How to defrost fish safely (and preserve its texture)

Fish is a delicate food. Once it comes out of the freezer, it should never spend too long in what’s called the danger zone, between 40°F and 140°F (4°C to 60°C). That’s the temperature range where bacteria multiply the fastest.

If thawing isn’t done properly, you can end up with:

• rapid bacterial growth,
• a mushy or unpleasant texture,
• fish that tastes bland or waterlogged.

The safest thawing methods are also the ones that give you the best results in the kitchen - both for flavor and for food safety.

If you're ahead of the game, this is definitely the method to choose. It's gentle, safe and respects the flesh of the fish.

Simply remove the fish from the freezer and place in the fridge, ideally the evening before. Thawing takes place gradually, at a constant temperature, which limits thermal shock.

If the fish is vacuum-packed, it is advisable to slightly pierce or remove the packaging before chilling. The aim is to introduce oxygen, to avoid the development of toxins in an anaerobic environment.

Place the fish on a plate or tray, wrap lightly and place in the coldest part of the fridge, often at the bottom. Depending on thickness, allow between 8 and 12 hours.

Once thawed, blot carefully with kitchen paper before cooking.

Thawed fish should never be refrozen. So it's important to think carefully about how much to take out of the freezer.

Forgot to take the fish out in advance? No need to panic. There's a quick and safe method, as long as you follow it carefully.

The fish must be placed in an airtight plastic bag. It must never be in direct contact with water, otherwise it will become soft and bland.

Then place the bag in a bowl or tub filled with cold water, or under a gentle stream of cold water. Even cold water transmits temperature better than air, which speeds up defrosting.

Depending on the thickness of the fillets, this usually takes between 20 and 60 minutes.

To check, press gently on the fish: it should be supple, but still quite cold. Once defrosted, remove immediately from the bag, pat dry and cook immediately.

Microwaves can help out, but should be used as a last resort. Its main drawback is that it heats unevenly: some parts of the fish may start to cook while others remain frozen.

If you really have no choice, use only the "defrost" function and remove the fish when it is still cold to the touch. Above all, it should be cooked immediately afterwards, without waiting.

Certain practices should be avoided at all costs, even if they seem quicker or more convenient.

Thawing fish at room temperature on the work surface is a common mistake. So is plunging it into hot water. These methods expose the fish to a rapid rise in temperature, ideal for bacteria, and are highly detrimental to texture.

Fish thawed too quickly often becomes soft and unpalatable.

Occasionally, a fish may be soft despite having been properly defrosted. In this case, the problem doesn't necessarily lie with you.

During freezing, the water in the fish's cells freezes. If the fish has not been frozen quickly enough, large ice crystals can form and damage the cells. When thawed, the water escapes, leaving softer flesh.

Thick fillets and steaks are more susceptible to this phenomenon. In this particular case, the cause is often linked to the freezing process itself, and not to the thawing method used at home.

As with all raw foods, it is essential to wash hands before and after handling fish. Surfaces, knives and boards should be thoroughly cleaned, and packaging discarded immediately.

Once defrosted, fish should not be left at room temperature for more than two hours, and certainly not in very hot weather.

But this requires a little forethought and method. By thawing in the fridge or, in an emergency, in cold water, you preserve both the quality of the fish and your peace of mind.