SSIA.
Thanks,
Rob
It depends on the type of food and the types of bacteria that it contains, but generally you don’t want to eat anything that’s been in the “danger zone” of between 40 degrees F and 140 degrees F for two hours or more. Some types of bacteria can double in quantity within 20 minutes. I’ve heard that a turkey can grow enough bacteria to make you sick within 45 minutes.
But here’s the real question. The turkey comes out of a 350 degree oven (guessing that’s a realistic temp). There shouldn’t be any live bacteria in that bird (or is there?) I’m wondering how the turkey all of a sudden becomes a germ incubator. Is my household air loaded with perilous bacteria that are just waiting to land on a warm delicious foodstuff? What gives?
Yes, food safety rules are usually given as no more than two hours between 40F and 140F. Some sources say up to four hours, cumulatively. IIRC, the food safety certification exam in Illinois says two hours.
(This said, I grew up in a family that routinely left food to cool on the stove overnight. None of us ever got noticeably sick from it, and I continue to eat food that’s been left out without a second thought, but I would not recommend this and you are taking a slight risk every time you do this.)
What about when you reheat food (in my case usually its pizza slices) that got left on top of the stove for an afternoon? I’ve never suffered any ill effects.
The turkey that comes out of a 350 degree oven is 350 degrees (if it were, it would be burned to a crisp). According to my recipe, the turkey is done when the breast reaches an internal temp of 161 degrees (and the drumsticks are about 180). The presence of stuffing in the bird can be an incubator of death, or if brought to a safe temp, lead to a dry, nasty bird. This leads Alton Brown to proclaim that stuffing is Evil. That said, I was referring to food that presumably was properly cooked in the first place. Also, will reheating it render it safe again?
Thanks,
Rob
Actually, yes. Most of them are harmless, though.
Let’s say the turkey comes out with an internal temperature of 160 degrees. You’re right, that’s enough to kill most live bacteria. In twenty minutes it will cool down enough that newly introduced bacteria can survive and multiply.
Where does the new bacteria come from? The cutting board, the knife you use to carve the turkey, your hands, etc. Those things may be clean, but they aren’t sterile.
Yes, there are airborne bacteria. There are also bacteria on your hands (come on, no one really carves a turkey without touching any of it at all, do they?) and knives and forks and cutting boards and the hands of people coming in for “snitches”. There also may be some bacteria in the bird - cooking reduces the live bacteria to safe numbers, but it doesn’t eliminated them altogether.
Finally, some bacteria which may indeed be killed in heat also release toxic chemicals which may make you sick, which is why it’s not a good idea to leave a turkey out for a few hours and then think it’s safe again when you heat it back up. The bacteria may be dead, but the endotoxins can still make you wish *you *were dead.
Edit: D’oh! I type too slowly, sometimes!
160° in the interior of your turkey isn’t nearly enough to kill all bacteria, though it will kill a lot. There are plenty of heat resistant bacteria and spores that will happily start regrowing once the bird cools down.
And cooking won’t necessarily make contaminated food safe. In particular, staph (bacteria that’s on your hands and gets on everything you touch whether you like it or not) happily grows on food at room temperature. It doesn’t make you sick by infecting your digestive tract, but it produces endotoxins which can cause nasty food poisoning at high doses. The staph bacteria will be killed by reheating, but the endotoxins won’t be destroyed and can still make you sick.
There are other toxins and pathogens which can be destroyed by cooking, so thorough reheating of leftovers is still a good idea.
Overall, though, food safety regulations are very conservative, to the point of nearly eliminating food poisoning cases in a large restaurant that serves hundreds of thousands of meals to people with potentially weak immune systems.
If you’re more cavalier at home (and I certainly am) you’ll probably be fine 99% of the time. That’s not a big deal for a healthy individual – you might have an upset stomach once every few months. But in a restaurant setting, 99% isn’t good enough – that’ll lead to thousands of cases of food poisoning, and some of those are going to be very serious. A mild case of food poisoning isn’t a lot to worry about for a healthy adult. But it can be life threatening for Grandma, who’s already in poor health… So the food service industry is absolutely right to be as careful as they can.
4 hours, according to the 2009 FDA Food code.
There is also a “margin of error” of 2 hours, so the turkey in question should be eaten, cooled to 41˚, or through away within 6 hours after cooking.
Cite: http://www.fda.gov/Food/FoodSafety/RetailFoodProtection/FoodCode/FoodCode2009/ucm189169.htm
I always leave stews and most soups sit on the stove overnight to cool off (and for the flavor to intensify) after they finish cooking. It could be 12-18 hours before I stick it in the fridge.
Of course the key is that they have just finished cooking and there isn’t likely much life left inside the pot that has survived the cooking process well enough to settle down and have kids.
According to my microbiology teacher, this isn’t a bad idea IF you’ve had the soup/stew at a roiling boil for 10 minutes or more with the lid on before you turn it off and walk away. Don’t take the lid off! Her reasoning was that it essentially turns your pot/lid into an autoclave, and it will kill enough pathogens to be considered sterile until you remove the lid. Take the lid off for even a second, though, and you’ve broken the sterile field and potentially contaminated your stew with airborne pathogens.