Inactivation effect of Staphylococcus aureus and application on fresh-cut pineapples by plasma-activated tartaric acid

The insufficient antibacterial effect of organic acids accelerates the desire for new decontamination approaches. This study aimed to investigate the combined inactivation efficacy of plasma-activated water (PAW) and organic acids on Staphylococcus aureus (S. aureus) as well as the underlying mechanism. The present study showed that the PAW or tartaric acid (TA) treatment led to an approximately 1 log CFU/mL decrease of S. aureus cells, while a higher reduction of 5.42 log CFU/mL was observed after the combined treatment (PAW plus TA). Scanning electron microscope and propidium iodide staining analysis showed that the structure and activity of most bacteria were not changed. The PAW and TA treatments caused modest oxidative damage to the cell membrane, while the damage to defense function occurred in S. aureus after the combined treatment, as indicated by the lower ROS level and higher MDA content compared with the control. Meanwhile, the combined treatment caused 2.7 and 4.1 log CFU/g reductions of S. aureus cells in a fresh-cut pineapple model at 4 °C and 25 °C. This approach could maintain most quality attributes of fresh-cut pineapples at an acceptable level and extend their shelf life. The results suggest that the combination of PAW and TA could be considered a novel technology for bacterial inactivation in fresh-cut products.