Characterization of Air and Ozone Micro‐Nano Bubbles and Their Impacts on Physicochemical Attributes, Total Phenolic Content, and Natural Microbial Load of Fresh “Fan Retief” Guava During Storage

ABSTRACT Chlorine‐based water treatment for fresh produce has diverse limitations including the production of disinfectant‐by‐product residue. Thus, this study characterized and investigated the impact of micro‐nano bubble (MNB) water (air and ozone (O 3 )) on the quality attributes of guava fruit during storage. Air‐ or O 3 ‐MNB were loaded on Malvern Panalytical NnanoSight NS300 and Zetasizer Nano ZS for characterization. Thereafter, batches of guavas were immersed for 30 min in air‐ or O 3 ‐MNB and others in sodium hypochlorite (NaOCl) or sterile tap water (control) and stored for 21 days at 13°C with 90 ± 2%, relative humidity. The results indicated that zeta‐potential, electrical conductivity, and oxidation reduction potential of O 3 ‐MNB were significantly higher than that of air‐MNB ( p ≤ 0.05). Both air‐ and O 3 ‐MNB delayed the decrease in lightness ( L *), and significantly maintained low titratable acidity, total soluble solids, and microbial load compared to control ( p < 0.001). Higher changes in fruit TSS/TA and total color difference were associated with control samples, followed by NaOCl treated samples. O 3 ‐MNB significantly slowed down physiological response compared to control ( p < 0.05). Practical Applications This study successfully characterized micro‐nano bubble waters and offered a paradigm shift from chlorine‐based sanitizers to micro‐nano bubble waters as a promising technology to maintain quality, enhance bioactive compounds, and delay fruit decay.