Simultaneous fortification of rice with folic acid and β-carotene or vitamin A by limited-water parboiling

Rice fortification by parboiling has been used to fortify rice with a single or a combination of multiple nutrients. While several studies have demonstrated the success of rice fortification with minerals by the parboiling technique, the number of studies that used vitamins as fortificants is limited with varying results. A limited-water soaking method has been introduced as a feasible and more sustainable alternative to the conventional excess-water soaking in parboiling. This study investigated the application of limited-water soaking in the simultaneous fortification of rice with water- and fat-soluble vitamins. Pure and water-soluble forms of β-carotene and vitamin A were first compared to identify a more effective form to be combined with folic acid. Water-soluble forms of β-carotene and vitamin A were easy to incorporate into the soaking water and presented effective fortification without affecting rice milling quality, the amount of wastewater and solids in wastewater. Milled rice fortified with folic acid combined with water-soluble forms of β-carotene or vitamin A in the limited-water soaking method contributed to about 75% of the recommended dietary allowances (RDAs) for folic acid, about 173% (female) and 134% (male) of the RDAs for β-carotene, and to about 58% (female) and 45% (male) of the RDAs for vitamin A. Rice fortified with β-carotene showed a greater uptake and a more orange color compared to the others. Thus, fortification of rice with vitamins by limited-water parboiling is an efficient process to obtain fortified rice that can significantly increase vitamin intake with limited environmental impacts. [Display omitted] •Limited-water soaking improved rice vitamin uptake compared to excess-water soaking.•Head rice yield was neither affected by soaking method nor by fortificant.•Fortified rice can contribute to folic acid, β-carotene, and vitamin A intake.•Water-soluble fortificants had limited environmental impact and high vitamin uptake.•High β-carotene uptake resulted in a more orange color of fortified rice.