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

Abstract

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.