Survival of common foodborne pathogens on dates, sundried tomatoes, and dried pluots at refrigerated and ambient temperatures
2022
Canakapalli, Sushumna Sri | Sheng, Lina | Wang, Luxin
The survival of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes was assessed on low- and high-moisture Medjool dates, sundried tomatoes and dried pluots. Dates were inoculated using a dry (sand) carrier, while dried pluots and tomatoes were inoculated using a wet (phosphate-buffered saline) carrier to ensure even distribution of the inoculum on dried fruit surfaces while minimizing the impact on their physiochemical properties. Inoculated dried fruits were stored at ambient and refrigerated temperatures for 180 days. No significant change was observed in pH and water activity of dried fruits during storage. In general, pathogens survived at higher levels for longer time on dates (pH 5.59–5.83) than sundried tomatoes (pH 3.80) and pluots (pH 3.45) and better at refrigerated temperature than ambient temperature. Salmonella survived better than the other two pathogens. When inoculated on dates, up to 5.31 log CFU/g of Salmonella was recovered after 180 days of refrigerated storage. Results of this study prove that common foodborne pathogens can survive on dried fruits, particularly at refrigerated temperature. Factors such as pH, water activity, and inoculation levels impact bacterial behavior during storage. Control measures need to be validated to minimize pathogen contamination of dried fruits and ensure their microbial safety.
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