I left a fully cooked ham in a bag out overnight. It was refrigerator temperature when I took it out at 9pm. Our Seattle home was not heated; it was about 50 degrees last night. I found it at 6am and threw it back in the fridge, in case it was still good. I would cook it again and then use it with eggs or sandwiches. Would this be ok?

  • How was it protected? I.E. still sealed? I don't know if that makes a difference, but it may – mfg May 2 '11 at 20:06

It's probably even safe to eat without cooking again; the refrigerator is likely only about 10 degrees colder, and that generally translates to accelerating rates of spoilage (mostly growth of pathogens) by a factor of 3-5 or so. For example. at 10C (50F), E. coli only manages to divide once every 8 hours or so (see Ratkowsky et al., "Relationship Between Temperature and Growth Rate of Bacterial Cultures", J. Bacteriology, vol 169, p. 1 (1982) for a not-very-clear example of growth curves--I've seen these curves online, but unfortunately I tried and failed to find an easily accessible one this time).

It's almost certainly safe to eat with cooking (fully, to at least ~160 at the center), which would kill anything that managed to grow on the ham. The only thing to worry about with well-cooked food is whether bacteria or fungi have managed to produce so many toxic chemicals that the food will make you ill--and in this case, it's been too cold. (At those temperatures, not only is growth slow, but most anything is slow, including production of anything toxic.)

So I'd say--cook away, enjoy, and don't worry about it.

P.S. I have in practice eaten ham left out at warmer temperatures for longer.

Edit: In response to a comment about bacterial toxin production, I want to reiterate that colder temperatures slow down metabolism of just about everything, including toxin production. This is because, at a basic physical level, reaction rates are governed by the Arrhenius equation which translates, for simple reactions, to a doubling of reaction rates for ~10C increase in temperature. Of course, organisms like bacteria have more complex interactions, but this still gives an order of magnitude estimate. Furthermore, research has been done on production of bacterial toxins. For example, Skinner & Larkin (J. Food Protection vol 61 p. 1154 (1998)) wrote a paper called "Conservative Prediction of Time to Clostridium botulinum Toxin Formation for Use with Time-Temperature Indicators To Ensure the Safety of Foods", which gives, for food innoculated with the bacteria, a time-to-detection-of-toxin of 2-3 days at 10C. In fact, they did the research because food storage at open-face refigerators in stores often allows products to get up to as high as 10C (at least as of 1998).

Similarly, in Bonventre and Kempe ("Physiology of Toxin Production by Clostridium botulinum Types A and B, III"), their 10-18C toxin line is flat for 24 hours at the baseline level before creeping up by a factor of 3 or so between 24 and 48 hours (figure 4).

These are just examples, but you find the same general trends everywhere because of the fundamental physical relationship between reaction rates and temperature.

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    What evidence do you have, daniel, that this is bad advice? I cited research on microorganism growth to back up what I said. Leaving your ham on the table during dinner for an hour and a half allows stuff to grow up more than overnight at 50F. Shall we throw out any food that sits out during a moderately leisurely meal? – Rex Kerr May 3 '11 at 2:58
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    @daniel - I don't think you understood the question. The question seemed to me to be, "I did something that violates standard food handling rules. Can I make an exception?" All you're saying is, effectively, "no no no no no!" without any evidence. If you want to keep yourself safe legally this is exactly what you should do. Otherwise, you need to look at the question more deeply to understand why food spoils. If you do not understand how the risks arise, then I agree, the only safe thing to do is adhere strictly to general rules. – Rex Kerr May 3 '11 at 14:09
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    @daniel - If you have any evidence or data to share--for example, come up with any scenario where the original ham could have been edible but now is not, backed up by some sort of research--then we could maybe resolve things. As such, since you are simply repeating your opinion and not giving any evidence for it, we'll have to agree to disagree. (And yes, I understand both safe food handling, sterile technique in the laboratory, bacterial growth pathways, and so on.) – Rex Kerr May 3 '11 at 19:35
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    @daniel - Growth rates of pathogens is not a mystery. You're acting like the entire medical research profession doesn't exist (not to mention food safety research). Maybe it's a mystery to you, but that's not a reason to get all frantic. Meat sitting out for 9 hours at 50F is not the same as meat that's been sitting out for 9 hours at 80F because growth rates are very different at those temperatures. Since you seem unwilling or unable to grasp this, there really isn't anything left to discuss. (Incidentally, if I pay for any medical bills, will you pay for all the wasted hams?) – Rex Kerr May 4 '11 at 13:01
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    @daniel The "four hours in the danger zone" rule isn't hard and fast; it's more of a rule of thumb. If you've ever eaten a tough cut of meat prepared at a modern restaurant, chances are it was cooked at 55°C for a few days. If done properly, the meat can be effectively pasteurized. The actual "danger" is a much more complex function of time, conditions, and not only temperature but more importantly the change in temperature over time. – ESultanik May 4 '11 at 16:58

This is a ham right? Not a bone-in cooked pork butt, but an actual cured ham?

This falls into the category I like to call "Things I personally would eat, but wouldn't feed to anyone else." Chances are it's fine. 80 years ago they'd have thought nothing of it, but in our modern bacteria-obsessed culture, a few hours sitting on the counter is certain death. It was cooked, it was cured, it's probably okay. Hell, I've eaten cheesecake that's sat out the same amount of time, and the food nazis'll have you putting those in the fridge before they're even cool (which I know the professionals don't do, since that makes them crack like the grand canyon.)

On the chance that it's not okay, I wouldn't feed it to anyone else. And if you're going to eat it, I'd eat it quick. It certainly doesn't have as much shelf-life left.

