Death by fermented foods | Scientific American

Death from fermented foods

By Michaela Maya-Mrschtik

I only developed an enthusiasm for fermented foods a few years ago. I didn’t even like yogurt before, but now I eat it almost every day and I’m always happy to eat kimchi, miso and sauerkraut. Many nutrition guides claim that I am doing something good for my body.

In most cases this may well be true. But in some fermenting foods, bacteria grows and produces an extremely powerful toxin called bongkrekic acid. Unnoticed, it builds up in food and gives anyone who eats it a dangerous case of food poisoning, as an October 2020 outbreak in a city in eastern China showed.

Twelve people had breakfast together at home. Nine of them died in the following two weeks. They all had one thing in common: they had eaten sour soup. The dish contained noodles that the hosts had made from fermented corn (kept too long and too carelessly). It only took a few hours for the victims of the poisoning to develop the first symptoms. At first, they noticed abdominal pain, felt nauseous and vomited. Some developed diarrhea and all quickly became very ill. The symptoms became so severe that they sought medical attention that same day. But the doctors could not help them. The first patient died just 20 hours after symptoms of poisoning began. Six more followed in the next 48 hours. The last two lasted a few days longer, but they also did not recover from the illness, and in this case everyone who had ingested the toxin died.

Overall, about half of these bongkrekic acid encounters end in death. Even the smallest amounts of this substance – one to one and a half milligrams – can cost the life of an adult. In the tragedy described, Chinese authorities discovered a concentration of 330 milligrams per kilogram in the homemade noodles that the victims had eaten. Assuming consumption of approximately 100 grams per person, this is approximately 20 to 30 times the lethal dose of the poison.

The preparation of the dishes made no difference. Unlike the bacteria that produce bongkrekic acid, the substance itself does not break down during cooking. And neither the taste nor the smell of the dish indicates its presence.

While a corn-based preparation was the problem here, bongkrekic acid was originally associated primarily with another food. The toxin even has its name: Tempeh Bongkrek. Tempeh is made from fermented soybeans. After soaking and cooking the beans, mold spores are added and the mixture is left to ferment for about two days in an airtight container. The resulting mass of plants and mushrooms can then be seasoned and fried or fried.

In addition to soy, tempeh bongkrek also contains coconut pulp as an additional ingredient. And the Gladioli Burkholderia the bacteria, which can produce bongkrekic acid, prefer to grow in this pulp. More precisely, it is a particular strain of this bacteria which produces a particularly large quantity of toxin, Burkholderia gladioli pathovar cocovenenansOr B. cocovenenans to make it short. Because consumption of tempeh bongkrek in Indonesia led to thousands of cases of poisoning, the country’s government felt compelled to ban its production in 1988. But just as the Germans wouldn’t allow their sauerkraut to be taken away, the same can be said for tempeh bongkrek. Even today, it is produced for private use or for the black market.

B. cocovenenans likes to grow on moist, starchy grains if they begin to ferment, either deliberately or due to improper storage. In addition to fermented corn preparations, these foods can include sweet potato flour and rice noodles, which have been blamed for some outbreaks in China.

While cases remain concentrated in Southeast Asia, in 2018 the disease also appeared for the first time in Africa. Between January 9 and 12, 234 people in Mozambique fell ill after consuming Pombe, a traditional drink made from corn flour. A total of 75 people died as a result of the poisoning.

And in 2024, there was a case in North America. The victim had prepared a dish of fermented corn flour. When he went to the hospital two days later, he complained of nausea, vomiting and exhaustion. At this point, his liver and kidneys were already severely damaged and his blood was acidic. His condition gradually deteriorated over the next few days and he died in hospital eight days later. So far, no cases of bongkrekic acid poisoning have been observed in Europe, but it cannot be ruled out that B. cocovenenans will appear there at some point.

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This article was originally published in spectrum of science and has been reproduced with permission.

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