Effect of water suspended particles on the recovery of Cryptosporidium parvum from tomato surfaces

An increase in the number of outbreaks of foodborne disease associated with fresh produce consumption has been described. The objective of the present study was to evaluate the effect of water suspended particles during immersing/spraying disinfection processes and the recovery of Cryptosporidium parvum oocysts from tomato surfaces. Tomatoes (Lycopersicum esculetum Mill.) were immersed/sprayed with chlorinated water with low and high suspended particle content (10 and 1,000 mg/l) containing 100, 1,000 or 10,000 oocysts/l. Tomatoes were evaluated after a contact time of 120 seconds and 30 seconds for immersing and spraying procedures, respectively. The immersing procedure showed a high recovery of C. parvum oocysts from the tomato surface when the concentration was 10,000 oocysts/l and 10 mg/l suspended particles (295±94 [mean±standard deviation]). High particle content affected oocyst recovery and dissolved particles exerted a chlorine demand reducing the disinfectant residual. In the spraying procedure, the highest recovery was observed with 10,000 oocysts/l (225±72). Our understanding is that the association of C. parvum oocysts with suspended particles might promote the oocyst deposition in the wash water tanks and that this interaction should be considered when evaluating the quality of the water.