Purpose: The objective of this study is to develop new technology that enhances sterilization performance of low-concentrated ozone gas using micro-bubbles by surface-active agents.
Methods: The testing bacteria solution was prepared by mixing 20 g of commercial non-bleach bean sprouts and 90 ml of sterilized saline with a homogenizer. This solution included 5 log CFU/ml of viable bacteria, and pH was 6.5. Two types of ozone solutions were evaluated; 1) The mixed solution that consists of dissolved ozone water and the bacteria solution. 2) The micro-bubble ozone solution that was 400 ml of bacteria solution including 5 g/l triacetin as a surface-active agent, and 0.063 mg/l of ozone gas was aerated into solution with a flow rate of 1.0 l/min for 2.5 minutes using a porous glass. Viable bacteria surviving in these solutions were counted to evaluate the sterilization performance.
Results: In the case of mixed solution that initially has dissolved 0.5 mg/l of ozone, 3.83 ± 0.02 log CFU/ml of viable bacteria was detected. Adding triacetin to this solution, the viable bacteria was 3.56 ± 0.04 log CFU/ml, and addition of triacetin showed little effect on performance. On the other hand, in the case of micro-bubble ozone solution, viable bacteria were not detected. Because the amount of supplied ozone of micro-bubble treatment was sufficiently lower than that of mixed solution, it can be assumed that micro-bubble generation by surface-active agents enhance the sterilization performance of ozone gas.
Significance: Micro-bubble generation utilizing surface-active agents is an effective way to enhance sterilization performance of ozone.