Exploring Lipid Degradation and Spatial Distribution of Rice during Storage: Based on Multi-Scale Microscopic Imaging, Lipidomics and DESI-MSI

Understanding how molecular changes drive structural deterioration is essential for clarifying rice quality loss during storage. Paddy rice stored for 0–2 years under brown rice (BR) and polished rice (PR) systems was analyzed using multiscale microscopy, LF-NMR, lipidomics, and DESI-MSI to investigate lipid degradation and spatial redistribution during storage. Both BR and PR showed progressive surface darkening and reduced transparency during storage. BR exhibited bran-layer cracking and lipid leakage, whereas PR showed increased surface roughness and internal particle aggregation. Total quantified lipids decreased during storage, accompanied by aleurone membrane deterioration and lipid redistribution. Lipidomics identified 666 lipid species and showed distinct remodeling patterns between BR and PR. DESI-MSI further visualized 87 lipids with clear tissue-specific distributions. Outer-layer lipids mainly underwent fatty acid turnover, whereas endosperm lipids were characterized by glycerophospholipid degradation and remodeling. These findings provide spatially resolved insight into lipid-mediated rice quality deterioration during storage.