Impact of Feedstock, Parboiling Condition, and Nutrient Concentration on Simultaneous Fortification of Two U.S. Long-Grain Rice Cultivars with Iron and Zinc James Patindol, 1 Ligia Fragallo, 1 Ya-Jane Wang, 1,† and Alvaro Durand-Morat 2 ABSTRACT Cereal Chem. X(X):X–X This work investigated the effect of parboiling on simultaneous fortifica- tion of rice with iron (Fe) and zinc (Zn) using rough rice and brown rice as feedstocks. Three fortificant concentrations (0, 100, and 200 mg/L for both Fe and Zn) were tested, and two long-grain rice cultivars (CLXL745 and RoyJ) were used as test samples. Cultivar had little impact on the retention of Fe and Zn; steaming combined with soaking significantly increased the migration of Fe and Zn into the endosperm compared with soaking only. The Fe and Zn contents of the resultant parboiled head rice were related to the initial concentrations in the soaking water and were 7.2–17.6 and 21.8–31.9 mg/kg, respectively, when rough rice was used as a feedstock, and they significantly increased to 32.4–84.9 mg/kg for Fe and 45.8–78.4 mg/kg for Zn when brown rice was used as a feedstock. Mineral retention after simulated washing was 87.5–95.1% for Fe and 81.1–84.3% for Zn. Dilute- HCl extractability as an indicator of mineral bioavailability was 66.2–72.4% for Fe and 83.4–92.0% for Zn. The results indicate that brown rice is a better feedstock than rough rice for mineral fortification via parboiling. Rice is the staple food of more than 3.5 billion people worldwide (Khush 2013); hence, it is a potentially valuable vehicle for micro- nutrient fortification that will facilitate a large-scale delivery of minerals and vitamins of particular interest. Micronutrient fortifi- cation is one of the strategies employed by the World Health Or- ganization and the Food and Agriculture Organization of the United Nations to eliminate micronutrient malnutrition in the world, es- pecially in developing countries (Muthayya et al. 2012). Iron, iodine, folate, vitamin A, and zinc deficiencies are the world’s five most widespread micronutrient deficiencies; all these deficiencies are com- mon contributors to poor growth, intellectual impairments, perinatal complications, and increased risk of morbidity and mortality (Bailey et al. 2015). The milling process depletes a considerable portion of the endogenous minerals and vitamins in the bran from brown rice to produce milled white rice. Consequently, populations that subsist on rice as a dietary staple are at high risk of micronutrient deficiencies (Muthayya et al. 2012). The success of rice micronutrient fortification has remained a technological challenge. Technologies that are currently available for mineral and vitamin fortification of rice include dusting, coating, and extrusion (Muthayya et al. 2012; Steiger et al. 2014). Rice should be fortified with micronutrients that are available for absorption by the body and that remain stable during processing, storage, transport, preparation, and cooking. The selection of micronutrients also de- pends on their legal status, price, sensory acceptability, and product forms that are appropriate for the fortification technology to be used (Steiger et al. 2014). The cost of micronutrient fortification using cur- rent technologies is reportedly 1.5–3.0% of rice retail price (Muthayya et al. 2012), yielding an overall cost of around $10–20 per ton. Parboiling has been known to enhance the nutritional quality of rice as a result of changes in starch structure and the inward dif- fusion of micronutrients from the bran into the starchy endosperm (Juliano 1993). In recent years, parboiling has also been employed as a strategy to fortify rice with micronutrients at laboratory and pilot scales, using a single nutrient or a combination of two or more nu- trients. Micronutrients that have been used to fortify rice through par- boiling include chromium, folate, iodine, iron, vitamin A (b-carotene), and zinc (Tulyathan et al. 2007; Prom-u-thai et al. 2008, 2010, 2011a, 2011b; Kam et al. 2012; Thiruselvam et al. 2014; Yulianto et al. 2015). In certain parts of South Asia, Africa, and Latin America, parboiled rice is the dietary staple. Therefore, fortification-parboiling could be a viable and cost-effective approach for delivering micronutrients to consumers in the aforementioned regions where commercial-scale in- frastructure is already in place, and consumers do not need to modify their eating habits (Prom-u-thai et al. 2011b). Rough rice (paddy) is often used as a feedstock for parboiling. For a fortification-parboiling process to be successful, the fortificant molecules should be able to pass through some layers of protective barrier (hull, pericarp, seed coat, nucellus, and aleurone layer) that enclose the starchy endosperm of the rice kernel and be retained upon milling. It is inferred that removing the hull may enhance the penetration of the fortificant molecules into the starchy endosperm. Thus, this research was conducted to compare the effectiveness of the fortification-parboiling process using rough rice (kernels with hull) and brown rice (kernels without hull) as feedstocks. Iron and zinc were chosen as fortificants because iron deficiency is the most common nutritional deficiency in the world, and zinc deficiency is associated with poor growth and development and impaired im- mune response (Whittaker 1998). Iron and zinc deficiencies are widespread in Asian and African countries (Prasad et al. 2014), where parboiled rice is the staple food. The mineral retention and solubility, milling yield, milled rice color, and pasting properties of the fortified-parboiled products were characterized. MATERIALS AND METHODS Rice Cultivars. Rough rice samples (2014 crop, approximately 12% moisture content) of two long-grain cultivars, CLXL745, a hybrid, and RoyJ, a pureline, were provided by Riceland Foods (Jonesboro, AR, U.S.A.). Because the bran layer thickness may be different between hybrid and pureline cultivars (Siebenmorgen et al. 2006), both were included in this study. The samples were cleaned with a dockage tester (Carter-Day, Minneapolis, MN, U.S.A.) to remove empty kernels, straws, chaff, and other contaminants. The cleaned rough rice was divided into two lots. One lot was set aside for fortification-parboiling using rough rice as a feedstock. Another lot was dehulled with a Satake THU-35 dehusker (Satake Corporation, Hiroshima, Japan) to obtain brown rice. Green (immature), pecked, and other damaged kernels were manually removed from brown rice. The milled rice was characterized for apparent amylose content by iodine colorimetry (Juliano 1971), crude protein content according to an AACC International Approved Method, and onset gelatinization temperature with a differential scanning calorimeter. The amylose content, protein content, and onset gelatinization temperature were 21.2%, 6.8%, and 73.3°C, respectively, for CLXL745, and 24.0%, 5.3%, and 73.6°C, respectively, for RoyJ. † Corresponding author. E-mail: yjwang@uark.edu 1 Department of Food Science, University of Arkansas, 2650 N. Young Avenue, Fayetteville, AR 72704, U.S.A. 2 Department of Agricultural Economics and Agribusiness, 217 Agriculture Building, University of Arkansas, Fayetteville, AR 72701, U.S.A. https://doi.org/10.1094/CCHEM-05-17-0115-R © 2017 AACC International, Inc. 1