Evaluation of Microbial Contamination of Tomatoes and Peppers at Retail Markets in Monterrey, Mexico

Abstract

The source of a large outbreak of foodborne disease related to Salmonella-contaminated jalapeño peppers has been traced to Nuevo Leon, Mexico. The objective of this work was to evaluate the microbiological quality of tomatoes and jalapeño peppers from markets and supermarkets from the metropolitan area of Monterrey, Nuevo León, Mexico. One hundred sixty samples (40 bola tomatoes, 40 saladette [Roma] tomatoes, 40 serrano peppers, and 40 jalapeño peppers) were purchased. Stems from peppers were removed and analyzed separately. Samples were analyzed for indicator organisms and Salmonella, following the Mexican Official Methods. The results showed that the presence of indicator organisms varied among samples and origins, and levels were relatively high in peppers (average 4.4 to 4.7 log CFU/g for total mesophilic, 3.25 to 3.73 log CFU/g for total coliforms, and 1.69 log CFU/g for fecal coliforms). Saladette tomatoes and serrano peppers showed the greatest microorganism levels (~1 log CFU/g higher) in comparison with the other varieties. Pepper stems typically had indicator microbial levels ~1 to 2 log CFU/g higher than levels in smooth flesh. Only one tomato and one jalapeño sample were positive for Salmonella. However, in the case of the pepper, the contamination was found in the stem. Although the microbiological quality of tomatoes and peppers sampled was similar to that found in markets from developed countries, the presence of pathogens causes a risk of infection for consumers.