Effect of Chlorine Dioxide Treatment and Storage in a Modified Atmosphere on the Inactivation of Cronobacter spp. on Radish Seeds

This study evaluated the inactivation of Cronobacter spp. on radish seeds using ClO2 treatment followed by storage in modified atmosphere (MA) for up to 4 days. Radish seeds were inoculated with Cronobacter spp. (6logcfu/g), adapted to nalidixic acid and treated with a ClO2 aqueous solution (0, 50 or 100L/mL). The seeds were then stored in an ambient air or MA (10% O2, 10% CO2 and 80% N2; 5% O2, 10% CO2 and 85% N2; or 10% O2, 0% CO2 and 90% N2) for up to 4 days. The Cronobacter spp. (6.2logcfu/g) populations on the radish seeds were reduced to 3.9, 3.8 or 2.6logcfu/g after treatment with 0, 50 or 100L/mL ClO2, respectively, and then to 3.7, 3.1 or1.6logcfu/g after 2h of drying. After 23 days of storage under MA (5 or 10% O2 with 10% CO2), no Cronobacter spp. were detected on the seeds treated with 100L/mL aqueous ClO2. More than 94.3% of the radish seeds germinated after ClO2 treatment followed by exposure to an MA, regardless of the ClO2 concentration. Practical Applications These results indicate that sprout seeds should be treated with sanitizers at an appropriate concentration. Sanitizer treatment of the seeds is more critical than following storage conditions for enhancing microbial safety. In addition, sprout seeds should be dried or stored after ClO2 treatment to increase its antimicrobial activity because a greater reduction in microbial populations occurred when the seeds treated with ClO2 were dried or stored than immediately after the treatment.