The Effect of Gaseous Ozone Generated by Surface Dielectric Barrier Discharge on the Decay and Quality of Stored Onion Bulbs

An effective and eco-friendly technology is needed to prevent postharvest loss of onion bulbs during cold storage. This study investigated the effect of gaseous ozone on the decay and quality of onion bulbs during storage at 2 °C and 70% relative humidity for two months. Gaseous ozone was adjusted to a concentration of 1.27 ± 0.024 ppm in the storage room by generating a high voltage discharge in air. After two months of storage, gaseous ozone significantly reduced the counts of aerobic bacteria (e.g., Rahnella aquatilis) and fungi (e.g., yeast and mold) in the onion bulbs by 4 log (CFU g−1) and 0.92 log (CFU g−1) compared with those of an untreated control, respectively. The microbial reduction by gaseous ozone resulted in a lower rotten rate of the onion bulbs, which was less than 20.0% compared with that of the untreated control. Moreover, the ozone exposure extended the storage life of the onion bulbs by delaying its color change and softening during storage. Our results suggest that gaseous ozone can control the decay of onion bulbs safely during storage.