The first case of food-related botulism recorded in medical literature occurred in Germany in 1735 and was traced to uncooked fermented blood sausage. Food safety history guru (and pretty decent margarita recipe-developer) Carl Custer pointed out in an IAFP workshop that botulism concerns (and regulatory responses) go back further than that. In the 10th century, Emperor Leo VI of Byzantium prohibited the manufacture of blood sausage because of repeated illnesses leaving folks paralyzed and dying not too long after exposure. Botulism (derived from botulus, the latin word for sausage) is pretty nasty.

The spores, found fairly commonly in soil, germinate and outgrow in anaerobic conditions (like partially-fermented sausages, under processed canned food, seafood and foil-wrapped baked potatoes) resulting in vegetative cells. A byproduct of the cells’ multiplication is the toxin.

Home-fermented tofu, a dish created by holding commercially-produced tofu room temperature for a couple of weeks, transferring to a glass jar with water, oil and spices and then sometimes holding at room temperature has a history of botulism.

In 2006 a California couple became ill with botulism intoxication after eating home-fermented tofu. According to CDC’s Morbidity and Mortality Weekly Report:

The tofu was a commercially packaged product purchased at a retail market. In the home, the tofu was boiled, towel dried, and cut into cubes. The cubes were placed in a bowl, covered with plastic wrap, and stored at room temperature for 10–15 days. The tofu was then transferred to glass jars with chili powder, salt, white cooking wine, vegetable oil, and chicken bouillon to marinate at room temperature for 2–3 more days. Finally, the fermented tofu was stored and eaten at room temperature.

The wife reported she has lived in the United States for more than 25 years and, during this time, has prepared fermented tofu using the same recipe she learned as a student in Taiwan. Preparation of this batch was not notably different, and the reason for contamination this time is not clear.

Two cases of botulism in New York were recently reported in CDC’s MMWR. A 39-year-old man and a 36-year-old woman who also consumed home-fermented tofu. Although the individuals did not know each other, the commercial tofu used to make the fermented product was purchased from the same retailer.

Patient 1’s wife and patient 2 had emigrated from the same locality in Jiangxi Province, China, to the United States within the previous 2 years. Both resided in Queens, but they did not know each other. They reported purchasing fresh bulk tofu in January 2012 at the same Chinese grocery in Queens. Patient 1’s wife cubed the tofu and placed it in a plastic container in layers separated by heavy paper. She covered the container with a nonairtight lid and allowed the contents to ferment at room temperature for 1 week. She next added chili pepper and salt, transferred the tofu to a glass jar, and stored it in the refrigerator for 3 weeks before consumption. Patient 2 placed blocks of tofu in a colander covered with plastic wrap and kept it at room temperature for 7–10 days. She then added salt, dried chili pepper, and orange peel, and stored the fermented tofu in glass jars in the refrigerator. The fermented tofu was not heated before consumption in either case.