(This article by Martha Filipic, a writer/editor with the College of Food, Agricultural, and Environmental Sciences at The Ohio State University, was originally posted here on Aug. 17, 2015, and is reposted with permission.) COLUMBUS, OH—It was a church potluck like any other. But within days, botulism killed one Fairfield County woman and hospitalized 24 others. It was from potato salad, made with improperly home-canned potatoes. Foodborne botulism is rare, but the April 2015 incident was a somber reminder of the importance of strictly following home food preservation guidelines, said Shannon Carter, family and consumer sciences educator in Fairfield County for Ohio State University Extension. OSU Extension is the outreach arm of The Ohio State University’s College of Food, Agricultural, and Environmental Sciences.

Last year, Carter offered two home-food preservation classes to county residents. This year, she offered 10. And those were just a few of the classes offered by OSU Extension across the state. Listings are available at fcs.osu.edu/food-safety/home-food-preservation, along with links to how-to videos and other resources. “Foodborne botulism can be caused by using the wrong canning method,” Carter said. A pressure canner, rather than a simple boiling water bath, is necessary to kill botulism spores in low-acid canned foods such as meat, potatoes and other vegetables. “But people still water-bath their green beans and other foods,” Carter said. “And if they’ve done it that way successfully for years, why would they change?” Even if canning jars are properly sealed, botulism spores can grow. In fact, such spores can grow only in a sealed environment without oxygen, Carter said, along with high-moisture and low-acid conditions. “Water boils at 212 degrees,” she said. “If you have a boiling water canner, you can boil something for three, five, even 25 hours, and it will still only get to 212 degrees. To kill Clostridium botulinum spores in low-acid foods, you need to get the temperature up to 250 degrees, and the only way to do that is to use a pressure canner.”

Official home food preservation guidelines, available online at the National Center for Home Food Preservation, are periodically updated, Carter said. So, if you are following old guidelines, you aren’t getting the most accurate information. For example, tomatoes used to be considered a high-acid food, but today’s varieties are often right on the line between high-acid and low-acid, so citric acid or vinegar must be added to them before being canned. Also, standard household vinegar is now often at a lower strength than it used to be, Carter said, so following old recipes, possibly passed down for generations, that call for vinegar to acidify a food for water bath canning may not provide the margin of safety necessary.

Many people who have canned for years — even decades — are unaware of new recommendations, she said. And, surprisingly, she added, canning methods portrayed on televised food shows, websites, and even in some cookbooks are often improper. “People don’t know what they don’t know,” Carter said “So we’ve been trying to get information out to people. It’s important.” Deb Kilbarger, registered sanitarian and food program supervisor for the Fairfield Department of Health, said the April incident was the first time she and her colleagues, some of whom had worked in public health for decades, had seen a case of foodborne botulism, “let alone an outbreak.” The crisis made a lot of people sit up and take notice, said Kelly Spindler, registered sanitarian and director of environmental health for the department. “It helped people understand how serious food safety is, what can go wrong if food is not properly prepared or held at the proper temperatures, and, in canning, how important it is to follow certain procedures,” Spindler said. Aubry Shaw, of Grove City, attended two of Carter’s sessions this summer. She still misses her mother-in-law, Kim Shaw — the woman who died in the botulism outbreak. “She was always smiling,” Shaw said. “She was a wonderful mother. She was a great provider for the family. She would go out of her way to do anything for anybody. She was amazing.” The personal experience of losing someone to foodborne botulism drew Shaw — and her grandmother — to participate in Carter’s canning classes. “Even if you’ve had some experience in canning, there’s always something you can learn,” Shaw said. “That’s why it’s important to come to classes like this. I think food safety programs like this from the Extension office are incredible.” In fact, Kilbarger said, she knows of no other organization that offers home food preservation classes like Extension’s. “Anyone who cans should take the class,” Kilbarger said. “Even if you’ve been doing it forever, there might be a safer way. Hopefully, these classes will prevent anything like this from happening again.” Shaw provided an additional word of guidance: “If you home can, just be safe about it. If you have canned something and it doesn’t seem quite right, just throw it out. It’s not worth taking a chance.” (To sign up for a free subscription to Food Safety News, click here.)