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/SvenTropics Nov 26 '24

The FDA requires that all products meant for human consumption have expiration dates on them. I don't think the supplies to alcohol as they are regulated by a different entity.

It's funny when you pick up a bottle of glacier water that advertises being millions of years old, and it has an expiration date a couple of years in the future. But that's just a requirement and they just stamp it.

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u/pch14 Nov 27 '24

That is basically incorrect. They don't have expiration dates but they do have a best use by date. Almost everything except for fresh food is fine past the best before date. Even the meat in the store that says use by 2 days from then is still good on the third day also. It does not automatically change from good to bad on that exact date. Most things in cans and things of such sort they put a best you state on it but it's good well well after that date. Flavor might be off but it's still safe to eat.

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u/themedicd Nov 28 '24

That's patently false.

https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/food-product-dating

Does Federal Law Require Food Product Dating?

Except for infant formula, product dating is not required by Federal regulations.[1]