Decrease of Salmonella and Escherichia coli O157:H7 counts during dry-aging of beef but potential growth of Listeria monocytogenes under certain dry-aging conditions

• Published in: Food microbiology 2022-06, Vol.104, p.104000-104000, Article 104000
• Main Authors: Van Damme, I., Varalakshmi, S., De Zutter, L., Vossen, E., De Smet, S.
• Format: Article
• Language: English
• Subjects: Animals; Cattle; Colony Count, Microbial; Dry aging; Escherichia coli O157; Food Microbiology; Food safety; Listeria; Listeria monocytogenes; Meat; Process hygiene; Salmonella; STEC
• ISSN: 0740-0020; 1095-9998
• DOI: 10.1016/j.fm.2022.104000

Dry-aging of beef comprises the storage of carcasses and (sub)primal cuts at a low temperature and relative humidity for a prolonged period, aiming to increase the sensory quality of meat. Limited data are available on the survival and potential growth of pathogens on the surface of beef during dry-aging. Therefore, this study evaluates the changes in Salmonella, Shiga toxin-producing Escherichia coli O157:H7 and Listeria monocytogenes counts during dry-aging. A mixture of pathogenic strains was inoculated on the surface of beef loins, which were stored under four different process conditions (2 °C and 6 °C × relative humidity 75 and 85% during 42 days). Salmonella and E. coli O157:H7 counts significantly decreased during dry-aging. The daily reductions varied from −0.07 to −0.14 log10 CFU and from −0.09 to −0.14 log10 CFU, respectively, depending on the loin, matrix and condition. The reduction of L. monocytogenes was slower, with a maximum of −0.07 log10 CFU/day. L. monocytogenes counts increased with 1.0 log10 CFU on the lean meat of one loin with pH > 6.0 at the end of dry-aging, indicating that this pathogen can potentially grow under certain dry-aging conditions. •Loins were dry-aged at 2 or 6 °C and relative humidity of 75 or 85% up to 42 days.•The reductions of Salmonella varied from −0.07 to −0.14 log10 CFU/day.•The reductions of Escherichia coli O157:H7 varied from −0.09 to −0.14 log10 CFU/day.•The maximum reduction of Listeria monocytogenes was −0.07 log10 CFU/day.•L. monocytogenes can potentially growth under certain dry-aging conditions.