A comparison of micronutrient elements in cooked white, brown and parboiled rice using synchrotron micro-X-ray fluorescence imaging

Rice is a staple food for over half the world's population. This study uniquely investigates the spatial distribution of key micronutrients (Cu, Mn, Fe, Zn) in cooked brown, white, and parboiled rice using Synchrotron Micro-X-ray Fluorescence (sXRF) for the first time. Complementary analysis with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) validates bulk elemental concentrations. Results from this dual-approach study reveal significantly higher micronutrient concentrations in brown rice compared to white or parboiled rice, with nutrients predominantly localised in the peripheral layers and minimal presence in the endosperm. Notably, sXRF imaging identified nutrient-rich pockets within the grain periphery, offering new perspectives on nutrient distribution beyond peripheral accumulation. Additional insights include the impact of rice section thickness (50 and 150 μm) and beam dwell times (0.5 and 30s) on sXRF sensitivity and resolution, highlighting trade-offs in detection capabilities, advancing our understanding of micronutrient localisation in cooked rice.