How to avoid toxins when making homemade fermented bean curd

I heard in the news before that someone was poisoned after using homemade fermented bean curd. This is actually a very novel thing, because no matter what, the ingredients of homemade fermented bean curd are definitely of better quality, so how could it be poisonous? In fact, this is not a poison from food, but a "natural poison" produced during the production process of tofu due to fermentation and other reasons. It is this natural poison that causes the poisoning. Next, I will introduce this "natural poison" in detail.

The culprit that causes poisoning is called "botulinum toxin". This toxin is secreted by Clostridium botulinum and is much more toxic than arsenic and potassium cyanide.

Clostridium botulinum occurs naturally in nature and produces spores that are able to withstand heat. The spores are very hardy and normal heating and boiling are not enough to kill them. In the absence of oxygen and at room temperature, the spores grow into bacteria and are able to produce toxins. Generally speaking, symptoms of poisoning appear between 12 and 36 hours, but may appear in as little as four hours or as long as eight days.

After botulinum toxin poisoning, symptoms such as blurred vision, seeing double, drooping eyelids, difficulty swallowing, slurred speech, and muscle weakness may appear. If the disease is not diagnosed and treated promptly, it may lead to death. Even if the disease is diagnosed and treated, antitoxin injections and intensive care are required, so the cost is very high.

How to prevent botulism poisoning?

The consequences of botulinum toxin poisoning are serious, but fortunately it is not difficult to prevent. For Clostridium botulinum spores to produce toxins, two conditions are required:

1. Isolate from oxygen.

2. Normal temperature (generally between 15 and 57°C).

To prevent botulism poisoning, there are the following methods:

1. If food is stored in the refrigerator in time, even if there are botulinum toxin spores, botulinum toxin will not be produced.

2. If the food is stored at room temperature and has a high acidity (pH below 4.6), botulinum spores cannot survive. Therefore, if the pH value of food is lower than 4.6 and it is boiled and then sealed and stored, botulinum toxin will not be produced.

3. For neutral or low-acidic foods, even boiling cannot completely kill the spores. If such food is to be stored at room temperature, it needs to be sealed and heated in a pressure cooker to above 120°C for 20 to 30 minutes.

Finally, let me summarize and emphasize:

Botulinum contamination and botulinum toxin production are just one of the "natural toxins" that may occur in food. Different pathogenic bacteria and toxins have different growth characteristics and toxin properties. To prevent these "natural toxins", it is necessary to follow hygienic operations under scientific guidance in the preparation and preservation of food, and do not assume that "homemade food is safe." Especially for foods that involve fermentation and pickling, contamination is very likely to occur. If you lack scientific guidance or are not familiar with the production techniques formed by long-term experience, do not try it for granted.