Prawns taste like bleach

[Mrsworriedmum]

I’ve just eaten my dinner (prawn stir fry) using finest raw king prawns from Tesco. I ate most of them fine, but the last few had a real bleach taste. I didn’t think much of it, but then I googled it and with results suggesting they may have been bad. They are over a week within date, delivered today. Some things say that’s just a taste sometimes from how they’ve been stored….any experience?

Have you still got the packaging? Some seafood gets treated with STPP (sodium tripolyphosphate) which can give a bleachy taste on/after cooking. It's not necessarily an indication that they were off (but they also weren't necessarily naturally as fresh, plump and luscious as they looked after treatment!).

They are washed in chlorinated water then packed and gassed - to preserve them

If using fresh ( and seriously its easier to by frozen, less chemicals used in the preserving ) then take them out of the packet a couple of hours before use and leaving to drain in a sieve or colander and then dry with kitchen towel

Over a week, for fresh prawns?

That seems highly unlikely.