Inactivation of Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes on cherry tomatoes and oranges by superheated steam.

This study was performed to compare the effectiveness of saturated steam and superheated steam for the inactivation of Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes on the surface of cherry tomatoes and oranges. It also determined the effect of the steam processes on the color, texture, Vitamin C content, and antioxidant capacity and changes in these parameters during chilled storage. Cherry tomatoes and oranges inoculated with the three foodborne pathogens were treated with saturated steam at 100 °C and superheated steam at 125, 150, 175, and 200 °C for various time intervals. After the cherry tomatoes and oranges were exposed to superheated steam at 200 °C for 3 or 20 s, all tested pathogens were reduced to below the detection limit (1 or 1.7 log, respectively) without significant changes in color, texture, vitamin C content, and antioxidant capacity (P > .05) at 4 °C for up to 9 days. Our results suggest that superheated steam treatment can be effective at decreasing pathogen populations when compared to saturated steam, without significant quality deterioration, and thus, this technique demonstrates great potential to improve the microbial safety of fresh produce.