Antibacterial Mechanism and Flavour Impact of Ultrasound and Plasma-Activated Water Combination on Aeromonas veronii in Crayfish

<i>Aeromonas veronii</i> is a foodborne pathogen commonly found in contaminated crayfish. In this study, the effects of ultrasound combined with plasma-activated water (US-PAW) against <i>A. veronii</i> and on the flavour of crayfish were investigated to evaluate their impact on crayfish preservation. In vitro, US and PAW showed a significantly synergistic inhibition against <i>A. veronii</i> growth and biofilm reformation at 7 min. Furthermore, PAW disrupted the membrane integrity of <i>A. veronii</i>, accompanied by enhanced outer membrane permeability, with bacteria exhibiting distortion, deformation, and the accelerated leakage of intracellular substances, which US-PAW further promoted. Additionally, US-PAW increased the intracellular levels of reactive oxygen species and hydrogen peroxide, disrupting cellular homeostasis. This resulted in a significant decrease in the activities of SOD and GSH, as well as a reduction in the intracellular ATP concentration and the activities of MDH and SDH. The results indicated that US-PAW treatment impairs the ability of <i>A. veronii</i> cells to generate sufficient energy to resist external stress, ultimately leading to bacterial death due to the inability to maintain normal physiological functions. According to the bacterial cell count and GC-MS analysed, US-PAW treatment increased the storage period of crayfish (infected with <i>A. veronii</i>) by 2 days, while reducing sulphur-containing volatiles within 24.64% during 6 days of storage at 4 °C. These conclusions provide a theoretical foundation for the industrial application of US-PAW to preserve crayfish.