How to Destroy Botulism Toxin in Low Acid Foods
Botulism is a serious food-borne illness characterized by paralysis and death if untreated. It is caused by a toxin created by the clostridium botulinum bacteria. Four cases of botulism linked to refrigerated carrot juice, a low-acid food, occurred in the United States in 2006. Botulism is also associated with home-canned low-acid foods, such as vegetables, sauce, soup or meats. The heat of boiling or pasteurization is effective at killing clostridium botulinum and destroying the toxin, but not all types of spores. Refrigeration keeps remaining spores dormant, preventing them from developing into bacteria and producing the dangerous toxin that causes botulism.
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Instructions
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Process food at high temperature. Botulinum needs an environment with a temperature range between 40 and 120 degrees F to produce its toxin. Low-acid food that is being prepared for packaging or canning should be processed to a heat well in excess of 120 degrees, ideally between 240 and 250 degrees for 30 minutes. Such treatment kills the bacteria, destroys toxin and kills the spores of all but the most heat-resistant strains (proteolytic).
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Keep stored food refrigerated. After being subjected to high temperatures, the packaged or canned food should be refrigerated at temperatures below 50 degrees, and ideally below 40 degrees.
Though properly sealed containers should not need to be refrigerated, keeping them below 40 degrees ensures that botulinum toxin will not be produced even if the bacteria is present. Refrigeration keeps any remaining proteolytic spores dormant and prevents them from developing into bacteria and producing toxin.
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Boil infected food and containers for 30 minutes. Low-acid food that has been stored and appears to have been infected with botulinum should be boiled fully submerged for at least 15 and up to 30 minutes, which is enough to destroy any botulinum toxin and kill the bacteria.
Under no circumstances, however, should such food be eaten or its storage containers reused. Discarding the food and containers without boiling creates a risk that the bacteria and its spores can pass to pets, other people or kitchen surfaces.
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Tips & Warnings
Title 21, Part 113 of the Code of Federal Regulations for thermally processed low-acid foods packaged in hermetically sealed containers. The amount of time required at 240 degrees to sterilize food in preparation depends on the kind of food, and varies from as little as 20 to as much as 100 minutes. In higher altitudes, a pressure cooker should be used to obtain the adequate heat.
Lowering the pH of the food below 4.6 (increasing the acidity) will prevent the further growth of botulinum but will not destroy existing toxin. Don't simply throw away food and containers that have been infected with botulinum. Because the toxin is so dangerous, responsible disposal includes boiling to kill the bacteria and destroy the toxin.
