We often speak to callers about the possibility of botulism poisoning if they don’t process their low acid vegetables properly. But really, what is botulism poisoning and is there really a risk?
Clostridium Botulinum bacteria live in the soil. The vegetables that we harvest and preserve were either grown in the soil or rain water may have splashed dirt up onto them. It is not uncommon for green beans to have dirt on them; this dirt could contain botulism bacteria.
This bacterium grows well in low acid foods (high pH) and the absence of oxygen. These are just the conditions you will find inside a jar of home canned beans (or other low acid vegetables). The heat of canning from a boiling water bath canner is not hot enough to destroy the bacteria if they are present. The “if” is a big part of this equation. We often speak to people who have processed their beans in a boiling water bath canner for years and “nobody has died yet”. However, if the bacterium is present you will not be able to see, smell, or taste it. Likely your first indication of the contamination in your jar will be symptoms of the poisoning. Botulism toxin is a neurotoxin that may first cause gastrointestinal symptoms (nausea, vomiting, diarrhea, or constipation). The neurological symptoms will appear in a very short time—blurred or double vision, difficulty in swallowing, breathing, speaking, dryness of the mouth, and paralysis of different involuntary muscles. Death usually results from respiratory failure. It takes only a very small amount of the toxin to sicken or kill you.
Since the consequences of ingesting the toxin are very high (possible death), even though the frequency is low, it is important to process vegetables according to the directions in tested recipes. Remember that all of the vegetables that you grow in your garden are low acid and must be processed in a pressure canner.