Let’s see. If I’m selling food, I have motivation to print a “use by” date on the product that is very conservative.
- the sooner consumers throw out my product, the more I will sell
- I can reduce the risk of someone suing me because they claim they got sick eating the food before its “use by” date
If “use by” date isn’t regulated, I’d would guess that manufacturers’ “use by” dates are much sooner than reality.
As an aside... I love fermenting my vegetables. Especially super sour dill cucumbers. The longest batch I have done is two years. Yum.
As for canned food and mres... I have eaten 10 year old of each. Mostly odd ball canned vegetables. Toss them in a pot of chili and they’re good to go.
If you boil water for pasta you can freeze the boiled water to use later. It lasts indefinitely...