I am steaming clams today and I recall my friend warning me under no circumstances should I eat any of clams that remain unopened after steaming. He told me to throw those stubborn clams out, but I wonder why. Is there a problem with opening and eating the last holdout closed clams after all of them are steamed?


2 Answers 2


Before steaming the clams, they should all be closed. If any of your clams are open, give them a tap and if they stay open, then it is bad and you should take it out of your batch to prevent it from ruining the other clams.

After you have steamed the clams, most of them should be open. The few clams that stay closed doesn't necessarily mean they are bad. Take a thin knife and pry it apart. It's very easy to tell if the clam is bad just by smell.

Edit: After being called out on my fallacy to believe certain kitchen myths without further research, I learned that indeed it is a myth that clam/mussel that refuse to open after being cooked is unsafe to eat.

A clam/mussel has a shell with two halves. These shells have elastic ligaments that naturally want to be open. To keep the shells closed, they have adductor muscles to hold the shells together. Most of the time the heat will denature the proteins in the adductor muscles causing it to release the shells. But sometimes it can cause the muscle to "seize" and hold firm.

This article gives a background of how this kitchen myth started: Mussel Myth

Clam or Mussels that refuse to open after they have been cooked IS NOT an indicator that they are bad. Pry them open and it can easily be determined whether they are bad by the smell.

  • 2
    There are some very good chefs that say closed mussels are safe too.
    – GdD
    Aug 8, 2015 at 19:16
  • @GdD I think its more about statistics. Generally mussels will have a much higher chance of being bad if its closed compared to clams. So as a catchall "safe" answer, mussels are considered bad if its shell is closed after steaming.
    – Jay
    Aug 8, 2015 at 19:20
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    @jay do you have a source for your assertions re. mussels being more likely to be unsafe if they're closed after cooking? I seem to recall it being a baseless myth that cropped up in a cookbook and was repeated enough that it became common 'knowledge'. Aug 8, 2015 at 19:30
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    Say I pry it open, Since I can't go by looks (all clams are ugly to me!) will it be obvious by the smell that it is no good? I ask because I am cooking these in garlic, and that is pretty strong. Will it be obvious? Sorry that I don't know enough about these.
    – ychirea1
    Aug 8, 2015 at 20:04
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    @ychirea1 the smell of seafood that have gone bad can definitely be smelled over garlic.
    – Jay
    Aug 9, 2015 at 2:20

At least in the UK bivalves are treated with uv light which takes care of nasty hepatitis a etc.

Logically a bivalve has to contract it's muscle to close therefore an open one before cooking is dead but not necessarily bad - we serve most other meats dead. I had a batch once where half were open on arrival and they tasted just fine ...I couldn't bear throwing them away. (But you might not be that brave)

When Cooked the muscle stops contracting, denatures and often looses its insertion therefore she'll naturally pries open due to the structure/ligaments. But I'm not sure why some shells don't open - a barnacle on the hindge?

  • There's nothing wrong with them being open on arrival if they close when you tap on them.
    – Catija
    Aug 13, 2015 at 15:38
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    i meant to add that they didn't close on tapping. The flesh looked fresh and cooked up fine. My point is that if it otherwise looks fresh then it may be ok but I can't advise anyone else to eat them where as I was prepared to. We eat plenty of other meat that's not still alive.
    – worthwords
    Nov 28, 2015 at 3:17

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