Effect of gaseous chlorine dioxide treatment on the quality of rice and wheat grain

Gaseous chlorine dioxide (ClO2), which is a strong disinfecting agent with strong oxidation properties and penetration ability, is used to control insect pests and fungal contamination in stored grains. However, the effect of gaseous ClO2 on stored grain has yet to be reported. In the present study, we exposed rice and wheat seeds to several concentrations of ClO2 gas for various durations and found that the viability of rice was affected less than that of wheat. After 100 ppm of gaseous ClO2 for 12 h, the normal rice seedling rate was not significantly different than that of the control. However, that of wheat was significantly decreased. We also measured the ClO2 residueon stored rice and wheat after 200 ppm of gas treatment for 24 h. After 10 days of storage following the treatment, ClO2 and chlorine were not detected on either rice or wheat. Chlorite was detected on rice at 0.22 mg/kg of grain; however, it was not detected on wheat. These results suggest that gaseous ClO2 treatment affects the viability of rice and wheat seed but leaves minimal chemical residue.