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Re-Freezing - Why Not?

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cracker222 | 21:17 Sun 24th Apr 2016 | Food & Drink
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I froze some leftover ham and some ham stock. Recently I made pea soup and added the ham (thawed and chopped) and the stock. Heated it all up. Lovely. I had too much so have frozen the remainder of the soup (including the ham and stock). Is it OK to re-freeze after the thawed item has been thawed and re-cooked? If not, why not? What is the science behind the adage that food should not be re-frozen?

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To my knowledge, anything that has just been cooked and cooled down is essentially sterile. Freezing it therefore poses no danger and on defrosting and prompt re-heating for immediate consumption it will be entirely safe. On the contrary, something raw that is defrosted and left thawed for some time will be subject to the risk of microbes already present...
21:50 Sun 24th Apr 2016
Cooked frozen food should not be defrosted & then refrozen. The state of the food should alter at each freezing Ie raw to cooked. If you froze raw meat you could defrost and cook. Then freeze the cooked item. Defrost the cooked item and heat throughly and serve.
What you describe above is absolutely fine. I'd be a bit more wary if e.g. chicken was involved (but would probably do it anyway!)
To my knowledge, anything that has just been cooked and cooled down is essentially sterile. Freezing it therefore poses no danger and on defrosting and prompt re-heating for immediate consumption it will be entirely safe.

On the contrary, something raw that is defrosted and left thawed for some time will be subject to the risk of microbes already present before freezing beginning to multiply, the level of contamination rises. If the food is now cooked then it will effectively become sterile and if then frozen the same argument holds as above.

Any food, raw or cooked, which is defrosted and left thawed for some limited time then refrozen will likely have increased levels of microbial contamination encased within it (introduction of contamination while defrosted) - on second defrosting it sets off on an elevated risk status - cooking will sterilise it again, rendering it safer, uncooked the risk to health is increased. Cooked food which has been frozen, defrosted and refrozen then only heated (no proper cooking) will induce acceleration of multiplication of microbes which may have been introduced at the first defrosting (near ideal conditions in the tolerable warmth) - hence the familiar recommendation against refreezing.
@cracker222

The science behind it is that, after each incidence of boiling killing bacteria off, fresh bacteria, floating in the air can land on the food as it cools. Fresh protein, wet surface, 37° C would be ideal growth medium - think petri dish.

Bacteria can divide every 30 minutes, so meat that has been cooling down and/or at room temperature for a number of hours, could be doubling or quadrupling the dose you ingest.

Freezing makes some bacteria *dormant*, not dead. So thawing gives the surface germs 'n' hours additional opportunity to multiply.

Reheating may kill the fresh growths of bacteria but botulism toxin is not destroyed by cooking temeratures. That is why people got sick and such warnings came into circulation.

Don't under-estimate decades of accumulated human exerience.

Assuming that you cook each time and that normal good, modern domestic hygiene practice and storage is observed throughout then I would think you run absolutely minimal risk of any ill effects.

The days of poverty, no refrigeration being available and shortages of food are happily over but back then the need to eke everything out under very poor circumstances led to serious problems. I would be far more worried about any presence of an animal in the home than of a build-up of bacterial toxins from what you are suggesting, although a public health inspector would always factor in and warn against the most unlikely doomsday scenario simply to cover his/her backside (that is also being modern). There is now some movement away from the exaggerated fears that have been induced and encouraged more recently because of the waste of food that results.

Enjoy your soups, stews, curries or whatever.
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Much sensible advice here. Many thanks all. PS - I'll let you know if I'm poisoned later this week when I have the next batch of the soup (thoroughly boiled!)

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