Is defrosting and re-freezing meat and fish dangerous?!
Answers:
Every time you defrost and then refreeze the product, you are damaging the texture. Not a good thing to do. Why not cut the product into pieces before freezing the first time, and use as needed.
It depends on how you are defrosting it. The danger zone is above 40F and below 165F. Above 40F, the bacteria in the meat (I'll use the term for both meat and fish) grows rapidly. Above 165F, the bacteria are killed by the heat. If you are above 40F but below 165F, the bacteria will grow. Many bacteria (including Clostridium botulinum) create a toxin as they grow, and while temperatures above 165F will kill the bacteria, it will not get rid of the toxins already generated. So, if you keep something at a temperature above 40F but below 165F for too long, the toxin can accumulate, and even if you cook the meat above 165F the toxin will still be there. (Clostridium botulinum causes botulism.)
If you defrost the meat in the fridge (which should be set for 40F), then it won't get warm enough for the bacteria to flourish. If you freeze it again, all is well.
If you defrost the meat by warming it up but you don't cook it, then you've just given the bacteria a good chance to grow, and if you freeze it, the bacteria are still there.
Multiple freezing and thawing cycles, even if done in the fridge to control bacterial growth, will still damage the cells in the meat, making the meat not very tasty. But not dangerous.
It isn't about killing the vitamins and minerals, it is compromising the quality and safety of the meat
You should never thaw and re-freeze raw meat
You can thaw, cook, and freeze meat, that's not a problem
In your scenario you would want to thaw it completely, cook it all, then freeze any leftovers you wouldn't/couldn't consumer within 5 or 6 days.
dont know about the vitamins but you NEVER refreeze meat
Refrigerating food will not stop bacterial growth: just slow it. So do not refreeze food that has be defrosted for some time even if it has been refrigerated the whole time.