Does pasteurization of honey kill Clostridium botulinum?

The idea that honey should be pasteurized is truly odd. Honey has been used for centuries to dress wounds because of its antibacterial properties, and yet some people want to pasteurize it as if it might cause disease. Honey virtually never goes bad because it provides an inhospitable environment for most pathogens, yet some people want it cleaner.

Clostridium botulinum is a very common soil-borne organism that doesn’t cause problems for humans unless it is allowed to grow and produce toxins. This happens occasionally in low-acid (medium to high pH) foods that are not properly processed. Clostridium botulinum favors anaerobic conditions with a pH of about 4.6 or greater, so it sometimes is found in home-canned jars of fish, beans, mushrooms, and low-acid tomatoes.

Botulism spores in honey

As it turns out, the spores of Clostridium botulinum can survive in honey, but they can’t germinate, grow, or produce toxin in the highly acidic and extremely hygroscopic environment of honey. The spores just stay in the spore form. If we eat them, they go through us just as they would if they were stuck on a carrot or potato. The spores are everywhere and not a threat to humans with two exceptions—infants and individuals with compromised immune systems.

Very young children, usually during the first few months of life, have an underdeveloped intestine that sometimes allows Clostridium botulinum spores to grow within the gut and produce toxins. The condition is quite rare, but it most frequently happens after the ingestion of honey. The infant digestive system matures early and within a few months, the spores will pass straight through a child just as they do in an adult. Although the vulnerable stage is short, to be on the safe side, it is recommended that parents wait until a child is at least one year old before feeding honey.

Pasteurization has no effect on botulism spores

Some people believe that if the honey is pasteurized it will be safe to give to infants. Nothing could be further from the truth. Pasteurization does nothing to botulism spores. Nothing.

Both the actual Clostridium botulinum bacteria and the toxins it produces are easily destroyed by boiling for several minutes or by holding them at lower temperatures for longer times. The spores, on the other hand, are extremely resistant. Pressure cooking at 250° F (121° C) for three minutes will kill the spores, as will other combinations of temperature, pressure, time, and acidity. At standard pressures, it could take hours of boiling to kill them.

Honey is pasteurized at low temperatures

But honey is pasteurized at much lower temperatures. Most sources I found recommended heating the honey to 145° F (63° C) for 30 minutes. Some preferred 150° (65.5° C) for 30 minutes. One suggested that the temperature be brought to 170° F (77° C) momentarily. In this environment, Clostridium botulinum spores are going to take off their little t-shirts and luxuriate in the sauna-like conditions.

The only thing that pasteurization does to honey is destroy many of the nuanced flavors and aromas, as well as many of the phytochemicals, antioxidants, and nutrients. In other words pasteurization degrades the product yet provides no clear benefit.



  • Rusty, Thanks for a great article on Clostridium botulinum. Few people realize that many bacteria have spore forms that will not be killed by pasturization. It is a mystery why pasturization of honey is performed at all. Thank you for such a well written blog.

  • Great article. I wonder how many folks out there are scared of their shadow too? If we really want to become concerned, take a swab sample of our bathroom sink or floor and have an analysis done…bet there are much more dangerous spores and bacteria there than in honey…

    The spring flows are under way…remember to super up!!!

  • My guess is that honey is pasteurized to prevent it from crystallizing on the store shelves. Heating the honey to a certain degree does that too. I suppose someone thought why not pasteurize it while were at it so people who’ve grown up on pasteurized milk will think it’s safer.

    I’ve met people who think crystallized honey is honey that’s gone bad. Just about any product sold in a clear container has had its appearance artificially enhanced or has had a meaningless label put on it that gives it more appeal to the general public. So much in marketing is based on appearance, not facts.

  • Honey is pasteurized to prevent if from fermentation. Honey has yeast and yeast spore which may cause fermentation of honey which is not desirable. Moreover, the low treatment also help to reduce the moisture in honey.

    • Zeba,

      Properly cured and extracted honey will not ferment and does not need pasteurization; it is one of the properties of honey that mankind has marveled over for centuries. Mold and yeast spores cannot germinate in properly cured honey because it is too hygroscopic. The high sugar content literally sucks the moisture away.

      If your honey is fermenting, I suspect you are mixing too many uncapped cells in with the capped ones. Too many uncapped cells makes the honey watery enough to allow mold growth, fermentation, and/or other types of spoilage. The rule of thumb is that a maximum of 10% uncapped cells be used, but it depends on how watery the uncapped cells are.

      For a more accurate assessment, use a refractometer to measure the moisture content of your honey.

    • Jesse,

      The sample size is way too small to give statistically significant results. Not only that, all the honey came from a single source “donated by a large honey producer” and apparently it was all canola honey. This does not provide any kind of cross-section of all honey.

      Many people complain that the worst aspect of heated honey is loss of flavor, but loss of flavor is not addressed anywhere in the paper.

      Also, kind of creepy is one of the possible reasons they give for the increased mineral content and antioxidant activity: “Diatomaceous earth (used for filtration) may increase the concentration of minerals and antioxidants in honey.” Really? I would rather not eat diatomaceous earth.

  • Hello,

    My son has issues with yeast overgrowth in his intestines, which among with GI issues manifests itself as mild ASD symptoms, obsessive behaviors. It is only after a 2 month candida diet that I see honey may be a potential OK sweet food for him. A study performed in 2011 indicates there’s potential of specifically lavender honey in combating the yeast candida krusei. With all the “fake” honey talk out there, would you be able to recommend a maker of real lavender honey? Also, given yeast issues I am concerned about clostridia, how common is this organism in honey?

