Simultaneous fortification of iron and zinc in parboiled rice kernel

Fortification with Fe or Zn during parboiling process can effectively increase the concentration of each of these nutrients in rice. As Fe and Zn are often both limited in the diet of rice eaters, the present study investigated the feasibility of simultaneous fortification of parboiled rice with Fe (Fe-EDTA) and Zn (ZnSO ). The samples were treated with solutions consisting of both elements at different Fe:Zn concentration ratios (as mg/l) in the ranges 50:50, 50:100, 50:150, 50:200, and 100:50, 150:50, 200:50. Parboiling resulted in a nearly 5-folds increase in the concentration of Fe and Zn in rice kernels, depending on the rice cultivars. The added Fe and Zn penetrated across the husk and aleurone layers into the endosperm tissue, with a close relationship between unpolished and polished rice in their Fe (r = 0.86, p < 0.01) and Zn concentration (r = 0.87, p < 0.01). All to nearly all of the fortified Fe (80-100%) and Zn (70-100%) were retained after a washing that simulated the common practice of a pre-cooking wash. The fortified Fe and Zn in the polished kernels were highly bio-accessible, which was 45-100% for Fe and 88-97% for Zn. These results show how Fe and Zn concentration in polished parboiled rice can be increased by simultaneous fortification with both nutrients during the parboiling process