Influence of phytin phosphorous and dietary fibre on in vitro iron and calcium bioavailability from rice flakes

The study was undertaken with the objective of analysing the bioavailable iron, calcium and related constituents in rice flakes of four different thicknesses. Rice flakes of four different thicknesses were procured from four different commercial sources. They were analysed for moisture, mineral, iron, calcium, phosphorous, dietary fibre and phytin phosphorous using standard methods. Bioavailable iron and calcium were estimated using the equilibrium dialysis method. The thickness of flakes ranged from 0.08 to 1.20 mm for thin to thick flakes. The mineral content of the flakes ranged from 0.5 to 1.2 g, iron content from 3.38 to 6.86 mg and calcium content from 107 to 210 mg/100 g in samples of different thickness. Phosphorous (111–430 mg/100 g), phytin phosphorous (23–164 mg/100 g) and dietary fibre (5.64–11.5 g/100 g) reduced with the degree of flaking. The percentage of available iron ranged from 7% to 26% and that of available calcium from 8% to 25% from thick to thin flakes, but the differences were non-significant. Multiple regression analysis of the data showed a significant association of phytin phosphorous and dietary fibre (dependent variables) for binding of iron and calcium