    • AR,

      I can’t give medical advice, and I don’t know anything about your son’s condition. If you want lavender honey, I recommend you buy it from a local beekeeper or a farmers market and ask the beekeeper how much lavender is in the lavender honey. It will vary. As for Clostridium botulinum, the spores are very common in honey and pasteurization won’t kill them.

  • Thanks for the nice effort. I’ve been asking myself if honey source is genuine and lab-tested then found to be free from botulinum spores, is there any good reason to still advice against its use in infants?

  • Hi Rusty, thanks for the article. I am making syrups with honey instead of sugar and wondered if there is a risk of botulism when I combine 50% heat treated elderberry juice, or mulberry juice, or rosehip juice with 50% unheated honey?

    I’ve been told by friends that this is potentially a cause for botulism, and that I need to boil the honey mixture which would be a shame, as per your comments above… I just wondered whether you had any experience in making fruit honey syrups. It would be great f you could me out or point me in the right direction… Thanks in advance… Robin

    • Robin,

      I wouldn’t give honey in any form to children under one year, if that’s the question. If it’s for adult (>1 year) consumption, it would be safe. Honey is acidic, elderberries are acidic, rosehips are acidic, and mulberries are slightly acidic. Since botulism can’t grow and produce toxins in an acidic environment, the spores would remain harmless.

      I don’t know where your friends get their information, but boiling honey would not kill the botulism spores. To actually kill the spores, you would have to pressure cook the mixture, the way you would if you were canning something like green beans. See the above post, “Pressure cooking at 250° F (121° C) for three minutes will kill the spores, as will other combinations of temperature, pressure, time, and acidity. At standard pressures, it could take hours of boiling to kill them.”

      If you have any doubt, add a couple of tablespoons of lemon juice. Better yet, check out the USDA website for food safety. You can also buy a pH test kit.

  • So, cooking with honey is adviced against for infants. Good to know. Better to use apple syrup/molasses then.

  • I have some honey that came out of my wall. It has some contaminants in it from the insulation, bird nest, and many years of being open to the elements. Should I boil the honey? I can see some black flecks in it that I didn’t get out by straining it. Thank you

    • Ann,

      Boiled honey isn’t very good. Even heating honey slightly can ruin many of the flavor components. In any case, boiling won’t get rid of the insulation or black flecks. If it were me, I would toss it.

  • Is raw honey safe for dogs with allergies…some conversation about the botulism risk among owners…

    • Shirley,

      This is a confusing question. For one thing, allergies and botulism don’t seem to related in any way I know about. When botulism spores are allowed to grow and reproduce, they make a poisonous toxin. Really, I think feeding honey to dogs is a question for your vet.

      Secondly, the term “raw honey” is used a lot, but it doesn’t really mean anything. Raw is usually the opposite of “cooked” and no one cooks honey before they eat it. You can pasteurize honey by heating it gently, but that will not destroy botulism spores. To destroy the spores you would need to pressure cook it, which would ruin it.

      Basically, raw honey and regular honey are the same thing. But the word “raw” implies that it is somehow unfinished, which is certainly not true: it’s just one of the many myths and half-truths surrounding the subject of honey. Honey straight from the hive is not raw in any way—is is honey-ready-to-eat.

  • I am glad that I did not know about the dangers of honey, 53 years ago, or my daughter may not have survived. She could not hold ANY foods down, it either came back up or went straight through. After four months the DR said give her 1 oz of honey to 7 oz of water, as many times a day as she will take it. Seven months (?) later she had her first solid food-mashed peas and potatoes. Thank God for my ignorance and God’s perfect food.

    • Fred,

      I think the dangers of honey are overstated. Cases of infant botulism are very rare, and I read recently the most cases come from breast feeding. Also, the time frame is exaggerated. In most cases, the infant is safe at about 6 weeks. All of the recommendations are written to be fail safe, which is fine, but it also means we shouldn’t panic. Remember that whole generations of us were raised on cow’s milk laced with honey, also known as homemade “infant formula.”

  • What makes botulism deadly is that it is a poisonous toxin it is not a spore issue at all. No amount of heat will get rid of it.

    • Julia,

      1. Yes, the toxin is the part that is deadly. It is produced from bacteria that come from the spores. So without spores, there is no toxin.
      2. Heat will deactivate the toxin, and high heat under pressure will kill the spores. Boiling for several minutes is enough to deactivate the toxin. Heat under pressure (pressure canning) will kill the spores.
      3. It is very much a spore issue and there is an amount of heat that will get rid of them.

  • How much lemon juice should be added to say a deciliter of honey to lower the pH enough to kill the spores? Looking into medicinal uses, well, starting to. Have had a wound that the doctor used Manuka honey on, worked wonders, but it costs a lot.

    Our heather honey has been tested to be almost as good, but you’d want to get those spores out if any are present. It seems that pressure cooking destroys a lot of the good compounds though, so looking around for the pH levels needed.

    • Mike,

      You don’t want to add lemon juice or any other liquid to honey because it can make it ferment. Don’t worry about the Clostridium spores unless you are going to feed the honey to infants. The spores can not produce toxin in the acidic environment of honey. Honey for medical uses is best used straight out of the comb with no tampering. See this post for how honey works as an antimicrobial.

  • Hi Rusty,

    I’m just wondering, is it possible to get honey that is free from botulism? I found out that there is one brand claims that their honey is free from botulism and even has a lab result to back up their statement and also market their product for an infant. However, where I come from, lab result is “manageable” as long as there is money under the table.

    Thank you!

    • I would be skeptical because botulism is everywhere, in soil and water and on plants. I don’t see how honey could be botulism-free without pressure-cooking it, which would ruin it.

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