Organic Italian olives are the unlikely suspects in a new botulism outbreak, which has sickened two people in Europe. The Food and Drug Administration has urged people not to eat Bio Gaudiano organic olives stuffed with almonds, and the United States distributor has recalled the product.
Scientists say that the case is a good reminder that just because a product is organic, that doesn't mean it's pristine. In some cases, organic products may be even more vulnerable to certain toxins than conventionally grown foods.
That's because organic food is often fertilized with manure, which can carry dangerous spores that occur naturally in soil. And if clostridium botulinim, the bacteria that causes botulism, makes it as far as a jar packed with oil and not much oxygen, it can flourish.
"It's the perfect environment for botulinum to grow," says Eric Johnson, a professor of microbiology at the University of Wisconsin-Madison.
The Salt tracked down Johnson in Rome, where by coincidence he'd just given a talk at the Italian research institute that was investigating the botulism outbreak. He said the case reminded him of an outbreak in the 1980s, which was caused by chopped garlic packed in oil. "Garlic is from the soil, so it has spores of botulinum in it," Johnson says. The oil floats on top of the jar and seals out air, leaving water to collect at the bottom, where it acts like a Petri dish for botulism.
Though most of the recent food safety scares have come from fresh foods like cantaloupe, sprouts and ground turkey, the olive outbreak as well as a French tapenade and dried tomato paste scare make it clear that pricey imported treats are not immune to processing slip ups. And organic foods are as vulnerable to botulism as other foods — if not more so because farmers so often use manure to grow them.
Food processors are generally diligent about fighting botulism. Salt is used to cure olives, but the food would have to be unpalatably salty to stop the bacteria. And Johnson, who has studied the deadly bacterium for three decades, says that some strains can survive boiling for hours.
After the outbreak in chopped garlic, the FDA told garlic processors add phosphoric acid. The higher acid level thwarts bacterial growth. Another strategy used by big commercial processors is a "bot cook", which involves cooking foods at high temperatures under pressure to wipe out spores.
About 145 cases of botulism are reported in the United States each year, but only about 15 percent of those are caused by food. Most of those are caused by home-canned food. Canning enthusiasts should fear not, however. There are plenty of easy ways to prevent foodborne illness when preserving fruits and vegetables. For more on how to can food safely, check out April Fulton's Q & A with a home-canning expert.