Microbiological safety of aged meat.

Area of Science:

• Food Microbiology
• Meat Science
• Food Safety

Background:

• Meat ageing processes, including dry-ageing of beef and wet-ageing of beef, pork, and lamb, influence microbiological hazards and spoilage bacteria.
• Distinguishing between 'standard fresh' and wet-aged meat is crucial due to similar processing methods, differing primarily in duration.
• Understanding the impact of ageing parameters like time, temperature, pH, and water activity (a_w) is vital for meat safety.

Purpose of the Study:

• To assess the impact of dry-ageing and wet-ageing on microbiological hazards and spoilage bacteria in beef, pork, and lamb.
• To describe current meat ageing practices and their microbiological implications.
• To establish controlled ageing conditions that ensure microbial safety equivalent to or better than standard fresh meat preparation.

Main Methods:

• Literature survey and questionnaires were used to collate data on key parameters (time, temperature, pH, a_w) during meat ageing.
• Identified potential microbiological hazards including Shiga toxin-producing *Escherichia coli* (STEC), *Salmonella* spp., *Staphylococcus aureus*, *Listeria monocytogenes*, *Yersinia* spp., *Campylobacter* spp., and *Clostridium* spp.
• Modeled conditions for preventing mould growth and mycotoxin production using specific temperature, relative humidity (RH), and airflow parameters.

Main Results:

• Meat ageing can alter the load of microbiological hazards and spoilage bacteria compared to standard fresh meat.
• Defined and controlled ageing conditions can result in microbial loads equal to or lower than those in standard fresh meat preparation.
• Specific time and temperature conditions were identified to achieve similar or lower levels of *L. monocytogenes*, *Y. enterocolitica* (pork), and lactic acid bacteria (spoilage indicators).

Conclusions:

• Controlled meat ageing offers a viable method for managing microbiological hazards and spoilage bacteria.
• The study identified specific environmental parameters (temperature, RH, airflow) crucial for preventing microbial contamination and spoilage during ageing.
• Additional control measures can further enhance the microbial safety of dry-aged beef, ensuring safety equivalence to standard practices.