Purpose: This study was designed to determine the efficacy of thymol, thyme oil, and baking soda against Salmonella on cucumbers.
Methods: The antimicrobial activity of thymol, thyme oil, vinegar, and baking soda was tested against a three-strain cocktail of Salmonella (Salmonella Enteritidis, S. Typhimurium, and S. Mission). A 20 µl of Salmonella cocktail suspension at 108 CFU/ml was spot-inoculated on the cucumbers and air-dried for 2 h prior to exposure to sanitizing solutions. Treatments included the following: thymol (0.2 and 0.4 mg/ml), thyme oil (1 and 2.0 mg/ml), vinegar (5% and 0.5 %), and baking soda (5% and 10%). Cucumbers were dipped in the sanitizing solutions for 1, 3 and 5 minutes.
Results: On average, washing cucumbers with thymol (0.4 mg/ml); thyme oil (2 mg/ml), and vinegar (5%) for 5 min resulted in Salmonella reduction of 3.57, 3.08 log10 CFU, respectively. Thymol (0.4 mg/ml) and thyme oil (0.2 mg/ml) were most effective (P < 0.05) sanitizing solutions, which achieved >3.0 log reductions of Salmonella after a 5-min washing. There was no significant difference (P > 0.05) in Salmonella reduction after 5-min washing in vinegar (0.5%) and baking soda (10%). Less than 1 log Salmonella reduction was achieved with 0.5% vinegar. There was no residual Salmonella in thyme washing (2.0 mg/ml), thymol (0.4 mg/ml), and vinegar (5%) solutions.
Significance: The success of this project will provide science-based information on significance of alternative treatments other than chlorine to reduce foodborne pathogens in produce, especially cucumbers.