When you open a tub of sour cream, there is often a watery liquid at the top. This is perfectly normal — that's whey, and it contains proteins and nutrients you might want to stir back into the ...

But imagine that with this in mind, you buy a gigantic 3-pound tub of sour cream from Costco and barely make a dent in it after a week. (Unfortunately, it might only stay fresh for about two weeks ...