Cold plasma as a biochemical interceptor: redesigning the oxidative stability of pearl millet through targeted enzyme...

Pearl millet is highly susceptible to rapid post-milling deterioration due to an interdependent hydrolytic-oxidative cascade, yet a coherent mechanistic model integrating enzyme kinetics, grain microstructure, and interventions is lacking. This review proposes an integrative biochemical framework for rancidity, deconstructing the cascade into lipase-mediated hydrolysis, Lipoxygenase (LOX) -driven peroxidation, auto-oxidation, and microbial contributions within spatially co-localized lipid-enzyme domains. Within this framework, cold plasma (CP) is presented as a precision, non-thermal, multi-modal intervention whose efficacy and precision are dose- and matrix-dependent. Evidence from related cereal systems and model enzyme studies indicates that Reactive oxygen and nitrogen species (ROS/RNS) can oxidize catalytic residues, destabilize metal cofactors, and induce conformational changes; direct confirmation of these mechanisms in pearl millet remains limited, although CP treatment has been shown to reduce free fatty acid and hydroperoxide accumulation in pearl millet flour. Accordingly, CP is considered primarily as a surface-dominant intervention targeting exposed lipase and LOX, whereas its effects on starch, lipids, microbial populations, and viable-seed physiology are treated as secondary and treatment-dependent. Secondary effects include substrate shielding, matrix restructuring, microenvironmental modulation, and inhibition of pro-oxidant metals. These interactions redefine reaction kinetics, offer a mechanistic basis for reconciling the CP-induced pro-oxidation paradox and improve oxidative, functional, and sensory stability. Integrating plasma chemistry with spoilage mechanisms may support future optimization of CP-based stabilization, but predictive control remains to be demonstrated across pearl millet varieties, product forms, and reactor configurations.