Past expiration dates? Fuzzy berries? Old leftovers? Some of it can be eaten, the rest not so much.
In a place where we throw out 133 billion pounds of food out every year, those of us in the United States might be seen as a bit over-eager when it comes to tossing our edibles. And although it's a tragedy, especially given that so many people in this world have so little to eat, I can see how we got here. Among other things, food is cheap and abundant; marketers and the media promote beautiful picture-perfect food, seducing us into buying too much and trashing it once it's less than flawless; and this one's hard to deny – most of us know the abysmal consequences of foodborne illness.
Fortunately, there are wafts of change in the air. Ugly fruits and vegetables are the new supermarket darlings; people are becoming more aware of food waste; and more of us are learning that older foods can be revived or used in delicious ways.
Even so, even the most stalwart of anti-food-wasters does not want to eat a rotten piece of food and suffer illness. Which is why this video from the American Chemical Society does a good job of addressing some of the more basic food safety concerns, like can you eat past the date printed on the package? Can you eat moldy berries? How about moldy cheese? (Spoiler: Yes, no, kind of.) It also goes into some of the science behind rotting food, which is pretty interesting in a know-your-enemies kind of way. Bon appetit!
For how to avoid having old food in the first place, see: 15 ways to avoid food waste