We have all been there – eyes bigger than your stomach when ordering pizza, resulting in a good few slices left over. You can try and cram it all in your stomach but sometimes it gets the better of you, and you have to face defeat until the morning. You put the pizza back in the box, and slump off to bed into a 12 hour pizza coma, and maybe before you drift of to sleep you wonder how long pizza can sit out for before it goes off…
According to the United States Department of Agriculture (USDA) you shouldn’t eat pizza which has been left out over 2 hours. This is because beyond this point the bacteria population can double every 20mins, meaning that the risk of getting food poisoning is greatly increased. Your left over pizza is ok to eat the next day however, if you have put it in the fridge once you have stopped eating it.
You would like to think that the USDA know a thing or two about food, and although they do get some things wrong, they shouldn’t get something as simple as rate of bacteria growth wrong, right?
Well they are right. Using E.coli as an example (because it is a pretty common food borne pathogen), it takes 15-20mins to double its population. So it looks like 2 hours is the limit in the eyes of the experts.
Generally speaking, research will trump the anecdote every-time, but the experience of the population cannot be ignored. Doing so would be bad science!
Time and time again the lazy student, or forgetful pizza lover will leave a pizza in the box over night, and reheat what’s left for breakfast, or even lunch with no ill effects! I’ve been there a number of times myself (both as a student and pizza lover), so I know first hand that the pizza left over night can be fine to eat, and usually is.
So, despite the USDA’s recommendations, it look like pizza can sometimes sit out over night and still be fine.
Truth is, there are a number of factors to consider aside from the length of time the pizza is sat out. You need to consider how much bacteria is on the pizza to being with, the temperature it has been left out for, and what toppings on the pizza (meat toppings are worse).
If you want to play it safe, then put your pizza in the fridge once you have finished, and you can eat it the next day. The recommendations say do this within 2 hours, but there will be some play in that really. Having said this, if you have gotten the pizza from a reputable pizza place (and so know it has been hygienically prepared/ cooked properly) then it will probably be fine for breakfast the next day if its left out, but any time after then and you are pushing your luck.
This Youtube video will give an overview of the information found on the article tab. If you want to know more about the topic, or want to see where the information came from, have a read of the article after you watch the video.
Officially, pizza shouldn’t be left out for more than 2 hours, but the risk of food poisoning from leaving it out overnight is very low, especially if you re-heat it properly.