That won't work. The rate at which different foods spoil after they're opened varies dramatically. Foods with a lot of salt in them, for example, stay good for

That won't work. The rate at which different foods spoil after they're opened varies dramatically. Foods with a lot of salt in them, for example, stay good for a long time, while my carrot juice spoils within days of opening it. Not to mention, until you break the seal, what are those bacteria using for food? I just write the date on things with a sharpie when I open them. A technological solution here seems to me to be more likely to complicate than simplify.