Yes, discard them. They should have opened when cooked before freezing - if they had been live and edible.

This post was edited by olychick on Sat, Dec 29, 12 at 19:27

Hope I've caught you in time. It seems the mussel opening thing is a myth- Here is an article from a very respected Australian science lecturer:
Also, I would think a commercial producer would have fairly stringent checks on the safety of their product, or people who haven't heard about this "rule" would be going down like flies.
It's actually while they are alive that the opening/closing thing works- before cooking, when you rinse them in fresh water most will open their shells. If you tap on them they should close, if they are still alive. The ones that don't, you should toss, as they are the dead ones.

Here is a link that might be useful: Is mussel opening a reliable guide to edibility?

If they were fresh mussels I'd be concerned but frozen are dead...dead.dead so I would not expect them to open or close like fresh

The mussels were COOKED before freezing. If they didn't open when cooked and were frozen closed, I would discard. Of course they wouldn't open for the consumer after being cooked and frozen. One of my best friends owns a mussel farm here in the PNW. I know she will not eat/serve mussels that don't open when cooked.

For what it's worth..... when i buy mussels for two people - about 1.4kgs, I'll probably get 2 or 3 that won't open so I throw those away - not worth the risk.

I got very sick on mussels years ago and haven't been able to eat them since. Well, I tried once but couldn't palate them.

Opening/closing only applies to fresh mussels but one would think that since they were fresh when cooked, they would have opened. I'd toss any unopened ones.

Am I the only one who would change the menu if all I could buy were frozen pre-cooked mussels? Or do people use these as an ingredient a lot?

Here, I find frozen seafood more reassuring than fresh unless I knew someone had been to the coast (5 hours drive one way) that day or the day before.
At the Whole Foods, I think they probably have daily deliveries but everywhere else, no.

I live by the sea so eat fresh but if I lived a long way away, I'd choose frozen too.

If I were land locked and far from the ocean, frozen would be the only alternative, save for a loooong drive to get fresh. I'm sure price of fresh seafood is a consideration to. Luckily I can ride my bike to the harbor/beach and don't have to worry about it.
Yes, throw the unopened ones out. No need to take chances with bad mussels. NancyLouise

One of the reasons for fresh mussels is the copious delicious juice you get after cooking them.

dcarch

I was told by an employee at the local supermarket that local restaurants buy frozen mussels when they are a 2 for 1 deal. I asked the seafood lady if this was true, and she said it was. They microwave them and serve to paying customers as fresh. And here we are, at the beach! That is absolutely stupid!

If you read the article that Colleen posted you'll understand why some don't open with cooking. The problem for the diners is having to prise them open. I woldn't bother serving closed ones for that reason.

The joy of cooking them fresh is that you know that each one that you've cooked was closed and alive when it went into the pot. So you don't have to worry about the safety of a closed one. I might be more concerned about a product that I hadn't cooked myself.

i just want to know how they close them back up after they cook them the 1st time

because once you cook them they are open and dead how do they close them back up

I would imagine "they" don't "close them back up", the mussels in question didn't open in the first place. As has been pointed out, not all mussels which are OK to eat open up on cooking.

Yes, you can cook them and close them.

First you make sure they are all alive, then you put them all in a Foodsaver bag, add a little liquid and vacuum seal.

Then you cook them in the bag. They will be all cooked but they will not be open.

dcarch

I really appreciate this discussion. My picky 8 YO asked for mussels for dinner...whoa where did that come from...and I know nothing about cooking them. I bought them "live" huh? The seafood clerk gave me a quick tutorial.

The only mussels I've ever had was years ago in Brugge as it's a favorite Belgian dish.

thanks i work in a restaurant in central pa we get them pre cooked because it is so hard to get fresh mussels here and yes they are closed after being cooked