Development of a Diffusion Based Fortification System and Process to Improve the Iron and Zinc Content in Rice

Abstract

Micronutrient deficiencies have been identified as a key issue regarding human health in many parts of the world. This study describes how the micronutrient content of rice can be improved with a modification to rice parboiling. Two paddy varieties (BG 352 and BG 358, respectively) initially tested for water uptake during hot soaking (70 ºC) under vacuum (- 0.6 bar), showed significantly (P<0.05) higher water uptake (28.5% and 26.15%, respectively) than that of non-vacuumed conditions (25.24% and 25.45% respectively), exhibiting the effectiveness of water diffusion into the rice grains through the cleared pores under vacuum. Hot soaking (70ºC) in 400 ppm solutions (Fe2+ or Zn2+) under vacuum (-0.6 bar) during the first hour, followed by 2.5 h under atmospheric pressure exhibited the optimum fortification (Fe2+: 46.59±0.37 ppm and Zn2+: 67.24±1.36 ppm) with a greater significance (P<0.05) compared to the controls (Fe2+: 38.84±0.62 ppm and Zn2+: 52.55±0.55 ppm) complying the World Food Program specifications for iron and zinc fortified rice, (40-48 mg/kg and 60-72 mg/kg respectively). This finding was further confirmed by the XRF images which showed fortificants distribution in the endosperm. There were no significant (P>0.05) differences among both Fe2+ and Zn2+ contents in fortified rice after washing (Fe2+: 44.31±1.2 ppm and Zn2+: 66.64±0.6 ppm), confirming their greater retention. Scanning Electron Microscope images proved that the rice kernel has porous areas which may facilitate water uptake into the middle parts of the endosperm during soaking. This technology has obtained international patent and is being used for commercial production of fortified rice.