rice (35.8%). Pancreatic α-amylase digestibility of cereal starches was better than their respective flours. Least
digestibility was observed for maize starch followed by ragi, wheat and rice starches. Maltose, maltotriose and maltotetraose
were the major oligosaccharides liberated from the starches upon pancreatic α-amylolysis.