Why is re-freezing verboten?
Why is it that you should never refreeze foods that were previously frozen?
I've always assumed it had to do with trying to minimize the risk of contracting food poisoning. Is this the case? Or does it have to do with effects of freezing on food textures?
Like many people, I routinely freeze prepared dishes, such as stews and soups, that were cooked using meat that had been frozen. So the no-refreezing rule is not absolute, at least in this respect.
Does the rule only apply to raw food?
There's freezing and then there's freezing. A residential freezer rarely reaches zero degrees F, instead hovers in the 20-someodd degree range. IQF, commercial "Individually Quick Frozen" items are flash frozen rapidly. The difference in these two procedures is evident in the cellular structure of the foods,. Slow-frozen raw food tends to have more cell wall breakage which results in leakage. The faster the food freezes - and the colder it stays - the better the final product.
After the food is frozen, there is still some cell activity. The colder the freezer, the slower the activity. This is one reason it is possible to keep food in a commercial freezer for longer periods of time VS a residential refrigerator-freezer.
The main problem with thawing, re-freezing and re-thawing food is the loss of liquid due to the afore-mentioned cell damage in raw product. It is a quality issue rather than a health issue if the thawed food remains cold, below 40 degrees. However, if a chicken is thawed in the kitchen sink, reaches room temperature and is re-frozen there could be a health issue as well as loss of quality. It depends on how the thawing and re-freezing process takes place. The thawed food temperature is key.
I never hesitate to re-freeze food when plans change if the food has remained cold. If the raw food temperature reaches the 50 degree+ mark, I'll refrigerate it (beef or lamb) or cook it.
Edit: a CH poster contacted me to gently remind me that some residential freezers are indeed capable of keeping food at or below zero degrees F. I know since I own one of those and keep it at minus 5 degrees but I should have been more clear about *most* residential freezers. I am speaking of the single unit regrigerator-freezer units common in most kitchens, NOT free standing freezer units with their own compressor, etc. A "refrigerator-freezer" appliance is rarely capable of maintaining zero degrees in the freezer without freezing the lettuce in the fridge compartment. Sorry for the confusion.
It applies to raw food. As long as the defrosted raw food has been kept in the refrigerator and is not spoiled, it can be refrozen, but the texture and flavor usually suffer, I did it once with ground beef, later redefrosted and used in meatballs, with no damage. I've occasionally forgotten to return a partially-used bag of frozen raw fruit or vegetables to the freezer, and refroze the thawed bag. It ends up mushier, but usable.