Eating day old mussels ok?
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If they were refrigerated, it's fine.
Chris is a trusted source on General Cooking
I often make more mussels than I know we'll eat just so I can have leftovers in another dish. If you refrigerated your dish, you'll be fine.
pierino is a trusted source on General Cooking and Tough Love.
...and, chilled cook mussels taste really good too.