Application of isotope ratio mass spectrometry (IRMS) for food authenticity and food fraud detection: a comprehensive review.

Food fraud costs the global food system an estimated USD 30-40 billion a year and affects roughly one in ten traded products (Haider et al., 2024; Visciano & Schirone, 2021), yet conventional chromatographic, spectroscopic, molecular, and elemental methods share a blind spot: none provides intrinsic markers of geographic origin or production practice that resist falsification. Isotope ratio mass spectrometry (IRMS) measures natural variation in 13C/12C, 15N/14N, 2H/1H, 18O/16O, and 34S/32S imprinted on food by climate, geology, photosynthetic pathway, and agricultural practice; these signatures are difficult to reproduce synthetically. This review synthesises 333 peer-reviewed articles (1991-2024) retrieved through a PRISMA-guided Scopus search and analysed with VOSviewer and Bibliometrix; selected recent primary studies published after the bibliometric search period were incorporated into the narrative synthesis to update commodity-level evidence. Five research questions span fractionation theory, metrological conventions, EA/GC/LC-IRMS instrumentation, the diagnostic range of each isotope system, commodity-level applications, and chemometric interpretation. Annual output grew at 6.31%, North America and Europe dominating while Africa, South America, and Southeast Asia remain poorly sampled. Multi-isotope profiling with LDA or PLS-DA supports origin and production-regime discrimination across wine, honey, olive oil, dairy, meat, and cereals, with accuracy conditional on commodity, reference coverage, and validation design; the ∼14‰ δ13C gap between C₃ and C₄ plants underpins sugar-adulteration detection, and δ15N separates organic from conventionally fertilised produce. Analytical cost, isotopic overlap between climatically similar regions, thin reference databases, and continued reliance on leave-one-out cross-validation constrain routine enforcement. Closing these gaps requires broader multi-isotope databases, field-deployable analysers, harmonised proficiency testing, and baselines for plant-based, cultured, and insect-derived foods.