What kills botulism on surfaces?
Botulism: What You Don’t See or Smell Can Still Hurt You
Botulism is the name of the food poisoning we get by consuming the toxin of bacteria Clostridium botulinium. Botulism is a rare but serious foodborne disease that can be fatal. There are two different types of botulism poisoning associated with foods—adult and infant botulism.
Where Does Botulism Come From?
The bacteria, Clostridium botulinum, grow anaerobically, meaning they grow in the absence of air—in places like home-canned products and in the intestines of animals and humans. The bacteria produce spores that are very resistant to heat and chemicals, and under the right environmental conditions, can transform into an active bacteria. The spores can be found in soil all over the world and can contaminate vegetables in the field and other natural foods such as syrup and honey. The toxin that Clostridium botulinum produces is among the most deadly food toxin known. Fortunately, heat destroys the toxin and cooking is the best way to control botulism.
Symptoms of Illness
The symptoms of botulism depend upon the age of the person exposed. In adults this may include difficulty in swallowing, speech, and breathing, and double vision. The onset of botulism is usually 18 to 36 hours after eating the contaminated food, although it can be as soon as four hours and as long as eight days. In infants, signs of botulism include constipation, muscle weakness, and loss of head control, also called «the floppy baby.»
Public Health Consequences
The exact number of botulism cases that occur each year is hard to determine because the local Health Department and Centers for Disease Control and Prevention (CDC) cannot record the number of cases accurately unless the ill person seeks medical care, which is unusual in mild cases. The CDC has calculated an estimate of the number of cases of botulism based on corrections for underreporting or misdiagnosis. The CDC estimates that there are 55 cases of botulism each year in this country, and that 100% of the cases are caused by eating food contaminated with the toxin produced by the bacteria. About 42 cases will be severe enough to require hospitalization; 9 deaths are possible each year.
Anyone can become ill by eating food that has been improperly stored. Some will have more severe symptoms depending on the dose of toxin that they consume. Infants are particularly at risk.
How Can Botulism Be Prevented?
There are very few cases of botulism each year. The death rate is high if not treated immediately. Prevention is extremely important. Botulism spores can produce the toxin if mistakes are made in home canning food. Home canning should follow strict instructions and hygienic recommendations to reduce risks. Pressure canners should be used for all foods that are naturally low in acid. The botulism spores can only be killed by the high heat that can be obtained in a pressure canner. In addition, home-canned foods should be boiled for 20 minutes before tasting or eating.
Are Home-canned Foods the Only Concern?
Infant botulism is a concern for children under one year of age. It is possible for bees to pick up the botulism spores from flowers or soil. These spores are not destroyed during the processing for honey. The botulism spores grow in the baby’s intestinal tract and then produce the toxin. This is less likely to occur after the age of one year when the baby’s digestive tract matures.
Flavored oils also can be a concern if not prepared correctly. When herbs, garlic, or tomatoes are placed in oils, the botulism spores on the plant material can start to produce the toxin in this anaerobic mixture. To be safe, keep these flavored oils refrigerated and make only the amount of herbal oils and butters that will be used in a few days. Using dried herbs and vegetables will also reduce the risk.
Baked potatoes wrapped in foil and kept at room temperature occasionally form the anaerobic conditions the botulism spores need to produce their toxin. For this reason, leftover potatoes should be refrigerated. Potato salad made from leftover baked potatoes that have been improperly refrigerated has been implicated in botulism poisoning.
How Can I Control the Pathogen in My Home?
- Boil all home-canned, low-acid foods 20 minutes before eating. Low-acid foods are most vegetables, some tomatoes, and meat or poultry.
- Discard all raw or canned food that shows any sign of being spoiled.
- Discard all bulging or swollen cans of food and food from glass jars with bulging lids.
- DO NOT TASTE food from swollen containers or food that is foamy or has a bad odor.
- Process low-acid foods at temperatures above boiling (which can only occur using a pressure canner) and for the recommended time for the size of can or jar you are using.
- Can low-acid foods in a pressure canner. Do not can low-acid foods in the oven, in a water-bath canner, open kettle, or vegetable cooker.
