Tomatoes have been implicated in various microbial disease outbreaks and are considered a potential vehicle for foodborne pathogens.
Traceback studies mostly implicate contamination during production and/or processing. The microbiological quality of commercially produced tomatoes was thus investigated from the farm to market, focusing on the impact of contaminated irrigation and washing water, facility sanitation, and personal hygiene.
A total of 905 samples were collected from three large-scale commercial farms from 2012 through 2014. The farms differed in water sources used (surface versus well) and production methods (open field versus tunnel). Levels of total coliforms and Escherichia coli and prevalence of E. coli O157:H7 and Salmonella Typhimurium were determined. Dominant coliforms were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. No pathogens or E. coli were detected on any of the tomatoes tested throughout the study despite the high levels of coliforms (4.2 to 6.2 log CFU/g) present on the tomatoes at the market. The dominant species associated with tomatoes belonged to the genera Enterobacter, Klebsiella, and Citrobacter. Water used on the farm for irrigation considered not fit for purpose according to national agricultural irrigation standards, with high E. coli levels resulting from either a highly contaminated source water (river water at 3.19 log most probable number [MPN]/100 ml) or improper storage of source water (stored well water at 1.72 log MPN/100 ml). Salmonella Typhimurium was detected on two occasions on a contact surface in the processing facility of the first farm in 2012. Contact surface coliform counts were 2.9 to 4.8 log CFU/cm2.
Risk areas identified in this study were water used for irrigation and poor sanitation practices in the processing facility. Implementation of effective food safety management systems in the fresh produce industry is of the utmost importance to ensure product safety for consumers.
Microbiological food safety status of commercially produced tomatoes from production to marketing
Journal of Food Protection, Number 3, March 2016, Pages 392-406, DOI: http://dx.doi.org/10.4315/0362-028X.JFP-15-300
N. van Dyk, W. de Bruin, E. M. du Plessis, and L. Korsten