United States
Hong KongThe four approved ways to thaw food
Four methods: under refrigeration at 5°C (41°F) or below, submerged under running water at 21°C (70°F) or below, in a microwave followed immediately by cooking, or as part of the cooking process itself. Room temperature is not one of them.
Four methods, and a fifth that every kitchen uses and no exam accepts.
Refrigeration
At 5°C (41°F) or below. Slowest, safest, and the one the Code prefers, because the food never leaves temperature control at any point.
It needs planning: a large turkey takes days rather than hours. Thaw on the bottom shelf so drip cannot reach anything below it, which is the storage-order rule doing its job again.
Running water
Submerged, under running potable water at 21°C (70°F) or below, with enough flow to carry loose particles away.
Every word there is examinable. Submerged, not under a trickle. Running, not standing in a sink of water. And 70°F or below rather than warm, because warm water thaws the surface into the danger zone while the center is still frozen.
Chicken sitting in a filled sink is the wrong answer even though the water is cold, because still water warms up and nothing carries the surface bacteria away. The word running is the whole rule.
Microwave
Permitted only when the food goes straight into cooking. A microwave thaws unevenly and leaves warm patches, so the food is already partly in the danger zone when it comes out.
Thawing in a microwave and putting it back in the cooler is a violation. That is the version the exam asks.
As part of cooking
Frozen straight into the oven, fryer or pot, provided it reaches its required internal temperature. Frozen chips into a fryer, a frozen burger onto a grill.
The catch is thickness. A frozen roast cooked from solid may hit temperature on the outside long before the center catches up, which is a cooking failure rather than a thawing one.
Why not the counter
Because thawing is not uniform. The outside reaches room temperature and stays there for hours while the middle is still frozen, so the surface - where the bacteria are - spends the whole time in the growth range.
That is also the reason time is not an accepted control here. There is no counter method with a safe number of hours attached.
The ROP exception worth knowing
Fish packaged in a reduced-oxygen environment carries a label saying to remove it from the packaging before or immediately after thawing. Clostridium botulinum grows without oxygen, and a vacuum bag thawing slowly is the condition it wants.
It is a small provision that appears more often than its size suggests, because it links thawing to reduced-oxygen packaging and lets one question test two areas.
Common questions
What are the four approved thawing methods?
Under refrigeration at 5°C (41°F) or below, submerged under running water at 21°C (70°F) or below, in a microwave followed immediately by cooking, or as part of the cooking process.
Can you thaw food on the counter?
No. Thawing is uneven, so the surface reaches room temperature and stays there for hours while the center is still frozen. There is no accepted number of hours for counter thawing.
What temperature should thawing water be?
21°C (70°F) or below, and running rather than standing. Warm water thaws the surface into the danger zone while the center is still frozen, and still water does not carry loose particles away.
Can you refreeze food thawed in a microwave?
No. Microwave thawing is only permitted when the food goes straight into cooking, because it leaves warm patches that are already in the danger zone.
Why must vacuum-packed fish be removed from packaging before thawing?
Clostridium botulinum grows in the absence of oxygen, and a sealed bag thawing slowly creates exactly those conditions. The label on reduced-oxygen packaged fish says to remove it before or immediately after thawing.