Brew Safely, Everyone

Clostridium_botulinum_01Recently, a group of people went to a church potluck dinner in Ohio. Of the 77 people who dined, one died, 11 had to be put on a ventilator to breathe, and another 17 fell ill. What happened? Well, the normal food safety rules that apply to restaurants and other places that serve food to the public don’t apply to church functions. As such, one of the cooks used the boiling water method to can (preserve) some potatoes. (Potatoes, a low-acid food,  should be canned using a pressure cooker.) Those potatoes then got used to make potato salad for the gathering.  Unfortunately, the potatoes were tainted with spores of the soil bacterium Clostridium botulinum and the pot luck attendees were poisoned by the botulinum toxin.

Why am I bringing this up? Because — as I’ve written about earlier — some homebrewers do something similar when storing their wort. Homebrewers who use the boiling water bath method of canning yeast starter wort, or use the no-chill method of cooling and then store the wort for extended periods of time, are running a similar risk of botulism.

I’m not going to rehash everything from the first two articles I’ve posted on this topic. I’m just adding the information above as further evidence that botulism is real and it can be lethal.

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BWJ Q & A (Botulism)

Clostridium_botulinum_01My recent article on botulism generated some discussion among homebrewers. I’ve gathered most of the questions I’ve been asked in the comments section and via email here. I’ve also added a couple that might occur to someone with an interest in the subject. The original article also answers some potential questions.


Background Information

Clostridium botulinum, the bacteria that produces the botulinum toxin, can grow in environments from 40–120 °F (4.4–49 °C) when the pH is above 4.6, the oxygen level is below 2%, and the water activity is above 0.85. (Solutions with 22 g of salt per 100 g of water or 67 g of sugar (sucrose) for each 100 g of have water activities less than 0.85.) The conditions for the growth of C. botulinum are met by boiled wort stored in a sealed container, but not beer.

Botulism bacteria can grow and produce enough toxin to kill a person in 3 days. And, the spores of C. botulinum are not killed by boiling. Commercial food packagers are required to heat low-acid foods (foods over pH 4.6) to 250 °F (121 °C) for 3 minutes to kill all the botulism spores. Boiling the liquid at 240 °F for 20 minutes, which can be done at sea level with a pressure cooker set to 10 PSI, and subsequently heating the food to above 185 °F (85 °C) for more than 5 minutes before serving are the guidelines given for home canners.

So, to be on the safe side, wort should be pitched the day after it is made. This way, the pH of the fermenting beer can drop below 4.6 and you will be safe. There is not a single case of botulism attributed to making beer in the normal manner. (Prison “brewers” have concocted batches of pruno that has been tainted, but these cases usually involve the use of root vegetables stored improperly before the beverage is fermented.)


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Storing Wort Runs the Risk of Botulism


Clostridium botulinum — the bacteria that produces the botulinum toxin, which causes botulism. (CDC photo in the public domain)

Botulism is a rare but serious condition that can occur due to eating improperly preserved foods. One homebrewing practice that is gaining in popularity may put homebrewers at risk for botulism — using the no-chill method of wort chilling and subsequently storing (unpitched) boiled wort in sealed containers for long periods of time.

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