Impacts of Packaging Design On Antimicrobial Effects of ClO2 Gas

In this study, Chlorine dioxide (ClO₂), an antimicrobial gas, is being considered for in-package vapor phase decontamination for fresh cut Romaine lettuce. The work addressed effects of packaging design on achieving uniform gas distribution, which could improve decontamination efficacy of ClO₂ gas. Three types of flexible bag with different interior designs were used to package Escherichia coli O157:H7 inoculated fresh cut lettuce. These bags contained gas reservoirs (GRs), which released 2 levels of ClO₂ gas, i.e., 4 and 8 mg ClO₂/kg lettuce per day, located in specific locations within the bags, i.e. from only one side of the bag, from both sides, and in the center (one-GRs, two-GRs, and middle-GRs, respectively). The samples were kept at 4^ºC and stored for 1, 4, and 7 days. Reduction in cell population of E. coli O157:H7, from different sections of the bag, were determined. The results showed that ClO₂ gas in the package reduced population of E. coli O157:H7 up to 1.24 ± 0.09 log₁₀ CFU/g of lettuce and increasing the level of ClO₂ gas per day increased the log₁₀ CFU/g reduction of E coli O157:H7. The highest log₁₀ CFU/g reduction was found in the sample taken adjacent to GRs. The performances of bag with two-GRs proved that it was possible to achieve the same degree of disinfecting effect and still maintaining the appearance of the treated produce even by reducing ClO₂ dose to half. The study also indicated that increasing releasing spots per bag or maximizing gas releasing area could improve inactivation efficacy of antimicrobial gas inside the package. These findings could be used in the re-design of packaging systems such as bags for leafy green products that will include an antimicrobial gas as the mean to improve safety and prolong shelf-life. The use of ClO₂ gas in packaging system with optimal design could be an effective component in a hurdle strategy to compliment the sanitation process that takes place in the production line.