Make food go bad
Ah shit my burrito's half mold...eh fuck it

would also love for that rotten stage of food to fuck you up a little bit a la a check-for-vomiting or a temp stat reduction (or even just an ambient message telling you That Tastes Like Mold). realistically eating the bar pizza someone left out 5 days ago is gonna make you feel some kind of way

I agree with Adam on how processed the food is. I also don't see the benefit of this. It might be realistic, but this is a game and food only has a tiny positive effect to start with. It will make catering more annoying to arrange. If mold is only visible when looking or through scrutinizing, it will add tedium. If it's impossible to know before tasting/eating something whether it has mold, it will make it feel like a game of chance and discourage people from eating anything they didn't make, catered or not.

The direct benefit to the game is two fold:

1) More nuance is fun, maybe even make catered food last longer based on ingredients to encourage the use of these items more
2) Less items taking up space on the MOO. I can't tell you how many discarded 1+ year old burritos I have spotted just lying in empty rooms taking up item space on the server.

Calling looking at some tedious is a bit silly. Ever look at your food before you eat it? The food already has a describer for how touched/untouched it is, so it really doesn't change much on the "omg I have to look at my food now???" scale.

To be clear, I'm not suggesting something goes bad over night here. Just like after a week of sitting out things should start to degrade in quality fast, then turn to fly-covered goop, then disappear entirely as items.

Ive found pristine sandwiches in the middle of nowhere in the badlands.