Evaluation of growth potential and growth dynamics of Listeria monocytogenes on ready-to-eat fresh fruit

The consumption of fresh or RTE fruits is increasing every year and Listeria monocytogenes has been identified on raw or minimally processed fruits. A food product can become contaminated with L. monocytogenes anywhere along the pathway of food production during planting, harvesting, packaging, distribution and serving. The aim of this work was to assess the microbiological risks associated with consumption of ready-to-eat fruit such as melon, pineapple, coconut and fruit salad. The presence of Escherichia coli, Salmonella spp. and L. monocytogenes was also evaluated. Microbiological challenge tests were carried out for the evaluation of the L. monocytogenes growth potential in RTE fruit stored at 4 and 8°C. E. coli counts resulted under the detection limit of 10 CFU g-1, Salmonella and L. monocytogenes were not detected (absence in 25g). The growth potential values in coconut and melon (δ>0.5) showed the growth capacity of Listeria at the temperatures considered. A low initial load, also derived from good hygiene practices, and correct storage temperatures are essential to reduce bacterial growth in RTE fruit. The challenge test showed how each type of RTE fruit has a different commercial life based on its specific growth potential and that food should be stored at temperatures not higher than 4°C for a short period.