Behaviour of Listeria monocytogenes and Yersinia enterocolitica during beef dry-aging up to 60 days

The Commission delegated Regulation (EU) 2024/1141 states that beef dry aging can be performed in a dedicated cabinet, at a surface temperature of -0.5 to 3 °C, maximum relative humidity of 85 %, air speed of 0.2-0.5 m/s and for a maximum of 35 days. Food business operators can apply different process parameters, even longer aging times, as long as they demonstrate to the competent authority that the aged meat is microbiologically safe. To support food business operators in the implementation of longer dry aging processes, in this study we investigated the behaviour of Listeria monocytogenes and Yersinia enterocolitica during beef dry aging in a patented cabinet up to 60 days. Beef loins were experimentally spiked with a mean load of 4.4 and 3.9 Log10 CFU/g of Listeria monocytogenes and Yersinia enterocolitica respectively and stored at 1 °C, relative humidity 78 % and ventilation 2.0 m/s for 60 days. L. monocytogenes counts did not significantly change during the dry aging process, while Y. enterocolitica significantly increased up to 3 Log10 CFU/g during the aging process and then tended to decrease at 60 days. The results of this study showed that beef dry aging at 1 ± 2 °C, relative humidity 78 ± 7 %, ventilation 2.0 m/s for 60 days does not support the growth of L. monocytogenes. On the contrary, the same process supported the growth of Y. enterocolitica up to 40 days in two of the three tested batches, showing that the impact of dry aging on the behaviour of this pathogen deserves further studies.