Systematic Investigation of the Reduction of Inorganic Arsenic and Bioactive Nutrients in Rice with Various Cooking Techniques

The objectives of this study were to investigate the effect of polishing, stirring and rinsing, soaking, or pressure-steam cooking on total organic and inorganic arsenic content and to measure daily inorganic arsenic exposure and nutrient values from consumption of rice prepared under the optimal process. With increasing numbers of rinses and times stirred per rinse, the total arsenic content significantly decreased by 27.6% in brown rice and 39.0% in white rice with 10% degree of polishing (10DOP%). The increase in ratio of water to rice from 1.5:1 to 6:1 reduced total arsenic by 4.4 to 7.5%, depending on soaking time. The total arsenic concentrations found in samples prepared using the optimal process for cooked brown rice and for white rice with 5DOP%, 7DOP%, and 10DOP% were 56.1, 49.6, 52.0, and 42.0%, respectively, compared with those after bran residues were removed. The concentration of total dietary fiber in 10DOP% white and brown rice was 0.34 mg/100 g (54.7% reduction) and 2.52 mg/100 g (24.8% reduction) after the cooking process, respectively. Results from the current study suggest that the optimal cooking process could maximize the reduction of arsenic contents and, at the same time, minimize the loss of nutrients from rice.