The potential for Salmonella populations to “rebound” on produce in humid conditions before and after washing bolsters the need for uninterrupted cold storage, according to research.
A study conducted by researchers at Virginia State University and Arkansas State University found that cold storage at between 4°C and 10°C effectively prevented the growth of Salmonella on both washed and non-washed produce.
The report, Salmonella Population Rebound and Its Prevention on Spray Washed and Non-washed Jalapeño Peppers and Roma Tomatoes in Humid Storage, highlighted the ability of Salmonella microbes to “rebound” on produce in humid storage before or after washing.
According to Virginia State University’s Steven Pao, who co-wrote the report, the risk of post-washing pathogen growth on produce should be considered in any overall food safety risk assessment.
Unbroken cold chain
“The report highlights the benefit of unbroken cold-chain systems from the farm to the dinner table in produce safety practices, especially under moist storage conditions,” said Pao.
“This research is relevant to the produce industry since modern packing and processing facilities often use washing and brushing procedures to achieve produce cleaning and sanitisation. We demonstrated that, irrespective of rinsing and brushing, the microbial pathogen can rebound on produce under conductive conditions.”
“Thus, the risk of post-washing growth of residual pathogens on produce should be considered in the overall risk assessment food safety management,” he said.
According to Pao, a more thorough understanding of microbial ecology and the route of contamination it needed to prevent foodborne disease outbreaks.
The study identified the risk associated with the ability of Salmonella population to rebound on “washed produce at ambient temperatures (≥21C) in humid storage.”
“This study indicated that storage temperatures at ≤10 C are adequate for preventing Salmonella population rebound, whereas leaving washed produce at ambient temperatures (≥21 C) in humid storage or ripening may erase some of the decontamination impact from prior washing.”
“Our research is aimed at generating scientific data to support decision making or technology development,” Pao said.
“The data offers an initial/practical approach for managing the post-washing food safety risk associated with pathogen rebound.”
“Our on-going produce research continues to quantatively measure/investigate the impact of washing and other intervention approaches for food safety. Guidelines and product development for both industry and/or consumers are also in consideration,” he added.
Steven Pao, Wilbert Long III, Chyer Kim, and A. Reza Rafie. Foodborne Pathogens and Disease. April 2012, 9(4): 361-366. doi:10.1089/fpd.2011.1051.