Hello again, Graham and welcome back to Just Answer.
My name is XXXXX XXXXX it will be my pleasure to help with your question today.
My apologies that you did not receive an earlier answer; however, different experts are online at varying times and I recently logged in and read your question.
It depends on the company that sells the shrimp. Some are processed and deveined before they are frozen and sold. If your package says 'deveined shrimp', this has already been done, so, easier for you.
Also, look at instructions on the package, for preparation. For example, if it says defrost for a certain number of hours in the fridge or outside the freezer, or run under cold water to defrost, it should also include the information on how to devein, or at least say, 'devein before cooking'; if it does not say that, I would presume they are already deveined and you don't have to worry.
If you see no dark vein (intestinal tract), running through the shrimp, then I would assume they have already been deveined as part of the processing before freezing. Look for a customer service or company phone number on the package that you can call with questions about the product, so you can ask them if they have been deveined before being packaged.
I hope this helped!
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