Molecular hydrogen as a redox-active regulator of toxic chemical foodborne hazards: Delivery technologies and matrix-dependent mechanisms.

Toxic chemical hazards in food systems, including biogenic amines (BAs), nitrites, and heavy metals, pose persistent risks due to their formation, transformation, accumulation, bioaccessibility, and toxicity, which are influenced by redox imbalance, microbial metabolism, and matrix-dependent microenvironmental conditions. Molecular hydrogen (H2), a small redox-active molecule with selective reactivity toward highly reactive oxidants, has attracted increasing attention as a potential strategy for regulating these hazardous chemical species. This review summarizes recent advances in H2 research on BAs, nitrites, and heavy metals, with an emphasis on the redox-dependent mechanisms that govern hazard formation and mitigation in food systems. It further examines physical and chemical strategies for H2 delivery, including hydrogen-rich water, nanobubble HRW, hydrogen fumigation, hydrogen-modified atmosphere packaging, and chemically driven in situ generation, which influence hydrogen availability, persistence, and reactivity in different food matrices. Current evidence indicates that H₂ mitigates toxic chemical foodborne hazards through several interconnected redox-dependent processes. These processes involve stabilization of the redox microenvironment, attenuation of highly reactive oxidants and radical-mediated reactions, modulation of microbial bioenergetics and stress responses, regulation of nitrogen transformation, and alterations in metal speciation, matrix binding, and digestion-stage release. Through these regulatory effects, H₂ limits biogenic amine formation by reducing precursor release and amino acid decarboxylation. It also modulates radical-mediated, enzymatic, and microbial processes involved in nitrite accumulation. For heavy metals, H₂ affects redistribution, speciation, matrix binding, and digestion-stage bioaccessibility. Overall, H2 mitigates toxic chemical foodborne hazards through modulation of redox-dependent chemical and microbial pathways, providing a mechanistic basis for developing safer and cleaner food technologies.