Will Mussels Open When Frozen?

It is always best to enjoy your seafood as fresh as possible, but often it needs to be frozen for transport, to prevent waste, or to have fresh ingredients during the off-season. If you have decided to freeze some mussels, you may be worried that their shells will open during the process and whether they will still be safe to eat if they do.

Live mussels frozen in an airtight container may open their shells to breathe. The adductor muscle may also relax as the mussels die, causing them to open as theyre being frozen no matter what container is used. However, if you cook your mussels before freezing, they will all have open shells.

It is commonly known amongst seafood enthusiasts that you should never eat a fresh mussel with an open shell that won’t close. While this doesn’t always apply to frozen mussels, it is helpful to know why gaping shells are a potential problem and what the freezing process entails so that you can feel confident about your mussels before popping them into your next paella.

Do Mussels Open When Frozen?

Mussels have two hard shells that they keep closed around their soft bodies. Two adductor muscles keep the shell tightly shut most of the time. The shell opens up or gapes when these muscles go slack. The adductor muscles might stop holding the shell closed for two reasons.

What Causes Mussels To Open?

If a mussel is taken out of the water, it might settle its muscles and open up to breathe. If you encounter a fresh mussel with an open shell, give it a light tap or squeeze to see if the muscles will activate and close the shell. A mussel that closes its shell on its own is alive and just getting some fresh air.

The other reason a shell might be open is that the mussel has died. A dead mussel will not have functioning adductor muscles, so the shell won’t have anything keeping it closed anymore. If you encounter a mussel with a shell that doesn’t stay closed when squeezed, you should leave it and move on. 

Why Would Frozen Mussels Be Open?

If the mussel was alive when it was frozen, it might have opened its shell as it died. This doesn’t happen with every mussel, however, so it may be that only some are open while the others are closed. All cooked mussels have open shells, so if the mussels were cooked before they were frozen, then they will all be open. In both cases, the mussels are perfectly safe to consume.

How Do You Freeze Mussels?

Live mussels will die during the freezing process, so it is vital to be sure they are fit to eat before putting them in the freezer. You can also cook mussels before freezing, which is more likely to preserve the taste and texture. Before getting into the how-to’s for each method, and the effect it will have on their shells, you must first know how to select mussels that are good to eat.

How To Choose Fresh Mussels

Seafood is notorious for making people ill if it isn’t fresh enough or prepared incorrectly. Mussels, in particular, are prone to spoiling quickly, so you must know which are good to eat and which to discard before preparing and consuming them.

Here is a list of things to look for when purchasing your mussels fresh:

  • Mussels should smell fresh, like the ocean. If they have a fishy smell, they are most likely spoiled.
  • The shell of a live mussel should be wet, shiny, intact, and tightly closed. Mussels with broken shells or shells that don’t close when tapped or squeezed should not be consumed.
  • Fresh mussels should be sold in a mesh bag or a container with an open top so that they can breathe. If you see mussels being sold in a closed container, don’t buy them. These mussels will likely have suffocated and died by the time you get home.

How To Freeze Live Mussels

If you’ve purchased a bag of frozen, uncooked mussels, you must be confident your supplier would have kept the above points in mind before freezing. If you have bought or foraged fresh mussels and are sure that they are fit to eat, then you may decide that you want to freeze them yourself.

These are some steps that you can follow to freeze live mussels.

  1. First, clean your mussels by running them under cool water. Use this as a chance to check for any damaged or open shells.
  2. Debeard the mussels by pinching the beard with your forefinger and thumb and tugging firmly.
  3. Double-check that all the mussels are alive by gently squeezing any open ones. Remember, they should close and stay closed on their own if they are still living.
  4. Place the mussels in an airtight container to preserve freshness. Leave some space to allow for the expansion of the liquid.
  5. Put the container in the back of your freezer. The mussels will keep fresh for up to three months.

The mussel shells may open for two reasons. Firstly, the mussels die when frozen, so the adductor muscles will stop working. Secondly, they may open their shells to seek air. The mussels will still be good to eat once thawed.

How To Freeze Cooked Mussels

Not everyone thinks that freezing fresh mussels is the best option. Many seafood enthusiasts agree that cooking mussels before freezing them is safer and will also preserve the taste and texture of the meat.

Here are some basic steps to follow should you decide to pre-cook your mussels.

  1. Clean, debeard, and double-check your mussels as laid out in the first three steps above.
  2. Spread your mussels out evenly in a wide pot with a liquid of your choice. Some examples could be water or something more flavorful like broth or wine.
  3. Simmer or steam your mussels until they open. Check on them after three minutes and remove any that open up. Continue cooking until they are all open.
  4. Once removed from the pot, allow the mussels to cool to room temperature before placing them in an airtight container. Allow for some room for any expansion of liquids while freezing.
  5. Place the container in the back of your freezer and use it within three months.

As you may have guessed, a bag of frozen, pre-cooked mussels will all have open shells. The shells open up during cooking because the adductor mussels stop working as the mussel dies.

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There are two reasons why you might find some open shells in your container of raw, frozen mussels. The shell might have opened as the mussel tried to find more air to breathe, or the adductor muscle might have relaxed as the mussel died during freezing. Neither reason is anything to be concerned about, and you can still add them to your meal.

It’s better to cook mussels before freezing them. Cooking will preserve their taste and ensure all mussels are safe to eat. When mussels are finished cooking, their shells will open as the adductor muscle stops working. All pre-cooked frozen mussels will have open shells, so there is no reason to be concerned.