Microbial Profiles of Selected Fresh Produce from Farmers’ Markets and Retail Stores in Illinois

Introduction: Consumer demand for fresh produce and proximity of produce that can be marketed in the local markets without major quality losses are critical factors contributing to the rapid increase of farmers’ markets in last decades in U.S.A. However, there has been no documented study assessing the microbial safety risk of locally-grown produce in comparison with produce from major supply chains sold in grocery stores. 

Purpose: The purpose of this study is to assess and compare the microbial profiles of three fresh vegetables from farmers’ markets and retail stores.

Methods: Seventy-two farm stands in 28 farmers’ markets in Illinois were randomly selected for sample collection.  Eleven retail stores in Illinois were chosen for comparing the microbial loads. The samples were collected from June, 2013, to October, 2013. The three vegetables included lettuces (n = 43), pepper (n = 64) and tomatoes (n = 68). APC, generic E. coli and coliform counts were determined using 3M™ Petri film. Salmonella sp. and E. coli O157:H7 were analyzed by FDA BAM.

Results: No Salmonella spp. and E. coli O157:H7 were detected.  APC and coliform of pepper (4.61 and 1.35 mean log CFU/g) and tomato (4.18 and 1.19 mean log CFU/g) from the farmers’ markets were not significantly different from those of pepper (4.32 and 1.62 mean CFU/g) and tomato (3.7 and 0.69 mean CFU/g) from the retail stores. However, APC and coliform of lettuce from the farmers’ markets were significantly different from those from the grocery stores.  Percent E. coli positive in lettuce (13.64%), pepper (7.14%), and tomato (2.17%) from the farmers’ markets were little higher than those (9.52, 4.76 and 0 %) of retail markets. There were no significant differences between coliform and aerobic plate counts when analyzed by farmers’ market size, location, and sampling time.

Significance: The data collected provided useful information for determining food safety issues of locally grown produce and development of food safety training materials for produce farmers.