Defrosting done right - what you need to know

By PHT South Africa on 25 September 2019

Whether you prepare food for your family or run a food service, defrosting meat the right way is critical. Deléne Boshoff of PHT South Africa explains why and shares advice for doing defrosting right.

Risk and regulation

The short answer to why you need to defrost meat properly is that it reduces the risk of food poisoning. Food poisoning develops when you eat food that contains harmful bacteria. Meat that is not defrosted correctly can quickly become a breeding ground for such bacteria. ‘If you defrost in a way that increases the chance of contamination, you increase the risk of unsafe food,’ says Deléne.


If the risk of food poisoning does not scare you, food hygiene regulations might. Regulation 638, which stipulates hygiene requirements for food premises and transport of food, lists specific requirements for defrosting frozen food, including meat. The regulation is law and non-compliance may result in fines or shutdown of your food service, which could have serious financial implications.




The meat of the matter

Defrosting meat properly means defrosting it evenly and to a temperature where bacteria cannot grow easily. The best way to do this is in the fridge. There are two factors at play: thermal equilibrium and bacterial growth.


Simply put, thermal equilibrium means that two objects of different temperatures will warm or cool until their temperatures are the same. The temperature inside a freezer is typically between –18 °C and –24 °C. So, when frozen meat is taken out of the freezer, it starts to warm because the surrounding air is warmer that it was in the freezer. Frozen meat starts to return to its original raw state above 0 °C. 


Bacteria generally do not multiply at temperatures below 5 °C. The temperature inside a fridge is typically about 4 °C, which means that bacteria that may have been present in the meat before freezing will not grow while defrosting in a fridge. This lowers the risk of food poisoning.


Why you should never defrost meat
on the counter top

Understanding the principles behind safe defrosting, you can now appreciate what happens when meat is defrosted at room temperature. To start with, room temperature is in the so-called temperature danger zone where bacteria multiply easily – between 5 °C and 60 °C. If meat is left out on a counter top, the outside will defrost fairly quickly, but the inside will still be frozen. If left to defrost all the way through, the surface will continue to warm, moving into the danger zone and allowing bacteria to multiply rapidly.


Doing it right

‘You can have all the systems and compliance documents in place, but if you don’t do the right things, food hygiene fails,’ says Deléne. So, make sure you do the following to defrost meat safely:

  • Wash your hands thoroughly before taking meat out of the freezer. This limits the risk of cross-contamination.
  • Use a drip tray so that the juice drips away from the meat and collects in a dish below.
  • Place the drip tray on the bottom shelf of the fridge so that if any juice does spill, it won’t drip onto other foods.
  • Plan your time. Mince, stewing meat, steaks, chops or chicken pieces should defrost over a period of about 24 hours. For roasts or large on-the-bone cuts, allow 24 hours of defrost time for every 2.5 kg.
  • Cook the meat soon after it has defrosted. Defrosted red meat cuts such as steaks, chops and roasts will generally keep for another 3 days in the fridge. Mince, stewing meat or chicken pieces should be cooked within a day of fridge defrosting.
  • Be careful with refreezing. Partially defrosted meat can be refrozen, but only if the surface temperature is still below 5 ° If the meat’s surface is still covered with ice crystals, refreezing is usually possible, but use a thermometer to check. Note, however, that refreezing may affect the quality and taste of the meat, so try to avoid it if possible.


A word of warning

Defrosting meat in a water bath is possible, but not recommended. Plastic wrapping is seldom water-tight, which means there is a high risk of cross-contamination. The water also has to be replaced every 30 minutes to prevent it from warming to an unsafe temperature. This makes the technique impractical, wasteful and risky.

Contact PHT South Africa  for information on climate-controlled systems for large-scale meat defrosting.


Read more

  1. United States Department of Agriculture. The big thaw – safe defrosting methods.
  2. American Meat Science Organization. Methods for defrosting frozen meat and poultry.
  3. Australian Institute for Food Safety. 4 methods for defrosting food safely.
  4. Food Safety Information Council. Temperature danger zone.
  5. South Africa Department of Health. Foodstuffs, Cosmetics and Disinfectants Act, 1972 (Act no. 54 of 1972). Regulations governing general hygiene requirements for food premises, the transport of food and related matters. Government Gazette. 22 June 2018.