- If you suspect that home-canned food has spoiled, heat the food to boiling to destroy possible toxin, then discard the food. Do not eat this food. Clean all surfaces with chlorine/water solution (one tablespoon of bleach per gallon of water) that leaky containers may have contaminated. Then boil any sponges or cloths used for clean-up to destroy the toxin. Then, discard the sponges or clean-up cloths.
- Do not give honey or foods with honey to infants under one year of age.
There are a number of organisms that can make people sick. It is not possible to determine which pathogen is causing the problem based on symptoms alone. Individuals suffering from serious illness should seek appropriate medical advice.
Centers for Disease Control and Prevention. (2022). Botulism. U.S. Department of Health & Human Services.
Scallan, E., Hoekstra, R.M., Angulo, F.J., Tauxe, R.V., Widdowson, M.A., Roy, S.L., Jones, J.L., & Griffin, P.M. (2011). Foodborne illness acquired in the United States—major pathogens. Emerging Infectious Diseases, 17(1), 7–15.
For more information about food safety, visit Foodsafety.osu.edu.
Revised by Lydia Medeiros and Jeffery LeJeune.
Botulism: take care when canning low-acid foods
Canning vegetables from your garden can be fun to do. What could be more delicious than a wintertime meal prepared with the vegetables you preserved during the summer?
Use a pressure canner for low-acid foods
Canning low-acid foods requires special care. This includes red meats, fish, poultry and all vegetables (except for most tomatoes). Low-acid foods can support the production of the deadly botulism toxin if these foods are not processed properly in a pressure canner. A pressure canner heats food to high temperatures (240-250 degrees F or higher) and destroys the spores that produce the botulism toxin. A boiling water bath canner, which can be used for canning pickles or fruit, heats food to boiling temperature (212 F), which is not high enough to ensure safety for canning vegetables and other low-acid foods.
Botulism is the most deadly food poisoning known
Clostridium botulinum bacteria are the main reason why low-acid foods must be pressure-canned to be safe. Clostridium botulinum is a common soil microorganism that produces a very deadly toxin or poison. This food poisoning, called botulism, is the most deadly food poisoning known. Home-canned foods are responsible for over 90% of all cases of foodborne botulism. Therefore, all vegetables to be canned must be washed thoroughly and peeled, trimmed or chopped as directed.
Clostridium botulinum spores can be destroyed by pressure canning food at a temperature of 240 F or above for a specific period of time.
Low-acid, canned food provides the perfect condition for botulinum spores to multiply
Botulinum spores are on most fresh food surfaces, but because they grow only in the absence of air, they are harmless on fresh foods. The conditions which favor the germination of these spores are low acidity (such as in vegetables and meats) and the absence of air (such as in a sealed canning jar). These Clostridium botulinum spores can be destroyed by pressure canning the food at a temperature of 240 F or above for a specific period. If you find timetables on recipes for processing low-acid foods in a boiling water bath canner, do not use them. Research has shown that these timetables present a very real risk of botulism.
- Pickling or canning salt can be added for flavor but does not prevent spoilage.
- Spices and herbs may be added in small amounts.
- Never add butter, fat, flour, rice, barley or pasta unless the tested recipe directs you to do so.
- Adding ingredients that are not called for in the recipe may result in an unsafe product.
Follow these pressure-canning steps to kill botulinum spores
Successful processing in a pressure canner requires attention to several details:
- Vent pressure canners for 10 minutes at the start of processing. Venting drives air from the canner. If air remains trapped in the canner, the canner will not reach pressure or pressurization will take a long time. A poor, unsafe product will be the result.
- Adjust for elevation. When pressure canning meats and vegetables, it is important to adjust processing pressure for elevation. The highest altitude in Minnesota is 2,000 feet.
- Dial gauge, up to 2,000 ft. — 11 pounds pressure (11 psi).
- Weighted gauge, up to 1,000 ft. — 10 pounds pressure (10 psi).
- Weighted gauge, above 1,000 ft. — 15 pounds pressure (15 psi).