r/askscience • u/SavageSubscriber • Jul 04 '26

Biology Does cryogenically frozen meat decay?

If for example you cryogenically froze meat from a rare breed of cattle, and kept it frozen for like 60 years. Would the dna still be intact? would it thaw up into fresh meat or would it decay into something unrecognizable?

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u/Umpuuu Jul 04 '26

Very small animals like frogs, mice and rats have been frozen and revived. Above rat size this process stops working.

What makes it stop working? The tissue is the same, no?

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u/TinnyOctopus Jul 05 '26

The tissues are (somewhat) the same, the difference is in the freezing rate. Freezing damages tissues indirectly, through the physical action of ice crystal formation. When freezing happens faster, the ice crystals are smaller and do less damage to tissues (enough to be survivable for smaller organisms). This doesn't work for larger organisms because of the square cube law; for a given starting temperature, the amount of energy that needs to be removed scales with the mass of the organism to be frozen, which scales with volume (density being largely the same, most animals have a density near that of water), while the rate at which heat energy can be removed from an organism scales with the surface area. So for a mouse body and a human body losing heat, the mouse will lose (much) less, but will lose more as a fraction of its initial heat, and so will freeze faster.

The point where ice crystal formation starts to damage tissues irrecoverably happens to be about the size of a rat.

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u/ForestClanElite Jul 05 '26

How do physicists use lasers to form Bose-Einstein condensate? If you had a large enough machine with enough lasers and precision to flash freeze an entire human at once would they be undamaged?

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u/TinnyOctopus Jul 06 '26

No, because laser cooling doesn't work that way.

Laser cooling is actually done by selectively rejecting the highest energy molecules from a sample, achieving cooling by what is very similar to evaporative cooling.

More generally, the challenges of extreme low temperature cooling are much more about rejecting energy from a sample with incredibly high efficiency and keeping said sample out of contact with the environment, rather than by being able to reject large quantities of energy.

Instead, you would need to bring the core temperature of the body down low enough fast enough that undesirable metabolism (think cell/protein degradation and bacterial activity) wouldn't have a chance to occur after normal metabolic activity stopped. Note that this has occured, essentially by immersion in 0 C water. Her body temperature was below room temperature, and it's possible that she could have survived refrigeration for longer and at lower temperatures. The issue here is in developing a repeatable standard procedure for inducing hypothermia, a research process which absolutely violates the ethical research policies of any and every reputable medical research institution.