Comparative studies on storage stability of ferrous iron in whole wheat flour and flat bread (naan)

Whole wheat flour was fortified with premix containing ferrous sulfate, ethylenediamine tetraacetic acid and folic acid (20.0:20.0:1.5 ppm) and was stored at ambient temperature for 60 days. Naans (flat bread) were prepared from 0 ppm, 25 ppm, 50 ppm and 75 ppm ferrous iron-fortified flour samples at 10-day intervals and were analyzed for physicochemical constants and sensory evaluation. It was observed that flour containing 75 ppm ferrous sulfate contained the highest iron residues. The total iron in flour samples showed no significant difference, while ferrous iron significantly decreased in fortified flour (0.53-3.08%) and in the naans (0.42-3.48%) because of its oxidation to ferric iron during storage. The phytic acid content decreased (0.886-0.810%) significantly during the same storage period. Iron levels affected some sensory characteristics significantly (P < or =0.05), including color, texture, flexibility, chewability and overall acceptability of the naans, but not taste and flavor. The sensory attributes of naans illustrated that naans containing 50 ppm ferrous iron are more acceptable than those prepared with 75 ppm ferrous iron.