What's the Rule on Refreezing Food?
If I make a large amount of chicken stock and freeze it in portions, then defrost some and make a soup or stew, is it safe to refreeze the finished dish?
We have often heard people quote the Universal Food Law not to refreeze food that has been frozen and thawed. We are here to tell you that's wrong. Often the question of freezing has to do more with flavor and texture than safety but yours has to do with neither.
There is no blanket prohibition on refreezing food. There is, however a prohibition on thawing food, handling it badly, and then freezing it again.
One so-called Universal Food Law states that as long as a thawing frozen food still contains some ice crystals, you can safely refreeze it. From the point of view of safety, though, if you have a frozen food and thaw it completely in the refrigerator (therefore keeping it below 40°F (4°C) at all times), you can safely refreeze it. There are limits, of course. If the food was near it's "use-by date" when you first froze it, you cannot let it sit for days on end in the refrigerator before deciding to pop it in the freezer again. But if the food was fresh when frozen, kept at the safe temperature, and still is fresh, you can safely give it another round in the freezer.
If food defrosts in your freezer during a lengthy power outage, you need to verify that it stayed below 40°F before you let it refreeze when the power comes back on. We have dragged ourselves grumpily out of bed in the middle of the night when the power was restored to check on foods in the freezer. If you wait until morning when everything has frozen up again, you will have no way of knowing whether your foods went out of the safe-temperature range.
Now, freezing and thawing is not for sissy foods. The freezing process creates all sorts of crystals that stretch and tear fragile cell walls, redistributes juices, and creates other problems. Likewise thawing can cause a lot of moisture to seep out of those broken cell walls. So if you freeze and thaw, refreeze and thaw, you are going to notice a serious decrease in the quality of your food.
But on your question of thawing some stock to use in another dish yes, you absolutely can thaw a frozen food, cook it or cook with it, and then safely freeze the finished dish. This implies that all the ingredients are fresh, that you handle them properly, that you are clean and tidy, and that you do not let the foods linger in the zone between 40°F and 140°F (60°C) where bacteria multiply at exponential rates.
If you handle food properly, you can have a large stash of safe, flavorful frozen dishes and ingredients available for use when you want and need them.
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