Edit: My usual harp is on cooking temperatures (the recommended ones are all too high for me), but bacterial growth is another sore point. People will tell you a side of beef stored at 36F for a week must be used, frozen, or thrown away, and they'll tell you that, if you dare to cook it, it must be cooked well-done. But a high-end steakhouse will store it for three to four weeks at the same temperature, and sell you the finest steak you've ever eaten (cooked medium-rare) for 30 bucks a pound.

Sure, you can get unlucky and a random wrong bacteria can land on your food, multiply, and cause trouble. That's why they make the rule, so you're going to be safe 99.9% of the time. Like eggs. Raw eggs are killers, right? It's estimated that 1 in 14000 eggs has salmonella contamination, but that means 99.99997% of the time, you're fine to eat them raw. Don't take foolish risks, but don't let paranoia ruin your enjoyment of food either.

  • It's notable that we don't cure ham like we used (though I still doubt that it's dangerous). – Brendan Long Jan 16 '12 at 1:49
  • @brendan: Well, we do, but this isn't that kind of ham. Still, in this situation, the curing we do do, plus being cooked, plus the house being cool, I wouldn't have any problem eating it. – Satanicpuppy Jan 18 '12 at 14:40

If the ham picked up anything like botulinus then the toxic waste products are not destroyed by re-cooking... so the ham would remain toxic.

So the safe advice would be to throw it away.

And from a self-preservation point, I can't possibly advise anything else.

However, ham is full of preservatives (that's why it's ham not pork!) and it's probably safe to eat as is... but it's YOUR risk and your should NOT feed it to anyone else without them accepting that they are doing something risky and (nowadays) unusual. Playing russian roulette with your health is YOUR call, playing it with your children's health (or yoru spouse's health) is emphatically NOT your call.

  • In most parts of the world Botulism is very rare (though still very dangerous). It should not form on correctly cured hams as they are very salty at surface level and should be quite dry. It also requires anaerobic (wet) conditions. So a ham in a cloth at 10°C is not an ideal candidate. I would not same the same about store sliced ham etc – TFD May 4 '11 at 11:19
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    Ham is typically cured with sodium nitrite, which has historically been used specifically to block botulism growth. Not that there is no risk, but that's probably not the primary bacteria to consider. That said, listeria, e. coli., salmonella, etc., all work in the same way (though their waste products aren't quite as deadly). They produce toxins that remain after the bacteria has been destroyed. – Ray May 4 '11 at 17:14
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    Botulinum toxin is denatured at 60°C; as long as that temperature is achieved for a sufficient period of time (or a higher temperature for a shorter period of time), the "toxic waste products" will almost certainly be destroyed. – ESultanik May 4 '11 at 17:39
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    @ESultanik: Botulinum toxin is actually one of the easiest to get rid of. Most protein toxins are far more difficult to inactivate and require food to be cooked to ash, or at least to a flavourless mass. Examples: E.coli O157:H7 encodes an SLT or STX which just starts to denature after 5 minutes at 95° C, diphtheria toxin needs to be subjected an autoclave or chlorine bleach to inactivate, and I'm not even sure what the parameters are for CdtB. All of these are capable of being produced by bacteria on the food, just not quite as fast as they are within the GI tract. – Aaronut May 5 '11 at 14:52

No. It is garbage. There is a chance that it might be okay, but given the nasty bacteria that could be there, and the less than stellar track record of US food producers in recent years, it is simply not worth the risk.

@mfg, no difference.

Throw it out.

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    What nasty bacteria would this be? This is a home environment. It was a fully cooked ham, so at that point it was essentially sterile. The only bacteria that would likely come in contact with it would be home based human host bacteria, which at reasonable levels will be fine and good for you. At 10°C, by the book raw meat takes 2 days to spoil (twice as fast as 4°C), as only a few types of bacteria can grow that cold – TFD May 3 '11 at 9:10
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    Could well be absolutely fine for that sort of short time, many people take ham sandwiches to work that end up in a more ideal growth environment for just as long with no major issues. If he is recooking it too, then that will kill off any bacteria that could be on it if done properly. – Orbling May 3 '11 at 20:39
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    @daniel That's nine hours at 10°C. Check your food hygiene tables, that is only twice the decay rate as at 4°C. So equivalent to 18 hours in the fridge, therefore not a problem. Yes in a commercial operation you would toss it out and sack the slacker whom left it out! – TFD May 3 '11 at 23:49
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    A professionally-trained chef's job is to ensure that people treat food carefully. It is unwise to advocate that people should go ahead and do risky stupid things that can severely impact their health. – daniel May 4 '11 at 0:02
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    I reverted your latest edit daniel. The sarcasm isn't really necessary in your answer. Besides, I voted for your original answer, not the sarcastic edit :P – hobodave May 4 '11 at 16:05

At home, If the ham was left out, I would be more concerned with its environment given these timeframes. Was it covered, human/pet/insect Traffic, was it handled/sliced, served or whole, etc. If it was fully cooked, uncut/unserved, covered, and at room temps, I would eat it and even serve it to family. There are other risks that exceed the risk of spontaneous spoiling in the first 9 hours, i'd bet there is a better chance you would choke on it than get sick.

If it was a business I'd toss it or give it away. I used to throw out foods I KNEW were ok, just because it looked or smelled funny. Only because I didn't want to even deal with any questions. Distractions usually end up costing more than materials.

FWIW, my2cents


Do not eat it. It will most likely have bacteria in it, making unsafe to eat.

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    Lots have things have bacteria in them that we eat, often deliberately, yoghurt for instance, it is not a blanket "issue". – Orbling May 3 '11 at 20:37

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