Zinc fortification of whole rice grain through parboiling process

Chanakan Prom-u-thai1*, Benjavan Rerkasem1, Ismail Cakmak2, Longbin Huang3 1Agronomy Department, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand 2 Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul 34956, Turkey 3 The University of Queensland, Center for Mined Land Rehabilitation, St Lucia, QLD 4072, Australia Abstract The present study evaluated the effectiveness of Zn fortification in parboiling process for improving Zn density in parboiled-polished rice and its potential bioavailability in rice-based human diet. The result showed that fortification of Zn in the whole paddy rice grain during parboiling process with 50-400 mg Zn kg-1 paddy rice increased Zn concentration in polished-parboiled rice from 1.3 to 4.5 times of those in unfortified parboiled rice. The added Zn rapidly penetrated into parboiled rice grains in the initial soaking process before saturation. There was an exponential correlation between Zn concentrations in unpolished (r= 0.63) (p< 0.01) and polished rice (r= 0.30) (p< 0.05) and soaking time. Zinc concentrations in unpolished rice were linearly correlated with Zn concentration in the polished rice (r= 0.60) (p< 0.01). Moreover, more than half of the added Zn is retained after a simulated washing process before cooking, ranging from 64-100%. In the Zn fortified parboiled rice, 57-100% of Zn in polished rice grain was soluble in dilute acid, indicating a high potential Zn bioavailability for human intake, but further in vivo investigations are required to confirm this potential. The results suggest that the established parboiling technique in parboiled rice industry has a great potential for Zn fortification to improve the density of Zn in parboiled rice grain and nutritional value for human base diets, in addition to Fe fortification as reported previously (Prom-u-thai et al., 2008, 2009). The benefit of Zn fortification in parboiled rice can be rapidly deployed to populations in South Asia who are major consumers of parboiled rice. Keyword: Zinc deficiency, Zinc fortification, Parboiled rice