Effect of atmospheric cold plasma (ACP) with its extended storage on the inactivation of Escherichia coli inoculated on tomato.

The study investigated the efficacy of atmospheric cold plasma (ACP) treatment on inactivation of E. coli load during extended storage period of 48h at both the temperatures of refrigeration (4°C) as well as room (25°C). The tomato samples were spot inoculated with E. coli and exposed to ACP at 15 and 60kV for 5, 10, 15, and 30min followed by their storage at 4°C and 25°C. The highest log reduction of 6logCFUmL-1 was achieved in population of E. coli after 15min of ACP treatment at 60kV, which was sustained up to storage duration of 48h at both the temperatures. Furthermore, significant reduction in E. coli was found at plasma treatment of 60kV in comparison to 15kV. The inactivation of E. coli was significantly (p<0.01) affected by combination of treatment higher voltage at extended treatment time, however, treatment time with prolonged storage of sealed ACP treated tomato was observed as a key factor in reduction of E. coli. In addition, investigation of E. coli exposed tomato surface was done using scanning electron microscopy that clearly showed the breakdown of cell cover of E. coli as a consequence of ACP. The study predicts the promising potential of the technique in sanitization of vegetables that are eaten raw like tomato.