Chlorine dioxide fumigation of grains: is it a complete solution?

Storage of grains is essential for crop production, market positioning, profitability, and food security. The depleting options in efficient fumigants for grain storage have fueled the search for alternatives. Amongst these, chlorine dioxide (ClO2) is a viable option considering the multiple functions it offers in addition to disinfestation. While ClO2 has been evaluated primarily for insect control in stored grains, a unified assessment of its efficacy against emergent foodborne pathogens, mycotoxin degradation, pesticide residue mitigation, dry surface biofilms and enzyme stability is lacking to establish ClO2 as a holistic fumigant. In this review, we synthesize current knowledge on the application of ClO2 gas in grain matrices. We place particular emphasis on its use against major grain borne pathogens (Salmonella and Shiga toxin producing E. coli) and on its potential for mitigating persistent mycotoxin contamination in stored grains. Mass transfer of ClO2 in bulk grains is probed and physicochemical properties are compared with existing fumigants to assess ClO2 candidacy. In addition, we outline future opportunities for using ClO2 to attenuate pesticide residues, modulate quality relevant enzymes and disrupt dry surface biofilms. Ultimately, a strategy to optimize ClO2 as a multifunctional fumigant for future application and research gaps is identified.