Novel generation systems of gaseous chlorine dioxide for Salmonella inactivation on fresh tomato

Chlorine dioxide (ClO₂) is an antimicrobial agent used in fresh produce sanitation to inactivate a board range of pathogens. Compared to its aqueous form, gaseous ClO₂ has a stronger penetrating ability and therefore a greater inactivation effect. A novel ClO_2(g) generating method utilizes carbon dioxide and moisture naturally released from tomato during respiration to react with NaClO₂ for ClO_2(g) generation has been proposed in our previous study. This study further developed two novel generation systems (i.e., electrospun fiber and releasing film) for the method applications in reality. In this study, the physical properties (i.e., viscosity, conductivity, pH and surface tension) of different poly-ethylene oxide (PEO) polymer solutions (i.e., 2%, 3%, 4% PEO and 3% PEO with 0.15%, 0.3% NaClO₂), the morphology and diameter distribution of electrospun fibers produced as well as the loading efficiency of NaClO₂ onto the fibers were investigated. The successful generation of ClO_2(g) from the two developed systems were observed. Four log CFU Salmonella/fruit inoculated on the surface were significantly reduced (p < 0.05) to undetectable level (<5 CFU/fruit) within 2 days under both systems and the surface color and firmness of the fruits were not impacted (p > 0.05) during the entire storage period (14 days for 10 °C and 7 days for 22 °C). The information can be utilized for Salmonella safety enhancement on fresh tomato during storage, transportation and retail stages. It also provides insights for the further applications of the generating method on many other fresh produce as well as on many other pathogens.