Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging for Spatially Resolved Food Safety Analysis

Food safety analysis still relies primarily on homogenization-based chromatography and spectroscopy. These methods remain indispensable for residue compliance and exposure assessment, but they collapse heterogeneous food structures into average concentration values. That limitation becomes important when the analytical question is not only whether a hazardous or safety-relevant molecule is present, but also where it is produced, how far it penetrates, and which tissue domains create local exposure hotspots. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) can address this interpretive gap by acquiring mass spectra from defined coordinates while retaining the spatial relationship between molecular signal and food structure. This review examines MALDI-MSI specifically as a source of spatial evidence for food safety, rather than as a general food-imaging technology. The literature is classified into three evidence levels: direct food-safety applications, indirectly relevant quality or plant-metabolomics models, and future opportunities that still require food-matrix demonstration. Direct examples are currently strongest for surface additives and selected processing contaminants, whereas food-matrix evidence remains sparse for mycotoxins, pesticide and veterinary-drug residues, packaging migrants, and allergens. Reported food and plant MALDI-MSI studies commonly operate from the low tens to hundreds of micrometers in lateral resolution, but sensitivity, limits of detection, and quantitative validity are highly analyte- and matrix-dependent rather than transferable across hazards. The central conclusion is therefore deliberately cautious: MALDI-MSI is not yet a replacement for validated LC-MS/MS or GC-MS regulatory assays. Its strongest current role is complementary, providing mechanistic localization, penetration profiles, hotspot mapping, and compartment-specific descriptors that bulk methods cannot supply. Reliable use requires explicit control of low-mass matrix background, ion suppression, analyte redistribution, molecular confirmation, calibration design, and orthogonal validation.