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The evaluation of the microbial safety of fresh ready-to-eat vegetables produced by different technologies in Italy

De Giusti, M., Aurigemma, C., Marinelli, L., Tufi, D., De Medici, D., Di Pasquale, S., De Vito, C., Boccia, A.
Journal of applied microbiology 2010 v.109 no.3 pp. 996-1006
Escherichia coli O157, HACCP, Hepatitis A virus, Listeria monocytogenes, Norovirus, Salmonella, chlorine, compliance, disinfection, guanosine monophosphate, microbiological quality, packaging, pathogens, polymerase chain reaction, production technology, quality control, ready-to-eat foods, salads, vegetables, washing, Italy
The study was performed to evaluate the safety of whole and RTE vegetables and to investigate the effectiveness of different preventive strategies for the quality assurance of RTE vegetables collected from three Italian production systems. Producer 1, applied a strict system in compliance with GAP- GMP - HACCP, Producer 2 used chlorine disinfection at a second washing step, and Producer 3 using a physical microbial stabilization. During the period 2005-2007, a total of 964 samples including whole vegetables and RTE salads, collected from three different producers in central Italy, were analysed to quantify the aerobic mesophilic count (AMC) and Escherichia coli, and for the presence of Salmonella spp, Listeria monocytogenes, E. coli O157:H7, hepatitis A virus and Norovirus (NoV). None of the whole vegetable samples were positive for L. monocytogenes, E. coli O157:H7, HAV and NoV; however, a low prevalence of Salmonella was found. No pathogens were detected with cultural methods in any of the RTE vegetables analysed, only two RTE samples were positive for L. monocytogenes with PCR, but were not confirmed by the cultural method. The median values of AMC in RTE vegetables measured 24 h after packaging were statistically different among the 3 producers (5·4 x 10⁶, 1·5 x 10⁷ and 3·7 x 10⁷ CFU g⁻¹, respectively; P = 0·011). The lowest level was detected in Producer 1. The products that were processed applying rigorously GAP, GMP and HACCP showed a better microbiological quality than those processed with chemical or physical stabilization. The results of the study evidenced the efficacy of GAP, GMP and HACCP in improving microbiological quality of whole and RTE vegetables.