Laboratory re-enactment of storage practices of older adults to determine potential implications for growth of listeria monocytogenes

Older adults are particularly susceptible to listeriosis, and many frequently consume ready-to-eat (RTE) foods associated with Listeria monocytogenes. Consequently, safe storage of RTE-food is essential to reduce the risks of listeriosis. This study aimed to re-enact domestic food-storage malpractices of older adult consumers in a laboratory, to assess the potential impact on L. mono-cytogenes. Observed and self-reported data relating to domestic food-storage malpractices included prolonged storage of RTE foods and/or refrigeration temperatures exceeding recommendations (> 5.0°C). Re-enactment was performed using soft-cheese and RTE meat inoculated with ~3.7 log CFU L. monocytogenes, stored at recom-mended temperatures (2.5°C) (n = 110); temperatures exceeding recommendations (7.8°C) (n = 110), and ambient temperature (19.5°C) (n = 55). Samples were analyzed every 24 h for up to 21 days. Results indicated that L. monocytogenes grew at all storage temperatures. Average generation times indicated slower growth of L. monocytogenes at 2.5°C (94 h t^-1) than at either 7.8°C (21.5 h t^-1) or 19.5°C (11 h t^-1), suggesting that prolonged storage of RTE foods resulted in increased L. monocyto-genes populations (< 7.6 log CFU/g), potentially making such foods unsafe for consumption. Findings indicate that storage practices contrary to consumer recommend-ations, which are intended to reduce the risk of foodborne disease, increase L. monocytogenes populations, thus increasing the potential for foodborne disease.