Microbial Safety of Fresh Herbs from Los Angeles, Orange County, and Seattle Farmers’ Markets

Introduction: Farmers’ markets have been growing in popularity along the West Coast of the United States.  These markets are generally held during the summer months and the produce is stored in open booths at ambient temperatures.  Currently, there is a gap in knowledge regarding the microbial quality and safety of the items sold at farmers’ markets in the United States.

Purpose: The purpose of this study was to assess the microbial safety and quality of fresh basil, parsley, and cilantro sold at farmers’ markets in the Los Angeles, Orange County, and greater Seattle areas.

Methods: A total of 133 samples (52 basil, 41 cilantro, and 40 parsley) were collected from 13 different farmers’ markets and they were tested for Salmonella and generic E. coli.  The samples were tested for Salmonella using a method adapted from the Food and Drug Administration Bacteriological Analytical Manual, while levels of generic E. coli were determined using E. coli/Coliform Petrifilm plates. 

Results: Although 15 fresh herb samples were found to be suspect for Salmonella, only one parsley sample confirmed positive.  This gave parsley a 2.5% prevalence rate for Salmonella.  For generic E. coli, 21.8% of the samples showed growth on Petrifilm plates with a range of 0.70-3.15 log CFU/g.  Among the herbs tested, basil showed the highest percentage of samples with growth for generic E. coli (25.0%), followed by cilantro (22.0%), and then parsley (20.0%). Overall, these results suggest a moderate frequency of trace level fecal and environmental contamination, with a minor fraction of samples being highly contaminated, in fresh herbs sold at farmers’ markets. 

Significance: The results from this study emphasize the importance of maintaining proper storage temperatures and thoroughly washing fresh produce before consumption.