Why are shelf stable food items (like sauces, broths, etc) recommend to be used within a few days after opening? Do they actually go bad?

Question

I tend to keep condiments and things of that nature for a very long time in my fridge even though most Google searches say use within 3-5 days after opening. How can a sauce or can of broth or any other shelf stable thing last for months, if not longer, in my pantry, but if I open to use it for a few seconds and put it in my fridge it’s supposed to be used with if a few days? I’m talking anything from pickles to mustard to broth. All of those items seem perfectly fine in the fridge even after weeks or sometimes months.

In: Other

Answer 1

When they are sealed, they are sealed clean. But once you open, outside germs and mold spores can get in and grow quickly due to lack of competition.