Question

when using frozen food items one should take out the required quantities;thawed food should never be refrozen

Answer 1

It's Safe to Refreeze Thawed FoodThawed food can be safely returned to your freezer provided it was thawed safely in the first place. The worst way to thaw frozen food is to let it sit out on your kitchen counter. Tina Hanes, a registered dietitian with the USDA's FSIS, told The New York Times:1"… [B]acteria like it warm, like we do, and multiply rapidly at room temperature. Thawing on the counter is not safe, period. You should never do that."In fact, it's said the greatest factor impacting whether your food is "safe" isn't whether it's been previously frozen but rather is related to how much time it spends in the temperature "danger zone" (between 40 to 120 degrees F).2In addition to thawing on the counter, thawing frozen meat, poultry, or seafood by running warm water over it is also risky from a food-safety standpoint. If you need to thaw meat or poultry quickly, it can be run with cold water over it, or submersed in cold water, changing the water every 30 minutes until it's thawed.3If you use this latter method for thawing, it should be cooked immediately – not refrozen or put back in the fridge. The USDA further advises:4"Once food is thawed in the refrigerator, it is safe to refreeze it without cooking, although there may be a loss of quality due to the moisture lost through thawing. After cooking raw foods which were previously frozen, it is safe to freeze the cooked foods.If previously cooked foods are thawed in the refrigerator, you may refreeze the unused portion. Freeze leftovers within 3 to 4 days. Do not refreeze any foods left outside the refrigerator longer than 2 hours; 1 hour in temperatures above 90 °F. 

If you purchase previously frozen meat, poultry or fish at a retail store, you can refreeze if it has been handled properly."