Do you love the idea of canning veggies from your garden but refrain from doing so for fear of botulism? Does your home canning consist of only basic jams and jellies because you’re convinced that if you attempt to can green beans you’ll do it improperly and kill your family?
You’re not alone. Botulism strikes fear in the hearts of home canners everywhere. Botulism toxin is one of the deadliest neurotoxins in the world. Once it enters your body, it blocks nerve function, causing muscle paralysis and eventually death.
The name for botulism comes from botulus, the Latin word for sausage. Originally known as Kerner’s Disease, one of the earliest outbreaks was recorded in 1793 by the physician Justinus Kerner in the town of Wildbad, Germany. Many people fell sick and died after eating contaminated sausage.
Today, instances of foodborne botulism at home often come from home-canned goods that were processed improperly. But the good news is that botulism contamination in home canning is completely preventable. You can safely preserve and eat fruits, vegetables, meat, poultry, seafood, anything — as long as you take the necessary precautions.
So what is botulism, anyway? Clostridium botulinum is a soil-borne, single-celled bacterium that is intolerant of oxygen. When exposed to oxygen, it converts into an armored spore that can lay dormant for hundreds of years. But when a botulism spore finds itself in an anaerobic environment once again, it re-animates back into its bacterial form. In this form it grows, reproduces and produces botulism toxin, which is so lethal that even one microgram is enough to kill you.
Inert botulism spores are found everywhere: in oceans and lakes, in the silt at the bottom of streams, in horse and cattle manure, and in the soil in your backyard garden. It’s more common in the West than in the rest of the United States because the soil from the Rocky Mountains to the Pacific Ocean contains an especially high count of botulism spores.[i] This, combined with the added factor of high altitude in the Mountain West, makes botulism especially concerning for home canners there.
Because botulism is ever-present in the soil, it doesn’t matter how sanitary you are in your home canning; botulism can be found in almost all foods. But since the bacteria can’t grow in the presence of oxygen, it’s harmless in fresh foods. That’s why you’ll never get botulism from eating fresh tomatoes from your garden.
Canned foods are a different story. To re-animate and grow, botulism spores require warm temperatures, moisture, and an oxygen-free, low-acid, low-sugar environment. So when you seal fresh foods in canning jars and store them at room temperature in your cupboard, you’ve created the perfect environment to grow the world’s deadliest neurotoxin. Since the toxin is odorless and tasteless, you can open a jar from your pantry and eat toxic food without realizing it. Within 12 to 36 hours symptoms start setting in, and a few days after that you could be dead.
That, of course, is the worst-case scenario. The death rate from botulism once was 70 percent, but since the invention of artificial respirators, it has dropped to only 5 percent. But in a collapse or crisis situation, you can’t depend on respirators and hospitals to take care of your family. All things considered, it’s better to avoid botulism poisoning by canning food correctly.
Water Bath Canner Versus Pressure Canner
The most important thing you can do to avoid botulism poisoning is to choose the correct canner to process your food. Water bath canners or steam canners, which are commonly used for jams and jellies, won’t do the trick, and here’s why: To kill clostridium botulinum spores, you have to get food to a temperature of 250° F (121° C) for at least three minutes. But water at sea level boils at only 212° F (100° C), so it’s impossible to achieve a high enough temperature in a water bath canner. If you live at a higher elevation, the atmospheric pressure is even less, so the boiling temperature is even lower. You can boil your veggies all day, but that will only kill active botulism bacteria, not the spores, leaving them to grow again and produce more toxin when conditions are right.
The only way to get the temperature high enough to kill botulism spores is to increase the pressure so that the boiling temperature is raised. And that’s where the pressure canner comes in. In a pressure canner, you add 10 to 15 pounds of pressure so that you can get your food up to the requisite 250° F to kill botulism spores. (Actually, home canners can only raise the temp to 240° F, or 115° C; to kill the spores at this lower temperature, the food must be exposed to that temperature for a longer period of time to destroy the spores.)