(70f) Parametric Study on Physicochemical Properties of Ozone Microbubble - Applications to Fresh Produce Washing

To overcome the adverse effects of unhealthy and environmentally unfriendly by-products from conventional washing agents for fresh produce, ozone has been used as a sustainable technology. Although ozone is a powerful oxidant that has a strong biocidal effect and decomposes to harmless oxygen, its application is limited. This is because ozone is highly unstable, reactive with low solubility in water, which makes it difficult to control its concentration during the processing. Microbubble technology has the potential to enhance the washing efficacy because of its unique physicochemical properties such as extended stability, enhanced mass transfer rate of gas dissolution, and promotion of hydroxyl radical generation. Therefore, ozone microbubble technology has been suggested to be an effective method for fresh produce that not only enhances the safety and quality of the fresh produce but also provides a sustainable alternative for humans and environment.

The biocidal effect by combining both microbubble and ozone largely depends on its unique physicochemical properties. However, very little is known about the influence of washing processing conditions on physicochemical properties. Here, we provide a systematic study on the influence of various washing processing conditions including bubble generation methods, fluid to gas ratio, pH level, temperature, ozone concentration, and organic compound load. We focus on those physicochemical properties that are relevant to the washing efficacy including bubble size distribution, number density, mass transfer rate, stability, zeta-potential, oxidation reduction potential. The large sets of experiments allow us to develop a data-driven model that will provide a better prediction and optimization of the system. Furthermore, this model can be used as a critical tool for a broad spectrum of applications using ozone microbubbles.