Just butting in here as a newbie on this interesting thread.

Sour cream: how do you know when it's gone off?

Seriously?!

I bought a tub 5 days ago for use with some nice avacados, and have most of the tub left. No 'sell by' date on the carton of course.

Any advice?

Any ideas for other uses? (Culinary only, please).

Garlic butter: excellent on a steak and as a snack on those slightly salty Ritz crackers. Any other ideas? (ditto above).

Thanks in advance.

Stroganoff for the sour cream, as to when its gone off I usually sniff anything I think may be a bit dodgy or look for a change in colour. I think 5 days should be fine.