I love everything from the sea, but am a little squeamish when it comes to cooking shellfish etc. myself

I have a large bag of Frozen, shell-on Black Tiger prawns, as well as two trays of 'Jumbo' Black Tiger prawns in my freezer (these are enormous, almost Lobster-like, three per pack).

My particular issue with these is that while they are well in-date, we have had two x 6 to 8 hour planned power-outages over the time I've had them in the freezer. I followed the usual guideline, as in keep the freezer closed during the outage.

Should I be concerned, or just cook up these (still beautiful looking) Crustaceans?


(My first post here, so please forgive any errors.)

  • 7
    A common Internet tip for assuring your freezer didn't experience a power outage that could affect the frozen foods within is to place a plastic cup of water in there, wait until it freezes completely, then placing a small coin on top. Keep this upright in the freezer as an indicator. If a power outage occurs and lasts long enough for the water to unfreeze, the coin will be at the bottom of the cup, and foods might be unsafe due to thawing completely and then re-freezing again.
    – John Doe
    Jul 15, 2019 at 10:58

3 Answers 3


Without knowing the internal temperature of your freezer for the duration of the power outages this is impossible to answer. Since these are planned outages, I assume you have experienced them before. Do items in your freezer remain frozen? At the very least, they will have experienced some freeze/thaw cycling, which would likely impact the texture of the prawns. It is obviously not ideal. So, yes, I would be concerned. How concerned is impossible to judge with the information provided.

  • Also knowing the size of the freezer would help determine the likelihood of these items be safe or not.
    – J Crosby
    Jul 15, 2019 at 14:48

If you haven't prepared ahead and done the coin-on-ice trick that John W. mentioned in his comment, I would suggest that you look for something in your freezer that's 'IQF' (individually quick frozen).

In this case, it might be the shrimp / prawns. It might be a bag of frozen peas or corn. Basically, something that when you bought it was a whole lot of little frozen bits, rather than a solid block of frozen something.

If you have an automatic ice maker, you can also use that an indicator -- they'll all be stuck together if there was thawing.

If it's now a solid block, then your frozen items thawed and re-froze. Now, they might still be okay ... your periods were short enough that you can probably just treat them as if they were in the fridge for that time, and cook them right away ... just don't assume they're fine being left in the freezer for longer.


We experience power outages with every hurricane, so, frequently. The general rule of thumb is that frozen food will remain good for 3 days as long as you don't open the freezer door. The US FDA webpage on Food and Water Safety During Power Outages and Floods indicates 2 days,

Keep the refrigerator and freezer doors closed as much as possible to maintain the cold temperature.

  • The refrigerator will keep food cold for about 4 hours if it is unopened.
  • A full freezer will keep the temperature for approximately 48 hours (24 hours if it is half full) if the door remains closed.

which would indicate that your shellfish should be fine.

Really glad you asked as I've been using outdated information.
Enjoy your Prawns!

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