I just threw out half a 48 ounce container of Breakstone 2% Cottage Cheese that I bought recently @ Costco. It had soured and broken down. The expiration date on the bottom was May 20th. I called Kraft and they said the expiration date is only for unopened product and that once you open it the shelf life is about 5 days. When I buy milk and other highly perishable foods I look @ the expiration date and figure that's the earliest it will spoil, opened or not, as long as I keep it well refrigerated (always under 40F.). There is an indication on the package that states "for best quality use within 5 days of opening. I think this caveat should be declared on the date stamp. If today was May 15th I would not feel cheated but this is 18 days before the stamped expiation date. Is this product blanketed with nitrogen or some other preservative? Regardless, no more 48 ounce containers for me.