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Abstract

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 (ZnSO4). 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.

Modifying the Parboiling of Rice to Remove Inorganic Arsenic, While Fortifying with Calcium

“…In Bangladesh the vast majority of rice is consumed parboiled. Parboiling involves soaking the rough rice (i.e., with husk intact) overnight in ambient water and then boiling or steaming, followed by sun-drying, dehusking, and then milling. − This gelatinizes the starch that constitutes the endosperm, causing the grain to expand, leading to the separation of the two-halves of the hull. Parboiling can be used to fortify rice with B-vitamins and mineral nutrient by adding them to the parboiling water .…”

“…Parboiling involves soaking the rough rice (i.e., with husk intact) overnight in ambient water and then boiling or steaming, followed by sun-drying, dehusking, and then milling. − This gelatinizes the starch that constitutes the endosperm, causing the grain to expand, leading to the separation of the two-halves of the hull. Parboiling can be used to fortify rice with B-vitamins and mineral nutrient by adding them to the parboiling water . The consequences of parboiling procedures on rice arsenic content has been characterized in Bangladesh, showing that there is little loss of total arsenic due to typical processing .…”

“…However, there has been no attempt to alter parboiling protocols to see if arsenic or cadmium can be removed. A recent study showed that parboiling wholegrain, as opposed to rough rice, caused fortification with iron and zinc . The migration of iron and zinc in wholegrain rice during parboiling was attributed to removal of the husk that acts as a diffusion layer between the external medium and the wholegrain.…”

“…The altered dynamics of iron and zinc migration on the parboiling of wholegrain rice is a very interesting development, and may have consequences for inorganic arsenic and cadmium mobility in rough versus wholegrain rice during parboiling. The husk is specifically high in inorganic arsenic, , and is potentially a diffusions barrier to the wholegrain it encases, as for iron and zinc .…”

Zinc Accumulation and Distribution in Germinated Brown Rice

“…It could make some key enzymes activated and released under appropriate temperature and humidity condition. Steep brown rice using Zn solution firstly (Prom-U-thai et al, 2010), then germinate it in an incubator. During this procedure, brown rice absorbed exogenous inorganic Zn and transformed it into O-Zn by combining with macromolecules so as to increase O-Zn content and Zn bioavailability.…”