A method of partial digestion of raw milled rice (Oryza sativa) was validated for the determination of inorganic nutrients (Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn) by inductively coupled plasma optical emission spectrometry. Based on hydrolysis with HCl, the method is simple and relatively fast, presenting satisfactory characteristics of performance. This method was used in the preparation of 40 raw milled rice samples commercialized in the state of São Paulo, Brazil. Emission spectrometry was applied to determine the mean contents and standard deviations of Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn (in mg.100 g-1 rice), which were 4.31 ± 0.44, 0.22 ± 0.10, 0.32 ± 0.08, 58.0 ± 15.0, 26.1 ± 5.7, 1.06 ± 0.26, 1.78 ± 0.55, 92.1 ± 15.2, and 1.24 ± 0.18, respectively. These results were compared with seven food composition tables available in the literature, which revealed discrepancies for Ca, Fe, Na, and K. Our data were also used to estimate the contribution of Ca, Cu, Fe, Mg, Mn, P and Zn contained in daily rice consumption to the Recommended Daily Intake (RDI). It was found that rice contributes significantly to the RDI, especially of Mn, Cu, and Zn, particularly in view of the average daily consumption of rice per person in Brazil.
milled rice; inorganic nutrients; digestion method; emission spectrometry; food composition table; Recommended Daily Intake
