Why does mince go off?
To defrost meat safely it’s important to understand the basic scientific principles behind it. Meat has bacterial microorganisms which naturally occur across its surface. Unlike other cuts, minced meat has a larger surface area which allows bacteria to more easily spread.
Bacteria doubles every 30 minutes or so causing the mince to spoil faster than a larger solid piece of meat (like a steak). So, its shelf life is shorter to reflect this.
Refrigerating mince slows down the process and freezing stops it in its tracks. That is why meat will spoil in the fridge if not consumed by its use by date, whilst frozen meat will remain as fresh as the day it was frozen - until it is defrosted.
Defrosting frozen mince safely
All varieties of mince meat must be defrosted fully before cooking. Safe defrosting methods respect the microorganisms that naturally occur in meat and focus on maintaining conditions which prevent the bacteria from growing. Below we review the different ways you can defrost mince and highlight any safety issues:
Defrosting mince in the fridge
The fridge is the safest, slowest, most controlled way to defrost frozen mince. The average freezer temperature is -18℃ whereas the average fridge temperature is warmer at 2-4℃. This temperature difference is enough to begin to slowly thaw the mince but keep it below 5 ℃ when it begins to spoil.
Method: Place the sealed frozen meat pack onto a tray and place it on the bottom shelf of the fridge. A 500g block of frozen minced beef will take approximately 24 hours to defrost fully. Mince defrosted using this method should be cooked immediately or within the next 24 hours.
Defrosting mince at room temperature
Defrosting mince at room temperature is not safe and is not recommended. Any temperature above 4℃ (the temperature of your fridge) promotes bacterial growth. The temperature of your kitchen is likely to fall between 8-30℃ dependent on the time of the year. This will defrost the outside layer of meat quickly and promote bacterial growth, whilst the interior is still frozen. Meat that isn’t fully defrosted shouldn’t be cooked. Mince that has been defrosted in this way should never be refrigerated or frozen afterwards.
Defrosting mince in water
Frozen mince can be defrosted safely in cold water only. The principle behind this is to gradually raise the temperature of the frozen meat to the same temperature as the cold water, keeping it within safe temperature limits.
Method: Place the frozen mince in a watertight bag. Fill a large bowl with tap cold water then submerge the bag of mince under the water's surface. Change the water every 30 minutes to maintain a safe temperature. Thawing time will vary from 2-4 hours based on the weight of mince, size of the bowl and the room temperature but it is much quicker than the fridge method. Mince defrosted this way can be cooked immediately or refrigerated for up to 24 hours.
Warm water and hot water: Warm and hot water are not recommended for defrosting mince as it can result in uneven thawing and may accelerate bacterial growth making it unsafe to eat.
Defrosting mince in the microwave
The fastest way to defrost mince is in the microwave which takes just 5-10 minutes. Method: Remove all packaging and spread the mince onto a microwavable dish. Use the defrost setting and refer to the manufacturer's recommended time for defrosting mince. The microwave will alternate between defrosting and pausing and it’s a good idea to pause the defrosting regularly to break the mince up.
Microwaves use heat and the meat will begin to partially cook. It is for this reason that microwave defrosted mince must be cooked immediately (by your chosen method) and not returned to the refrigerator or freezer.
Defrosting mince in a frying pan
If you plan to cook the mince immediately, it can be defrosted safely in a frying pan.
Method: Add cooking oil to the pan and start heating the mince on a low temperature, breaking the mince apart as it thaws. Once fully thawed, turn the heat up and continue cooking. This will add approximately 10 minutes to the normal cooking time.
Is it better to cook mince frozen or thawed?
- Both methods are safe as long as the frozen mince reaches an internal temperature of 75℃ to eliminate bacteria.
- Thawing mince before cooking is likely to create more even cooking results.
- Cooking mince that is thawed is quicker than cooking frozen mince.
- Cooking frozen mince offers greater convenience.
- There is little difference between food quality and taste.