Mineral profiles across the Iberian rice chain: from soil to grain.

Background:
Rice is a staple crop globally, and Spain is the second-largest producer in the EU. Its mineral composition is influenced by environmental factors, soil availability, and processing. While essential elements are vital, non-essential ones can pose health risks for consumers. This study evaluates the elemental profile of the soil-shoot-grain system across the main rice producing regions of the Iberian Peninsula to assess its nutritional and toxicological status.

Methodology:
The study analyzed commercial rice (brown, parboiled, and polished) and field samples (soil, shoots, and grains) from key regions: Andalucía, Aragón/Navarra, Cataluña, Extremadura/Portugal, Murcia, and Valencia. Concentrations of 13 essential and non-essential elements were quantified using ICP-MS. Statistical tests were applied to identify regional variations and the impact of grain processing.

Results:
Processing was the primary factor affecting mineral density, with brown rice showing significantly higher levels than polished or parboiled varieties. Significant regional differences were found: Andalucía had higher soil concentrations of Cu, Mn, Ni, and Cr, while Valencia led in soil P and Sr. In grains, Andalucía showed the highest Mn, Mo, and Zn levels. Importantly, toxic elements like Pb and Cr remained at trace levels, well below European safety limits.

Conclusions:
The elemental profile of Iberian rice is mainly modulated by industrial processing and geographic origin. Presumably, plant exclusion mechanisms effectively limit the translocation of non-essential elements to the grain, ensuring a safe product. Although polishing reduces toxic heavy metals, it also significantly decreases beneficial micronutrients. Overall, Iberian rice is confirmed as a safe and nutritionally valuable food source.