Inactivation of microbial and pest contamination in post-harvest wheat by plasma-activated gas

Microbial contamination and pest infestation frequently occur during post-harvest storage of wheat, leading to significant losses in both quantity and quality. Conventional management strategies, including thermal and chemical methods, are effective, however, they often compromise the sensory properties of wheat or cause residues of hazardous chemicals. Plasma-activated gas, as a plasma-derived form, could inactivate microorganisms and can be developed as a non-selective, eco-friendly alternative for wheat preservation. In this study, different plasma-activated gases were used to inactivate microorganisms and pest Sitophilus zeamais artificially contaminating wheat in the treatment chamber, and the H-Mixed-gas demonstrated superior inactivation efficacy on both microorganisms, including bacteria and fungi, and pest S. zeamais compared to other plasma-activated gases. Following 4 consecutive cycles of H-Mixed-gas treatment, no notable changes were observed in the structural integrity, physical quality, or processing quality of the wheat grains, with slight alterations to the surface functional groups of the grains, and only trace amounts of reactive species remained on the grains. Moreover, the treatment with the H-Mixed-gas could simultaneously inactivate various contaminants in grains, without mutual interference. Therefore, plasma-activated gas treatment supplied an efficient and safe technology for post-harvest wheat preservation.