...start to taste bad? not with the special seal canisters, just regular jars.

Its bad before you even open it . Instant coffee Really.

From the get-go.
Instant coffee baaaaad.

There is no such thing as "good" instant coffee to begin with. It tastes bad , well, from the INSTANT you open the container. No method of storage will improve the repugnance of the stuff. And, get this: you went from bad to worse when you opted for, what I think, is the nastiest coffee brand available. Folger's in unacceptable at best. I won't drink it fresh brewed if it was free. I don't know why you are thinking of consuming instant "coffee" (yeah, sure it's coffee), but my suggestion to you is to un-switch to Sanka (hahahah, from and old TV commercial), and invest in the real thing. Really now.

From the very first second it's opened. Nothing like fresh brewed.

Yup...tastes bad from the second you open it.