Influence of fruit matrix and storage temperature on the survival of Listeria monocytogenes in a gastrointestinal simulation

This study aimed to assess the effect of storage temperature and fruit matrix on the survival of L. monocytogenes after a gastrointestinal simulation. The growth of L. monocytogenes on different matrices (fresh-cut pear and melon and synthetic growth medium as a control) and storage temperature (1, 5, 10 and 20 C) was evaluated. Subsequently, the ability of the pathogen on different fruit matrices to overcome the gastrointestinal simulation was evaluated. The highest reduction in the population of L. monocytogenes on fresh-cut pear and melon subjected to the gastrointestinal simulation was after 6 days of storage at 5 C (0.84 and 2.12 log reduction on the pear and melon, respectively). Conversely, higher survival ratios of L. monocytogenes in both matrices were observed at 1 C, even with logarithmic increases after the whole gastrointestinal simulation during the experiment. At 20 C, the survival capacity of L. monocytogenes was higher than that under storage at 5 and 10 C when grown on fresh-cut pear, whereas this was not observed on fresh-cut melon. In general, under the proper storage temperature of fresh-cut fruit (5 C) and after 1 day of storage, the L. monocytogenes on the melon was more sensitive than that on the pear, and this behaviour was maintained for up to 9 days. The ability of L. monocytogenes to overcome the gastrointestinal tract was not enhanced when the pathogen grew on fresh-cut pear and melon under the proper storage temperature.

The authors are grateful to the University of Lleida, Grupo Alimentario Citrus and Banco Santander for Pilar Colás Medà PhD grant (UdL-Impuls Program), the Spanish Government (Ministerio de Economia y Competitividad) (research project AGL-2012-38671) and the European Regional Development Fund (FEDER) for their financial support.