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I made and baked a ground beef lasagne for dinner. After eating I forgot that I left the remaining lasagne out on the worktop. It was covered with foil during the time it was left out. It was still warm when I put it in the refrigerator. But it had been on the worktop for about 2 hours and 45 minutes.

It is cold outside where I live but the central heating was on so it would have been at room temperature.

Do you think it would be unsafe to reheat it tomorrow? I don't want to eat it but my parents do. They think it will be fine. I don't want to make them sick.


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marked as duplicate by Aaronut Apr 20 '13 at 12:22

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To whoever downvoted this question - please be so kind to state a reason for doing so. The poster had legitimate (though overblown) concern and deserves a real answer. –  ddimitrov Jan 27 '13 at 4:24

1 Answer 1

These are the USDA recommendations for raw ground beef - it says that after buying it from a store (assuming the store follows the sanitary norms), you can leave it non-refrigerated for up to 2 hours. My guess is that this is where your worry is coming from: http://www.fsis.usda.gov/fact_sheets/Ground_Beef_and_Food_Safety/index.asp#25

On the other hand, cooked food is different from raw food - most of the bacteria that causes spoilage has already been killed. The bacteria that causes diseases (botulin, etc) have also been reduced to practically zero. It should be safe to leave cooked meat dish for at least 6-8 hrs (otherwise, how can we have these 2-3 hrs diners in fine restaurants?)

Keep in mind that the official recommendations are what will definitely keep you safe, given the worst outside conditions. If you have central heating and you are able to post in this forum, in all likeliness, you leave in cleaner environment than 95% of the world, so you may as well take advantage of the safety margin and not let a good meal go to waste.

PS. I regularly have this kind of conversations with my wife, so I know where are you coming from. I would recommend reading more about food safety and general biochemistry of cooking - in particular "On food and cooking" is a great book (some day I am really going to finish it :-)

PPS. As much as we would like, food-safety (and any kind of safety for that matter) is not exact science - there is always some risk, even if it is very low. See also: http://en.wikipedia.org/wiki/Zero-risk_bias

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I usually leave lasagna out an hour or two, just to cool it down enough to put it in the refrigerator without endangering everything else in there. (Lasagna retains heat well.) –  Steve Jan 27 '13 at 6:33
While cooking food does kill many of the pathogens inherent in the food, new microfauna will enter the food from the air, and the cooking does not eliminate all toxins that may have been produced prior to the cooking. Also the most perishable ingredient in lasagna is likely to be ricotta for many recipes, not the meat. That said, there must be a balance in all things. Putting hot food into the refrigerator can raise the temperature of the other food in the fridge which is also not good. All in all, for healthy adults not otherwise at risk, I would agree the lasagna is probably fine. –  SAJ14SAJ Jan 27 '13 at 11:54
@SAJ14SAJ: well, that's how I always saw people aging ricotta at home... although you are right, in that case you often add quite a bit of salt or some culture. Anyway, when you buy fresh ricotta at a market it is definitely not refrigerated (at least in Southern Europe, I doubt that is true about the US) so I am definitely positive that 2h45' at room temperature is not that big deal. –  nico Jan 27 '13 at 16:11
@rumtscho - it takes time for the fridge to cool everything back down, though, and the temp has to rise first for the thermostat to notice and kick in. (My fridge is quite crappy so while it can just about keep everything cold enough as long as no-one leaves the door open for too long, if someone puts warm food in it will be HOURS before it gets back to an OK temperature). –  Vicky Jan 28 '13 at 16:30
@rumtscho I believe that is true for small volumes of food, but I wouldn't put two gallons of fresh hot chili or stock in the fridge, either. The compressor has a limited capacity, and you will get local hotspots while it works--it is not instant after all. A hot lasagna has a large mass of heat, and warm the items near it before the compressor has time to get the entire space back to the set equilibrium temperature. So with respect, I don't think it is nonsense. –  SAJ14SAJ Jan 28 '13 at 17:17

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