Why can’t food be refrozen once it has been unfrozen?
In: Chemistry
It can, but there are two reasons not to.
First is contamination. Freezing slows the growth of bacteria and mold. When you unfreeze, that growth starts again. When you then freeze it again, all that contamination is still there.
Second is by freezing and unfreezing and freezing again, you are destroying the cells of the food, and dehydrating it, so it will taste worse and worse the more times you do it.
I’m going to add a bit to previous explanations. So when food is frozen slowly ice forms in larger crystals, which break the cell and other structures in the food. This makes more easily digestible by bacteria and more chemically active in general which accelerates the spoiling process of the food.
When you freeze food, bacteria and spores are typically not killed, but stopped from reproducing. whe you defrost food, those bacteria are allowed to reproduce again, and will continue to do so whilst it is refreezing, leading to them being at harmfull levels the second time you defrost.
You can refreeze things. I think this idea is spread because of food safety. When thawing and freezing, you often leave for exposed, refreeze bacteria and lose track of the actual safe expiration time.
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