Inactivation of Salmonella Newport on blueberries by treatment with chlorine dioxide gas and its effect on blueberry qualities

The purpose of this study was to use chlorine dioxide (ClO₂) gas to inactivate Salmonella Newport on blueberries and observe quality changes of blueberries as affected by the treatment. Blueberries inoculated with S. Newport were treated with ClO₂ gas for 10 h ClO₂ gas was generated from either 1 or 2 mL of ClO₂ solution dropped in a sealed container and the container was hold at 12 °C or 25 °C. Within 30 min, Salmonella populations on blueberries treated with ClO₂ gas, regardless of treatment temperature and amount of ClO₂ solution, reduced below the detection limit (1.7 log CFU/sample) and the organism was eliminated within 30 min when 1 mL of ClO₂ solution was used to generate gas at 25 °C. After the ClO₂ gas treatment, blueberries were analyzed with an electronic eye. Color of untreated and ClO₂-gas treated blueberries are composed of 12 and 11 color codes, respectively. Out of the color codes, 7 codes of both blueberries in control and treatment groups are the same. ClO₂ gas treatment did not cause significant changes in Hunter's L, a, and b-value of blueberries. Hardness (g) of blueberries treated with ClO₂ gas for 30 min significantly increased; however final values were not significantly different from the values of untreated ones. As a result of this study, the ClO₂ gas successfully reduced S. Newport on blueberries without significant changes in their color and hardness.