Microbiological quality and incidence of salmonella on cherry tomatoes at retail in Querétaro, México

Abstract

Multiple outbreaks related to Salmonella in tomatoes require an evaluation of the risk associated with cherry tomatoes due to the increase in its production, consumption, and marketing in Mexico's central region. The purpose of this study was to determine the microbial quality of cherry tomatoes obtained from two retail sale points (supermarkets and local markets). Cherry tomato samples (333) were collected from four supermarkets and from four local markets, and the contents of aerobic plate count, molds and yeasts, total coliforms, and Escherichia coli were quantified; the presence of Salmonella was simultaneously determined. The median values of the microbial populations were obtained, and the data were analyzed per the sampling site by using the Wilcoxon and Kruskal-Wallis tests. The median of aerobic plate count content in tomatoes obtained from supermarkets ranged between 2.2 and 4.4 log CFU/g, and in markets from 2.9 to 4.8 log CFU/g. For molds and yeasts, the tomatoes from supermarkets (2.0 to 4.1 log CFU/g) and markets (1.5 to 4.5 log CFU/g) showed similar contents. Regardless of the sampling site, the values of total coliforms were very low, ranging from 1.0 to 1.8 log CFU/g. E. coli was detected in 5.4 and 20.1% of samples from supermarkets and markets, respectively; in both sites, the content was low (0.3 to 5.8 most probable number per g). The incidence of Salmonella was 14.1% in supermarkets and 7.8% in local markets. The results obtained from this investigation highlight the elevated risk for consumer health associated with the ingestion of cherry tomatoes.