Food-Processing Metabolomics Reveals Nutrient-Derived Adduct Formed by Ethylene Oxide Fumigation

Introduction: Ethylene oxide (ETO) is a highly reactive sterilizing agent classified as a carcinogen, and its use in foods is prohibited in many countries. Current regulatory monitoring relies on detection of ETO and/or 2-chloroethanol (2CE), a reaction product formed with chloride ions. However, ETO is highly volatile and difficult to detect directly, and 2CE may occur naturally or arise from non-food-related sources, raising concerns regarding its specificity as a fumigation marker. This study applied a food-processing metabolomics strategy to identify novel chemical markers generated through reactions between ETO and endogenous food constituents.

Methods: A metabolomics-based analytical approach was applied to investigate chemical changes induced by ETO fumigation of cumin (Cuminum cyminum L.) seeds. Polar metabolites were extracted and derivatized, followed by GC–MS-based metabolomic profiling. Principal component analysis (PCA) was used to discriminate fumigated and non-fumigated samples. A fumigation-specific compound was further characterized by high-resolution GC–QTOF–MS.

Results and Discussion: PCA clearly discriminated fumigated from non-fumigated samples based on metabolomic profiles. A characteristic metabolite was consistently detected only in fumigated samples. Accurate mass and fragmentation analyses indicated that the metabolite corresponded to a malic acid–ETO adduct. In vitro fumigation of authentic malic acid reproduced identical chromatographic and spectral features, confirming its formation. Furthermore, malic acid–ETO adduct was detected in a variety of other ETO-treated spices.

Conclusions: This study provides direct evidence that ETO fumigation induces formation of a nutrient-derived adduct in foods. The identified malic acid–ETO adduct represents a promising new marker for verifying ETO fumigation, offering an alternative approach beyond conventional 2CE-based monitoring. The proposed marker provides a complementary approach to conventional residue monitoring based on ETO and 2CE.

Reference: Nakamura, K. et al. Identification of a chemically modified nutrient for direct evidence of ethylene oxide fumigated foods, Food Hygiene and Safety Science, in press.