by Cristina Marrone
Minimal quantities of foods with botulinum toxin can be enough to cause the disease botulism, which can be fatal. Tips for preparing preserves safely
A 46 year old woman Gerardina Corsano from Ariano Irpinio died due to suspected food poisoning caused by botulinum, perhaps present in a chili condiment used in the restaurant. Even the consumption of minimal quantities of food contaminated with botulinum toxins can be enough to cause the disease botulism, i.e. the blockage of the transmission of the nervous signal to the muscle, a condition that can be fatal.
What is botulinum toxin
Botulism toxin develops from the microorganism Clostridium botulinum, common in soil and air and harmless as long as it comes into contact with oxygen. Sometimes it is poor food storage conditions that turn it into a health threat. There neurotoxin
it is in fact produced in the absence of oxygen and when temperatures exceed five to ten degrees. However, it does not form in very acidic environments, such as tomato sauce or vinegar. Its real enemy is heat, which destroys it: just cook food at 105 degrees for two hours or in a pressure cooker for ten minutes. However, if cooking is done briefly and foods are stored in oil there is the risk that some spores may escape.
Generally the level of environmental contamination in botulinum spores is very low and can be punctiform, therefore in the same production batch it may occur that only some packages are contaminated.
Symptoms
The symptoms of intoxication generally appear within 12-24 hours and, usually, the earlier they are, the more serious the disease. They can vary from a mild malaise that does not require medical intervention, up to a fulminant illness that leads to death in a few days. The first symptoms are characterized by weakness, dizziness, dryness of the throat, followed by signs of paralysis, especially affecting the muscles innervated by the cranial nerves: difficulty swallowing and speaking, visual disturbances (strabismus, double vision, drooping of the eyelids). ) in severe cases death occurs due to paralysis of the respiratory muscles. For botulinum poisoning, an antitoxin taken in the first hours after the onset of symptoms is used. If the patient survives, recovery is rapid and complete.
How botulinum poisoning occurs Clostridium botulinum is a bacterium capable of producing a neurotoxin that interferes at the level of nerve endings, causing the blockage of some vital functions such as respiratory function. Poisoning with this bacterium generally occurs following the consumption of canned food (canned and low-acid preserves, in oil or vacuum-packed and not adequately sterilised). The presence of botulinum in food should be suspected in the presence of swelling of the lid, the release of gas when opened and its unpleasant odor.
How to avoid botulism in preserves
A set of food safety rules they can be useful to those who prepare home preserves: from jams to pickles, from sauces to products in oil.
– Mushrooms, olives, peppers, aubergines and green beans in oil are the foods at greatest risk and must be washed well to avoid residual soil in clean, dry and airtight jars.
– Acidification above 4.6 pH makes the environment unsuitable for the growth of botulinum, which is why when preparing vinegar preserves, the vinegar must completely cover the preserved product, without skimping.
– it is necessary to wash vegetables, dishes, worktops and containers to limit or eliminate the presence of the bacteria and spores. For this purpose, the production phases should be separated (for example, do not reuse containers used for vegetables to be cleaned and then put the washed vegetables back in).
– Containers should not be filled to the brim but an empty space should be left between the maximum liquid level and the neck of the container to be able to generate a vacuum inside the container.
– Botulinum toxin is destroyed at high temperatures and therefore the sterilization of jarred and canned foods by boiling for at least 10 minutes guarantees its elimination. During heat treatment the jars must be completely immersed in boiling water. This is not a real sterilization (it would be necessary to reach 121 for 3-4 minutes to also eliminate the spores) but in this way the
to most microorganisms
– Botulinum toxins are all thermolabile and are therefore rapidly destroyed by common food cooking temperatures (at least 80C for 5 minutes). For this reason it is advisable to boil homemade preserves before using them (for example, in the preparation of a sauce, heating it adequately).
– Once the jar has been opened, the product should be stored in the refrigerator for a short time.
-Throw away preserved products about which you have doubts about the state of conservation, which have undergone breakages in the cold chain, or whose perfect preservation you are not sure of (for example the presence of air in vacuum packs, hermetic capsules which emit the characteristic ” click” following pressure on the cap or, on the contrary, “swollen” capsules due to bacterial fermentation). The product inside must not have an unnatural color or odor, nor bubbles rising upwards from the bottom.
November 1, 2023 (changed November 1, 2023 | 5:30 pm)
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