Prevalence, Persistence and Control Strategies of Listeria Ssp. and Salmonella in Retail Grocery Produce Storage and Sales Environments

No studies have evaluated Salmonella or Listeria prevalence in retail produce storage, handling, and sales environments. Contamination can theoretically occur at any point in the farm-to-fork pipeline; however, the relative risk of contamination at each stage has not been determined. A study of fresh produce collected prior to retail found that just 0.58% of domestic fresh produce samples were positive for Salmonella (FDA, 2003), while 3.5% of imported fresh produce tested positive for Salmonella (FDA, 2001). While no studies on produce contamination levels at retail have been conducted in the U.S., a study of produce purchased from grocery stores in Spain found no Salmonella on uncut produce, but 0.8-10% of cut produce samples contained Salmonella and 0.8-3.4% of samples tested positive for L. monocytogenes (Abadias et al., 2008), suggesting that produce may have become contaminated during processing. A study of sprouts, pre-cut fruit, and unpasteurized juices from retail in the U.K.
found no Salmonella present, but 5.2% of samples contained L. monocytogenes (Little et al., 2004). This study, however, did not compare to uncut produce, so it is impossible to determine how much contamination was present prior to processing at retail. Since even less is known about Salmonella and Listeria prevalence on U.S.-based produce and retail surfaces, this constitutes a major knowledge gap, which hinders the development of appropriate safety practices and standards. As leading experts in retail food safety research, we are positioned to conduct studies that enable regulatory agencies and the food industry to advance food safety practices, reduce the cost of foodborne illness, and improve public health. Therefore our specific objectives are to:Objective I. Elucidate Salmonella, L. monocytogenes, and other L. spp. contamination patterns and persistence in retail grocery produce storage and sales environments.Objective II. Identify practices and store characteristics that
distinguish produce storage and sales environments with low Salmonella, L. monocytogenes, and other L. spp. prevalence from stores with high prevalence and evidence of persistence.Objective III. Develop, implement, and test practical and feasible control strategies in select establishments to (i) reduce Salmonella and L. monocytogenes in retail produce environments and (ii) reduce cross-contamination.Our long-term goal is to foundational data that will (i) assist in the identification of food safety hazards in produce at retail, (ii) elucidate effective and practice mitigation strategies to control L. monocytogenes and Salmonella in retail produce environments, and (iii) provide evidence needed to conduct further root-cause-analysis. Such analysis would identify factors and practices that contribute to increased foodborne pathogens in food handling environments beyond sanitation standard operating procedures (SSOPs) (e.g., investigate impact of food safety culture, training, and
business practices).