Influence of decortication, popping and malting on bioaccessibility of calcium, iron and zinc in finger millet

Finger millet is a rich source of calcium and other minerals. The presence of high amounts of phytates, polyphenols and dietary fibre, may lower the bioaccessibility of minerals. The present study was aimed to determine the influence of decortication, popping and malting on bioaccessibility of calcium, iron and zinc in finger millet. The seed coat fraction of the millet was also included in the studies. Bioaccessibility of minerals was estimated by equilibrium dialysis method while phytic acid by colorimetric method. Polyphenols and dietary fibre were estimated by Folin-Ciocalteu and enzymatic methods respectively. Decortication decreased the total mineral contents, but increased the bioaccessibility of calcium, iron and zinc by 15, 26 and 24 g/100 g respectively. Popping decreased the bioaccessible calcium by about 10 g/100 g and increased that of iron by 5 and 14 g/100 g respectively in native and decorticated millet. No significant increase in bioaccessibility of zinc was observed on popping the decorticated millet but native millet showed an increase of 18 g/100 g. Malted millet showed higher values of bioaccessibility for all the minerals while seed coat fractions exhibited comparatively lower values, because of high proportion of inhibitory factors. Total phytic acid, polyphenols and dietary fibre decreased significantly on decortication and malting.

► Studies of processing conditions on bioaccessibility of calcium, iron and zinc in finger millet. ► Decortication improved the bioaccessibility of calcium, iron and zinc. ► Popping the native millet decreased calcium bioaccessibility and increased that of iron and zinc. ► Popping the decorticated millet decreased calcium and increased iron bioaccessibility.