Review on formation of cold plasma activated water (PAW) and the applications in food and agriculture

Climate change increases the need for effective and sustainable technologies in food and agriculture. Plasma-activated water (PAW) emerges as a green and sustainable technology in food processing and production. Synergy of a myriad of reactive oxygen and nitrogen species (RNOS) in PAW contributes to desirable properties of PAW. Compared to conventional methods, PAW is fast and effective for various products, not limited by the volume or shape of the treated samples. In this review, we will first introduce the fundamentals on plasma generation, physicochemical properties and characterization of PAW. Among various approaches for activation improvement, we highlight a recent progress in improving the cold plasma activation by microbubbles. Then we critically review the treatment conditions by PAW, and effectiveness of PAW for bio-film removal, food processing, plant growth in agriculture, and environment. As the research output on PAW is expanding exponentially, this review focuses on the work published within the last two years (2020-2021) to summarize the current understanding of the principles of the effects from PAW and to reflect potentials of PAW in applications for the food science and technology.