it decomposes much faster
Because it can spoil or get mold.
To keep germs from growing and multiplying
The cast of Refrigerate After Opening - 2010 includes: Jennifer Bonior as Girl in Freezer Jes Mercer as Lucy
After opening, yes.
I would suggest you refrigerate the opened container. If it was in the refrigerated section when you bought it, keep it refrigerated. If it was not in the refrigerated section, check the label for instructions like "refrigerate after opening". Absent those instructions, refrigeration would probably help protect flavor even if food safety might not be an issue.
No you do not need to refrigerate extracts after opening. Such as Vanilla or Almond extract. They are perfectly fine to be stored in the cupboard and often mix better when the other ingredients are more room temperature as well.
Because it needs to be refridgerated
Asking different restaurants if they refrigerate ketchup and mustard there is a difference of opinion on that. However, all through the years I never refrigerated ketchup and it never said you had to on the bottles. Now they say refrigerate after opening. I don't get it.
You can freeze it or refrigerate it.
Yes. It really should have been refrigerated before opening, too.
Read the label on the bottle. If it doesn't say refrigerate after opening, the answer would be no.