Risk Factors for Microbiological Contamination of Produce: A Field Study of Domestic and Imported Produce in Packing Sheds

Specific aims: <OL> <LI> Describe processing practices used by packing sheds in the Lower Rio Grande Valley for 5 susceptible produce groups/items that are consumed raw (cabbage, green onions, cilantro/basil/parsley, arugula/spinach/leaf lettuce, melons/cantaloupe) by interviews with packing shed managers; <LI> Identify specific, critical processing practices where contamination with foodborne pathogens and fecal indicators is likely by conducting sanitary surveys, and measuring the microbial quality of produce at each step in the process from receipt at the packing sheds through washing, rinsing, and packaging to shipping. Determine sources of contamination by measuring a)general microbiological quality, microbial indicators of fecal contamination and key foodborne pathogens in samples of the incoming product, final product and the product after each processing step; b)microbial indicators of fecal contamination in water used at each processing step; c) fecal indicator organisms in hand rinses from food handlers in the sheds;<LI>ldentify correlations between the production site and specific processing/handling practices and the levels of microbial indicators of food quality/safety.
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Over two growing seasons, the study will measure: <OL> <LI> Characteristics of the packing sheds, including water supply and treatment, wastewater disposal practices, sanitation facilities and personal hygiene habits of workers; <LI> The microbiological quality of water used at each stage of processing in the packing/shipping facility will be analyzed for fecal coliforms, E. coil, C. perfringens and somatic and male-specific coliphages; <LI> The personal hygiene of produce handlers will be assessed by testing for fecal coliforms and E. coli in hand rinse samples from farm workers and workers in the packing facility; <LI> The microbiological quality of produce samples from each stage of processing,packing and shipping. Samples will be collected and tested for total aerobic mesophiles, total coliforms, fecal coliforms, E. Coli, total enterococci, Salmonella, E. coil 0157:H7, Shigella and Listeria monocytogenes.
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Recently, new and emerging foodborne pathogens have been described and changes in food production have led to new food safety concerns. Foodborne diseases have been associated with contaminated fresh fruits and vegetables. Preliminary data suggest that some produce may become contaminated in packing sheds. This study will examine how specific produce processing practices are associated with fecal contamination of selected produce groups and will compare the microbiological quality of domestic and Mexican produce before, during and after processing. This study will describe packing and shipping practices in approximately 20 packing sheds for vulnerable produce groups that are minimally processed and eaten raw (leaf lettuce/spinach, parsley/cilantro/basil, green onions, cabbage, melons/cantaloupe). Key practices where contamination may occur will be identified by measuring the microbial quality of produce samples collected at each step during the packing process. Sources of fecal contamination will be determined by periodically measuring microbial quality of samples of shed process water and hand rinses from shed handlers. The information gained through this study will be used to design effective measures to reduce produce contamination during processing and packing and subsequently reduce foodborne disease.