Frozen mussels, help!
September 20, 2008 8:41 PM   Subscribe

How to use frozen whole-shell NZ greenshell mussels?

Needed some mussels for a broth the other day, but couldn't get my hands on any fresh, so I ended up with a package of frozen whole-shell New Zealand greenshells. I've never worked with anything but fresh mussels, and realized I had no clue what was going on.
  1. Are they already pre-cooked? Most info I found about greenshells talks about a) fresh b) cooked & frozen on the half-shell or c) shucked, cooked & frozen. There's a conspicuous lack of information on the whole-shell frozen kind.
  2. What are some adjustments to think about when using them in recipes as a replacement for fresh mussels? In particular, when steaming them, how do you know when they're done, how do you know if any are bad, and should they be de-frosted prior to use?
My experience: I just tossed them in the broth to steam, but they never popped open the way good fresh ones do (photo). That freaked me out: were they all bad? I left them in far longer than I normally would have, but they still didn't open, yet when I forcibly opened them by hand, they didn't look bad (photo).

I ended up not eating them, but used the broth. Yummy, no side effects. I'm guessing they were at least blanched prior to freezing, with bad ones tossed at that point, but could use some reassurance.
posted by kanuck to Food & Drink (6 answers total) 2 users marked this as a favorite
I would not use frozen ones. I'm not an expert, but if they didn't pop open after you steamed then, then they're no good.

Fresh ones pop open because they're alive and react to the steam. Frozen ones are quite dead before steaming.

You just don't know what you're getting if you don't buy them fresh... although the 'Omnivore's Dilemma' reader in me says that it's not worth buying mussels from New Zealand - even if they were string-farm raised - because they were flown to you on a jet that totally taxed the environment to get them to your table. LOL.

Buy fresh, buy as local as you can!
posted by matty at 9:47 PM on September 20, 2008

From the website you linked to in your question:

Storing and Cooking

Fresh-frozen New Zealand Greenshell™ Mussels
New Zealand Greenshell™ Mussels are snap frozen to lock in their quality. Fresh-frozen New Zealand Greenshell™ Mussels will retain their just harvested flavor and quality for up to twelve months when stored at -18°C or O°F or colder. Cooking from frozen at high heat for a short time produces the best results. If the mussels are not going to be heated, minimum thawing at room (ambient) temperature produces a tender succulent product. They must not be over thawed, refrozen or left sitting in their own juices or water.

Hope that helps.
posted by longsleeves at 10:51 PM on September 20, 2008

Best answer: Frozen mussels have actually been pre-cooked extremely quickly. The method used (very quick steam cooking under pressure) keeps the mussels closed. Because live mussels open when cooked, you can tell which to throw away (the ones that were already dead and thus more likely to be dangerous).

You cannot tell this when buying frozen mussels. On the other hand, you can't tell which shellfish were not cooked from live specimens when you buy canned clams, smoked oysters, or frozen mussels without the shell.

I have no problem with buying canned clam meat and so would suggest that I don't think you need to worry about buying frozen mussels. That said, fresh is usually cheaper and the quality higher.
posted by ten pounds of inedita at 1:00 AM on September 21, 2008

I would stick them into a paella towards the end of the cooking time. As they are precooked then frozen they only need about 5 mins.
posted by jan murray at 2:57 AM on September 21, 2008

Response by poster: Thanks everyone, consensus seems to be they are pre-cooked.

matty, I definitely prefer fresh and local whenever possible, sadly that's not always possible.. this is my first experience with the frozen kind.

longsleeves, I did read that site I linked to, notice that the content you quote never actually says that fresh-frozen mussels are cooked prior to freezing (in fact, it says "cooking from frozen.. produces the best results", which implies to me they hadn't already been cooked). While I've not heard of mussels being eaten raw, other bivalves certainly are, so even the "if mussels are not going to be heated.." part wasn't conclusive to me.

ten pounds, would you happen to have a reference to the method of pre-cooking that you describe? I'm curious how the mechanism keeps the shell closed -- my understanding is that cooking breaks down the adductor muscle(s) holding the shells closed, yet I need quite a bit of force to get these frozen ones open, even after extensive cooking.
posted by kanuck at 3:30 AM on September 21, 2008

A Google search for ("frozen mussels" + autoclave) or ("frozen mussels" plus "pressure cooker") doesn't come up with much detail other than to show that it's done.

I got my info from watching it done on a cooking show. Might have been Good Eats, might have been Chef at Home, Chef at Large or The Inn Chef (Michael Smith is a PEI-based chef). Actually, it probably was one of the latter.
posted by ten pounds of inedita at 3:22 PM on September 21, 2008

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