Purpose: The aim of this work is to evaluate (1) the survival of Y. enterocolitica along the entire shelf life of fresh leafy vegetables and “Ready-to-Eat” (RTE) vegetables, and (2) the effectiveness of different washing treatments to reduce contamination of Yersinia enterocolitica on the surface of leafy vegetables.
Methods: Leafy vegetables were spiked with different concentration of pathogenic Yersinia enterocolitica (bio-serotypes O:3/4), stored at refrigerator temperature for six days and daily analyzed. Other spiked leafy vegetables were submitted to different domestic washing treatments (water, sodium hypochlorite at 60 and 220 ppm). All the samples were analyzed using both ISO 10273 standard cultural method and real-time PCR method.
Results: The results demonstrated that the concentration of Yersinia enterocolitica, detected on the surface of vegetables, does not decrease even when they were stored at refrigerator temperature for a week. Only the washing with 220 ppm of sodium hypochlorite can guarantee the 1-logarithm reduction of the original contamination of Y. enterocolitica in the vegetables.
Significance: Yersinia enterocolitica could persist in the vegetables for the entire shelf life and its presence could not be completely eliminated using domestic or industrial washing practices. The application of good agricultural practices and HACCP system, also in primary production, are the only measures to reduce or eliminate biological contaminants and achieve the objective of food safety in RTE vegetables.
Acknowledgment: This work was supported by the National project “Ricerca Finalizzata 2009 (RF-2009-1538880)”