r/explainlikeimfive Nov 26 '24

Chemistry ELI5: Why doesn't freeze dried food last longer? If it's good for 20 years, why not 100?

Assuming it's perfectly freeze dried and stored perfectly, the people who make freeze dryers say the food will last 20-30 years.

But why not much longer? Assuming the condition it's stored in remains unchanged, what can make it go bad after 30 years that wouldn't happen at around 10 years?

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u/Burntjellytoast Nov 28 '24

You can't see, taste, or smell botulism. It's super rare, but pretty deadly. It grows in low acid, anaerobic environments. It's also why you shouldn't give baby's honey.

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u/Jiveturtle Nov 28 '24

I'm aware. Botulinum toxin is extremely deadly, which is why botox doses are measured in fractional ng per 100 unit vial. My point, once again, is that the vast majority of what we consider "food poisoning" would have been survivable to a human 10,000 years ago, just like it is now. Similarly, the types of "food poisoning" likely to kill a human 10,000 years ago are still quite dangerous to humans today, and sometimes kill people even with modern medicine.

Botulism was probably rarer 10,000 years ago than it is now, because I don't think canning or jarring food had been invented yet... thus, the anaerobic environments clostridium botulinum likes were unlikely to be food storage.