Thawing meat and fish

Why

Freezing does not kill bacteria, it only stops them multiplying, and as soon as the surface of meat or fish warms above fridge temperature they multiply again (Cooling and storing leftovers card). On the worktop the surface thaws and warms while the centre is still frozen, so the outer layer spends hours in the warm; that is why the US USDA and the UK FSA advise thawing in the fridge or, in a hurry, in the microwave just before cooking, and the USDA and FDA also allow a leak-proof bag in cold water. Campylobacter from raw poultry survive freezing and, according to the BfR, after thawing are found mainly in the thaw liquid, so meat is thawed in a bowl on the lowest shelf and the liquid is poured away (Raw poultry and cross-contamination card). Thaw vacuum-packed fish as the label says, usually taken out of the packaging: without air and above 3 °C, Clostridium botulinum type E, which forms a deadly toxin, can grow in it. A piece that is not thawed right to the centre cooks unevenly, so check the centre before cooking and confirm doneness with a thermometer (Internal temperature of meat card).

How to do it

• The fridge is safest: put the meat or fish covered in a bowl on the lowest shelf; a small pack takes about a day, a whole bird roughly a day for every 2 kg.
• Use thawed meat and fish as soon as possible: the FSA advises within 24 hours, the USDA within 1–2 days for minced meat, poultry and fish.
• In a hurry, submerge the meat in a leak-proof bag in cold water, change the water every 30 minutes, allow about 30 minutes per 500 g, then cook it straight away.
• Thaw in the microwave only what you will cook straight away: use the defrost setting, turn the meat and take it out while it is still icy but pliable.
• Do not thaw on the worktop, in warm water or near a radiator; pour away the thaw liquid, wash the bowl with detergent and your hands with soap.
• Thaw vacuum-packed fish as the label says, usually out of its packaging; shrimp and thin fillets can be cooked from frozen, just a little longer.

If it goes wrong

Meat or fish that thawed overnight on the worktop is better thrown away: the surface was warm for a long time and cooking does not destroy toxins some bacteria may have formed. The USDA allows raw meat thawed in the fridge to be refrozen, the UK FSA mentions only refreezing after cooking; cooking it first is the safer choice. Always cook meat thawed in water or the microwave before freezing. If the centre is still frozen, let it finish thawing in the fridge, or allow a longer cooking time and measure the core temperature.