Meat intended for freezing: EFSA assesses bacterial growth in meat before it reaches consumers

The way meat is stored by food business operators before it reaches consumers can affect how bacteria grow. This applies both to harmful bacteria such as Salmonella and Listeria, and to bacteria that spoil meat’s smell and appearance.

EFSA’s experts looked at how storage conditions – such as temperature, vacuum-packaging and time – affect microbial growth between slaughter and freezing as well as during subsequent defrosting and storage.

Methodology

To carry out the assessment, experts compared various meat storage and defrosting scenarios with a reference scenario (meat stored without vacuum packaging at 7°C for 15 days), observing differences in microbial growth. Experts applied the concept of equivalence time, using mathematical models to predict the amount of time meat can be stored before freezing under different conditions until it reaches the same microbial levels as in the reference scenario.

Key findings

• When storing meat at 7°C that was vacuum-packed immediately after stabilisation The time after slaughter needed for carcasses or meat cuts to reach a core temperature of 7 °C and for the meat’s pH to becomes stable. This process is done through chilling and normally takes a few days, equivalence time before freezing was determined by Salmonella and was reached in 5-6 days of post-slaughter storage.
• When storing meat at 3°C, equivalence time before freezing was determined by spoilage lactic acid bacteria and was reached in 29-30 days post-slaughter. In certain situations, when initial bacterial contamination of meat is high, spoilage may happen before reaching these predicted equivalence times.
• When defrosting meat at 4°C or 7°C under the conditions assessed, bacterial growth was absent or limited.  
• Further storage of meat at 4°C for 7 days after defrosting may lead to additional bacterial growth depending on the storage conditions, suggesting that pre-freezing times in some of the scenarios should be shortened to reach equivalence with the reference scenario.  

Background and next steps

The European Commission asked EFSA to carry out this risk assessment A specialised field of applied science that involves reviewing scientific data and studies in order to evaluate risks associated with certain hazards. It involves four steps: hazard identification, hazard characterisation, exposure assessment and risk characterisation to address gaps and inconsistencies in some of the EU rules on the microbiological safety of meat intended to be frozen. Based on these findings, the European Commission may propose changes to EU legislation.