On September 11, 2010, the headline of the day in Canada read, “Exploding Sauerkraut Brings in Hazmat Team.” Turns out a can of preserved cabbage exploded in a foods sciences class, exposing twenty-four students and four staff members at Kelly Road Secondary School to botulism.
Botulism is a rare but serious paralytic illness caused by a nerve toxin produced by the bacterium Clostridium botulinum and similar strains. Foodborne botulism is possible when eating foods contaminated by this bacterium, and may be linked to improperly canned or preserved food.
The students and staff members at the school were quarantined. Everything turned out okay. But if you’re into making your own fermented foods, there is a risk—though very small—of foodborne illness. What can you do to prevent it?
General Risks of Fermented Foods
The benefits of fermented foods far outweigh the risks. They provide a number of nutrients, including probiotics, which are connected to improved digestive health and immunity.
The main concern when making fermented foods is the very rare but possible threat of contamination with botulism-causing bacteria. In 2001, a botulism outbreak caused 13 people to be hospitalized in an Alaskan village, after they ate fermented beaver tail and paw. In 2006, others suffered botulism poisoning in Orange County caused by homemade tofu.
Other risks include the development of mold, or contamination by other types of bacteria. The good news is that with proper preparation, you can make sure that your homemade fermented food is not “toxin friendly,” and won’t encourage the presence of potentially damaging organisms.
Tips to Keep Your Fermentation Process Toxin-Free
To make sure your sauerkraut or kombucha tea or homemade kefir is safe to eat, take these precautions:
- Clean it: Make sure everything you’re using in the process, including your hands, tools, jars, etc., is sparkling clean.
- Weigh it down: Keep your cabbage or other food down under the brine. If it floats to the top, it’s exposed to air, where it can pick up nasty bugs.
- Brine it up: If you have too low a water/brine level, it gives undesirable bacteria and yeasts the food they need to grow on the surface. You can scrape off this “scum,” but you’ll be less likely to see it if you have a sufficient level of brine. Rule of thumb: one inch of brine above the sauerkraut.
- Lighten the load: If you pack your jar too full, you may not leave enough space for the fermenting reaction to take place without causing an overflow. A good rule of thumb—pack your jars only 75 percent full. Less than that can leave in too much oxygen. More can push out your brine.
- Salt it: Keep your salt ratio to three tablespoons to each quart of water. Salt makes the mixture less friendly to bugs.
- Seal it: If your jar doesn’t keep out the oxygen, your yeast in the ferment could be oxidized, forming vinegar. It will also increase risk of mold. This may be the most important step in making fermented foods—make sure the environment is oxygen-free. If you notice browned cabbage, a yeasty odor, slime, or mold, could be your jars aren’t airtight. Jars with airlocks are recommended, as they keep out oxygen, but allow for off-gassing.
- Measure it: Temperature is important in the making of fermented foods. The gut friendly bacteria thrive at certain temps, but will die off if the mixture gets too hot. Check your recipe and adhere to suggested temperatures using your thermometer.
- Keep it acidic: Foods with a low acid level are more hospitable to bacteria and spoilage. Your sauerkraut, for instance, should have a pH of 4.6 or lower. Use pH strips to test.
- Check it: If you see mold, your best bet is to start again. Some will say you can scrape it off, but you’re taking a risk as you’re leaving the spores behind. If you see the cabbage darken or turn pink, you could have a yeast issue or mold. (Likely an oxygen problem.) It could also mean you have an uneven distribution of salt. If you see a creamy film on top that smells yeasty, throw it out.
Do you have tips for making sauerkraut and other fermented foods safely? Please share with our readers.
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Bethany Lindsay, “Exploding sauerkraut brings in Hazmat team,” CTV British Columbia News, September 11, 2010, http://bc.ctvnews.ca/exploding-sauerkraut-brings-in-hazmat-team-1.551396.