Microbial Quality of Fresh Produce: Impact of Farming Operations and Readiness for Traceability Requirement

Introduction: Fresh produce is increasingly implicated in foodborne outbreaks, like the ones recently reported with L. monocytogenes, E coli, and Salmonella spp. in cantaloupe, sprouts, and peppers, respectively.  Since agricultural practices for production of fresh produce have changed, the potential of microbial risk also has evolved and increased.

Purpose: The objectives of this study were to identify the risk of pathogenic Salmonella spp (SS). and E. coli O157:H7 (ECH) contamination on fresh produce grown using different farming practices (high tunnels and open fields) and determine the readiness of North Carolina (NC) farmers for adoption of fresh produce traceability system.

Methods: Soil and water samples were collected from 12 small-scale farms in NC and inoculated onto selective media (TSA for total aerobic count, XLT4 for SS., and MacConkey for ECH). All plates were incubated at 48 hours at 37 °C.  Following incubation, colonies were counted and the numbers were expressed as log CFU/ml. The identification of microorganisms was carried out by multiplex PCR analysis. The readiness of NC farmers for fresh produce traceability was tested using a quantitate survey on 22 farmers spread throughout the state.

Results:  The results indicated that soil samples collected from high tunnel farms had the highest microbial load (8.26 log CFU/ml on TSA, 7.8 log CFU/ml on MAC, 7.3 log CFU/ml on XLT4). Both water and soil samples collected from open-field farms, especially those located in the western part of the state, had the lowest microbial counts, indicating that humidity and temperature directly affect the microbial content of soil and irrigation water. The PCR analysis confirmed the presence of SS only in soil samples collected from a farm located in the eastern part of the state. The traceability survey results demonstrated that 85% of farmers who participated in the survey were not familiar with the produce traceability system and traceability concept/requirement. All 22 farmers wanted to be trained on produce traceability and be able to implement the system to improve the safety of their produce.

Significance: Based on these results, improvements are needed to prevent pathogenic contamination in different farming operations to enhance produce safety. The small-scale produce farmers are interested in traceability and other ways to improve product quality and safety. Hence, they should be trained on produce traceability and best practice farming operations that increase farm profitability and sustainability.