Purpose: The purpose of this study was to evaluate the survival capability of Salmonella on mini cucumbers.
Methods: Five strains of Salmonella enterica were inoculated onto mini cucumbers and subsequently incubated at 20°C for 8 days or at 4°C for 19 days respectively, to identify survival characteristics and capabilities. Three strains were isolated from irrigation water in Lower Mainland British Columbia, Canada (Salmonella Typhimurium, Salmonella Enteritidis, Salmonella Daytona). The other two were Salmonella Newport (FSL S5-639, a clinical isolate) and Salmonella Poona (S306). The survival of individual Salmonella strains was monitored using the one-step thin agar layer method.
Results: Overall, S. enterica was able to survive on cucumbers at both temperatures for an extended period of up to 8 or 19 days. Different S. enterica strains showed differential survival rates at both temperatures.
At 20°C, Salmonella Poona was identified to possess the strongest survival capability with the highest area under survival curve (AUC) of 50.74±0.431 days by log CFU, while the survival of Salmonella Typhimurium, Salmonella Enteritidis, Salmonella Daytona, and Salmonella Newport all showed a slight decline. At 4°C Salmonella Enteritidis exhibited the strongest survival capability and there was an evident recovery of growth from the initial sharp decrease for all the other strains.
Significance: These results suggest that Salmonella can survive on cucumbers at room temperature and refrigeration. Unique survival characteristics among Salmonella strains at different temperatures increase our understanding of the factors influencing microbial safety of fresh produce and reveal that corresponding interventions need to be applied to eliminate contamination of produce with specific Salmonella.