Microbiological Quality of Ready-to-eat Salads from Processing Plant to the Consumers

This study aimed to assess the microbiological quality of ready-to-eat salads (Aerobic Colony Count, E. coli, yeasts and moulds, S. aureus, Salmonella spp., L. monocytogenes, C. perfringens) and the effect of temperature abuse on the microbial count. Ready-to-eat salads samples were produced and commercialized in Italy and sampled, from January 2017 to January 2018, both at different steps of the production process in an industry (n = 300) and in different supermarkets (n = 270). The pathogenic foodborne microorganisms Salmonella spp., Listeria monocytogenes, S. aureus and Clostridium spp. were not detected and only 2.98% of the 570 samples were contaminated by E. coli, a good hygiene indicator of fecal contamination. Ready-to-eat salads samples from the industry were less contaminated, both in percentage and concentration, than the supermarket ones, particularly due to high Aerobic Colony Count values: on the day of collection, 80% samples from the industry were satisfactory, opposed to 8.3% from the retailers; at the end of shelf life, 20% samples from the industry were unsatisfactory, opposed to 80% from the retailers. Although washing salads before consumption is not effective to eliminate pathogens internalized within the plant’s tissues, our results showed that it was useful in reducing the microbiological load, especially E. coli count. This study revealed that high microbial content in retail ready-to-eat salads samples was principally due to microbial multiplication occurring during storage and transportation from industry to retailers and then at home. More frequent monitoring of storage and transport temperatures would be necessary to ensure the required hygienic quality, as well as it should be clear the writing on the packaging that “products must be kept at a maximum temperature of 8°C”.