P2-79 Microbial Quality of Leafy Greens and Herbs Purchased from Farmers’ Markets in Virginia and North Carolina

Tuesday, August 2, 2016
America's Center - St. Louis
John di Stefano, Virginia Tech, Blacksburg, VA
Renee Boyer, Virginia Tech, Blacksburg, VA
Minh Duong, Virginia Tech, Blacksburg, VA
Benjamin Chapman, North Carolina State University, Raleigh, NC
Monica Ponder, Virginia Tech, Blacksburg, VA
Laura Strawn, Virginia Tech, Painter, VA
Introduction: The number of registered farmer’s markets has nearly tripled in the last 15 years. Fresh produce accounts for over 80% of the food sold at these markets. Previous work shows that leafy greens and herbs tend to have a higher microbial load amongst fresh produce commodities. 

Purpose: The purpose of this study was to assess microbial quality of different leafy green and herb varieties sold at farmers’ markets in Virginia and North Carolina.

Methods: Fourteen different varieties of leafy green and herb samples (n=256) were collected from NC and VA farmers’ markets between June and October. Each sample was tested for total aerobic plate count (APC), coliforms, generic E. coli and Enterococci using 3M Petrifilm and KF Streptococcal agar. To detect pathogens, samples were enriched in selective media and T-streaked onto selective agar to identify presumptive positives colonies. 

Results: Arugula and salad mix were highest in all counts, including coliform (3.97 and 4.39 CFU/g), E. coli (0.27 and 0.20 CFU/g) and Enterococci counts (3.79 and 3.41 CFU/g). Cilantro had the highest APC count of all varietals (7.70 log CFU/g), while romaine lettuce and basil had the lowest (6.25 and 6.22 log CFU/g, respectively). Varieties with no detectable E. coli were butter head lettuce, red leaf lettuce, purslane, cilantro and basil. Enterococci counts were highest in red leaf lettuce and cilantro (4.13 and 3.74 log CFU/g, respectively) and lowest in butter head lettuce and basil (2.88 and 2.60 log CFU/g, respectively). There were generally no differences in microbial counts associated with vendor where product was purchased.

Significance: While leafy greens and herbs inherently contain high microbial loads, the results suggest that certain varietals may be at higher risk for contamination. Specific handling practices may contribute to this risk.