Formation of ozone ice by freezing water containing ozone micro-bubbles (Investigation into the influence of surfactant on characteristics of ice containing oxygen micro-bubbles)

Recently, the use of ice containing trapped gaseous ozone, which provides the dual benefits of sterilization and deodorization, has gathered increased attention as a food cold storage method. As a method of efficiently trapping gaseous ozone in ice, the authors previously proposed the use of micro-bubbles with several tens of micro-meters in size. Since the process used to trap ozone micro-bubbles results in both ozone gas bubbles and dissolved ozone in the ice itself, both forms of ozone can be recovered and used effectively when the ice is melted. In this study, as the first step, gaseous oxygen is substituted for ozone, after which the suppression of oxygen micro-bubble coalescence, and decrease in the lifting speed of the bubbles caused by adding a small amount of surfactant, are investigated. Additionally, the influence of added surfactant on distribution of bubble size in ice, ice formation rate, mass of formed ice, and bubble content in ice are clarified.

► Decrease in bubbles diameters in water due to surfactant was clarified. ► There were no enlarged bubbles on cooling surface when surfactant was added. ► Surfactant realized smaller and even distribution of bubbles diameters in ice. ► Increases in bubble content in ice and mass of ice due to surfactant were clarified. ► The range of the optimal cooling plate inclination could be spread by surfactant.