Effect of germination-hydrothermal treatments followed by fractionation on inhibitory factors, β-carotene and iron-zinc bioaccessibility in pearl millet fractions

Abstract

Combination of strategies involving germination-hydrothermal treatments and fractionation were adopted to separates the native and treated grain into coarse (bran & germ) and fine (endosperm) fractions. The inhibitory factors, polyphenol oxidase, and phytase activity were higher in coarse fractions. On treatment, the phytic acid content in the coarse fraction decreases significantly by 49% while polyphenols decreased 13% in the fine fraction and increased 6% in the coarse fraction. Galloyls reduced by 21% and 48% in the fine and coarse fraction while catechols increased by 74% in the fine fraction and reduced by 27% in the coarse fraction. In the fine fraction, the soluble and insoluble fibre increased by 27.8% and 28.7% while in the coarse fraction is reduced by 23.5% and 24.1%. The β-carotene content reduced slightly in the coarse fraction with no variation in the fine fraction. Iron bioaccessibility was enhanced from 1.79 to 5.7% in the fine fraction and 3.06–6.05% in the coarse fraction. Zinc bioaccessibility increased from 15.44 to 24.67% and 18.59–47.6% in the fine and coarse fraction, respectively. In the treated coarse fraction the iron-zinc bioaccessibility increased due to a significant reduction in phytic acid (49%), insoluble dietary fibre (24%), galloyls (48%) and catechols (27%).