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Jan 25, 2006 02:20 PM

does cooking kill bacteria? [moved from Home Cooking]

  • t

I did the dumbest thing--left out a baggie of chicken thighs to defrost and forgot to put it away when I went to bed. It was out about 8 hours. Still cool, but not cold. House temp was 68 degrees.

I'm going to toss it, it's only about $1.20 worth of chicken.

But does cooking kill any baddies that might have grown in it while between 40 and 68 degrees? The science part is what I'm looking for..Have checked other posts and they range from 'go ahead and cook it' to 'no way', but no science. I checked out CDC website and they were not clear as to the science. They were discussing salonella, but mostly in uncooked eggs.

Food Scientists out there?

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  1. No food scientist here, but I have "enjoyed" the Bad Bug Book at the link below. Lots of info. I believe that although heat will kill most bacteria, the toxins they may produce, may NOT be killed by heat.

    BTW, I leave stuff out overnight to defrost all the time, on purpose.


    4 Replies
      1. re: danna
        bruce in oakton

        I grew up in New Zealand in the 1940s and 50s. Until the late 50s MOST people did not own a refrigerator or the item Americans quaintly referred to as an 'ice box'
        My parents had a cupboard on the shady side of the kitchen with a mesh-covered window frame on the outside wall. In addition, all shops closed on Friday night and nothing could be bought until Monday with the exception of a couple of perishables such as milk and possibly eggs. The meat for Sunday's roast had to survive unrefrigerated in these circumstances and, in fact, its cooked leftovers were still consumed in various ways during the week. Meat was mostly Beef, Lamb or Veal - Pork tended to be eaten only in the cooler months and because of the absence of factory farming, chicken was an occasional treat.
        Butter was always soft; if jam grew mold you just scraped it off. Meat fat was poured off and saved in cans, in the aforementioned cupboard to be used for frying.
        The summer temperatures were often in the 80s but I don't recollect anyone in my family (or anyone elses) coming down with food poisoning.
        When we finally could afford a refrigerator it was celebrated as a means of having really cold drinks and ice cream etc on hand first, and long term food storage second.
        As most people in the world have had to get along without refrigeration until about 50 years ago, one can only assume that the toxicity cited so often is due to the way the food is now produced and processed.

        1. re: bruce in oakton

          Thanks! Left 1 1/2 pounds of chuck out for approx. four hours at 68 degrees, and I think I’m going to chance it.

          1. re: bruce in oakton

            Criminy. Didn't see it was ancient.
            Never mind.

        2. It'll kill the bacteria (salmonella kicks the bucket at under 140º), but it won't do a thing for any toxins that may have ensued from bacterial growth. However, my choice in this case would be to go ahead and cook'em, but then I'm the kind of nutcase that makes his own mayonnaise with raw eggs, too...if that is any help at all.

          4 Replies
          1. re: Will Owen

            For any other kind of protein I'd agree and cook but there is something about chicken that makes if go off so easily. Did it pass the sniff test?

            1. re: Homer J

              Btw, this is also true of grains, especially rice. Bacillus cereus is a major cause of the food poisoning people assume is from flesh but is actually from grains that have been left out too long at room temperature and allowed spores to produce toxins that will not be deactivated upon recooking. But a lot of people assume it's the meat that caused them to get sick when it was something as innocent looking as fried rice....

              1. re: Karl S

                I'm sure you are right but I cannot tell you the hundreds of times I have eaten rice that was left out over-night with no ill effects.

              2. re: Homer J

                I didn't sniff it- I've already tossed it.

                Just wondered about heat and toxicity.

            2. Any bacteria will likely start on the outside and work its way in as the meat defrosts so simply rinsing the piece of meat can wash away the surface toxins. I've watched other home cooks prepare chicken straight out of the package and that worries me.

              2 Replies
              1. re: D.T.
                Brian Lindauer

                Actually, the USDA recommends against washing raw chicken because it doesn't do anything except spread bacteria to other parts of your kitchen. See the Cooks Illustrated link below.



                1. re: D.T.

                  To paraphrase Jacques Pepin, there's no sense washing chicken...any bacteria that can survive a 450F oven for 30 minutes deserve to live!

                2. IMO, $1.20 isn't worth the pain and suffering you'd experience if you did get sick. I left some cooked eggplant out a few nights ago (see thread below) and am still hesitant to eat it, tho I'm sure it's a lot safer than uncooked chicken.

                  1. And still all you got was a bunch of "this is how I feel posts." My favorite is the poster who is upset with home cooks that make chicken right out of the package, as if rinsing under cold water does anything to kill pathogens in chicken. Chickens should, never, ever be rinsed before cooking.

                    Here's your science. All those organisms are killed when exposed to 141 degrees F for one minute. Since you're cooking your chicken at a much higher temp for a much longer period of time, your food is safe. Bacteria love temps between 40 and 135. There are good and bad bacteria and they die at higher temps and may go dormant at lower temps. Beware of cooked food that is cooling down as bacteria can again be breeding. If you intend to refrigerate leftovers, you want to get them below 40 degrees ASAP so that the bacteria has as little time as possible to reproduce. Leftovers reheated in excess of 141 degrees F for more then one minute will again kill any pathogens. Foods with a low pH (high acid content) are also safe as bacteria cannot exist in that environment.

                    You are smart to be concerned about food safety. Be conscious but not paranoid. Refrigeration is a very modern invention and mankind did pretty well for centuries before it existed.

                    3 Replies
                    1. re: dk


                      Yes, I tend to be a little casual about popping my leftovers in the fridge right away. (I like the idea of using an ice water bath to cool them quickly, but alas, no icemaker!)

                      Thanks for your post which shows me I need to be using my Polder themo to read reheat temps. I mostly nuke to reheat and need to be maintaining the 140 mark for a minute, so I'll pay attention to that.

                      Much obliged!

                      1. re: dk

                        Yes, and I agree the chicken in this particular case would almost certainly be perfectly safe, but earlier posters who mentioned that killing the bacteria does not necessarily destroy any toxins that may have been produced by those bacteria are also correct. However, for that to be a problem the bacteria must have had time to multiply and build up the concentration of toxins, which is extremely unlikely in an overnight defrosting (something I do all the time, and have [so far] survived).

                        1. re: FlyFish

                          Indeed. Which is why you can't just leave raw chicken out on, say, a 90 degree day for 12 hours, and then just cook it, on the theory that the cooking will kill all the bacteria anyway.

                          A rather important question of science, that.