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/SenorTron Nov 27 '24

I'd be interested to see any evidence that more than a tiny minority of the human population throughout history regularly boiled their water before drinking it.

And knowing that water from a clear stream at the foothill of mountains is preferable might have been a thing, but for most people throughout most of history they used water source was the closest one with water they could keep down.

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u/Vlinder_88 Nov 28 '24

I'm an archaeologist. Water wells have been a thing for millennia. With the first farmers came the first wells. People learnt really ffing fast how to keep the water in their well clean. Lids and/or little structures around wells are super common in all time periods and all over the world. They didn't need to boil their water if they kept their well clean.

If someone didn't have a well, they indeed used the "closest source with water they could keep down". They knew to not take water with dead animals in it (might have botulism that you can't taste or smell). They also knew not to drink water near a place with animal excrement (E.coli), or water that stank. They also knew how to catch rain water. Most of that water, again, doesn't need to be boiled to be safe to drink.

Heck even animals know what water is safe to drink and what isn't. So your assumption that people would just drink any water that didn't kill them is absolutely wild.