Growth and survival of Salmonella enterica and Listeria monocytogenes on fresh-cut produce and their juice extracts: Impacts and interactions of food matrices and temperature abuse conditions

Abstract

Storage temperature and nutrient availability are major factors impacting pathogen growth and thus food safety risks. This study evaluated the survival and growth of Salmonella enterica, and Listeria monocytogenes in relation to temperature abuse variations, and food matrices. Fresh-cut cantaloupe, honeydew, watermelon, pineapple, and radish contaminated with S. enterica and L. monocytogenes were subjected to cold (4 °C), chronic temperature abuse at 8 and 12 °C, and acute temperature abuse (35 °C for 2 h followed by 4 °C for the remainder 7-day storage). Pathogen growth potential in the juice extracts from each product was further compared to that on the respective cut produce. Under chronic temperature abuse, three different pathogen growth patterns emerged on five test products: both S. enterica and L. monocytogenes grew significantly on cut cantaloupe, honeydew and watermelon at 8 and 12 °C; but only survived on cut radish, and even declined in population on cut pineapple under the same conditions. Specifically, S. enterica populations reached up to 5.28 log CFU/g and L. monocytogenes up to 7.77 log CFU/g after 7 days at 12 °C. During cold storage at 4 °C, significantly different growth patterns were also observed between S. enterica and L. monocytogenes on cut melons, where S. enterica populations remained unchanged during the 7-day storage while L. monocytogenes grew continuously. In the juice extracts, S. enterica and L. monocytogenes reached maximum population density in melon juices, but failed to grow in pineapple juice, similar to the growth patterns on cut melon and pineapple. Distinctly different growth patterns, however, were shown in S. enterica and L. monocytogenes on cut radish and in radish juice; exhibiting no growth on cut radish, but maximum growth in radish juice. The disparity in pathogen growth observed on cut pineapple and radish versus on melon in this study supports commodity specific risk-based food safety policies pertaining to temperature control for food safety.