(This article, focused on consumers, is by Julia Darnton and Phillip Tocco of Michigan State University Extension. It was originally posted here on Dec. 16, 2014, and is reposted with permission. Part 2, focused on growers, will appear tomorrow.) In 2011, an outbreak of Salmonella Enteritidis was linked to alfalfa sprouts and spicy sprouts in the United States. This was right after an outbreak of European E. coli O104 in Germany, which sickened thousands and was linked to 50 deaths. Recalls of sprouts as a result of Listeria created yet more concern in the U.S. Each of these outbreaks was linked to a different harmful bacteria feared in foodborne illnesses. Since that time, many restaurants have taken sprouts off the menu, including the sandwich chain Jimmy John’s. Sprouts still appear at some farmers markets and are desired for adding flavor to salads, juices or entrées, both by professional chefs and home cooks. What causes sprouts to be dangerous? How can sprouts be safely consumed? Bacteria that cause foodborne illness can lurk anywhere there is a host for them to thrive. In sprouts, the seed can, and does, carry the foodborne illness pathogen. This is why we have to take advisories such as “Refrigerate after opening” very seriously and do our best to minimize the sources of foodborne illness in our own homes. Michigan State University Extension has a team of educators dedicated to helping consumers understand the risk and hazards of foodborne illness. The common hosts for foodborne illness are categorized as “potentially hazardous foods” or PHFs. Raw sprouts are listed among other foods that are categorized as PHFs such as meats, dairy products, cut melons, cut tomatoes and cut leafy greens. PHFs must be kept colder than 41 degrees F or must be kept above 135 F (please note this is holding time, not cooking temperature, which varies based on the food type). The University of California at Davis advises that, “The best conditions for sprouting are also ideal for multiplication of pathogenic bacteria if they happen to be present on the seed.” So seeds are sprouting in the ideal conditions for bacteria to grow and sprouts are a documented host for many different bacteria that cause foodborne illness. This is why raw sprouts are potentially hazardous foods. The designation of PHF does not mean that people shouldn’t eat these foods or shouldn’t purchase these foods. Much like ordering a steak or an egg in any other way but fully cooked, eating raw sprouts means you run the risk of contracting a foodborne illness when you eat it. In healthy individuals, these foodborne illnesses are nothing more than a day or two of nausea or diarrhea. For those who would be considered highly susceptible or vulnerable to foodborne illness, including young children, the elderly, pregnant women and those with compromised immune systems, it could mean long-term health issues such as severe rheumatoid arthritis, miscarriage, kidney failure or death. Instead, the designation of PHF means that these foods need to be carefully prepared and stored at the proper temperature, and, if not handled correctly, discarded without being consumed. The Michigan Department of Agriculture and Rural Development (MDARD) enforces the Michigan Food Code, which lists raw sprouts as a potentially hazardous food and requires time and temperature control for food safety. This means the storage and holding of this product must be closely monitored. The time/temperature control for safety for raw sprouts is 41 F (5 degrees Celsius).

  • Keith Warriner

    Holding sprouts at refrigerated temperatures will stop them spoiling quickly but wont do much in terms of food safety. The microflora of sprouts is defined within the fist 48 h into the sprouting period were most of the pathogen growth would occur. Pathogens introduced after this time will persist but not grow due to the biological background buffer.

  • Dommy

    The other day while shopping I considered buying organic broccoli sprouts, but passed because of these concerns. Wondering if store bought sprouts can be rinsed in hot water at home to kill off any pathogens?

    • Loy

      No. Generally a pure water bath/wash will result in a one log reduction of bacteria on the surface of what you’re washing (90% reduction), and you won’t be using temperatures hot enough to destroy all of the bacteria cells without actually cooking the sprouts. A 90% reduction can seem significant to the layperson, but depending on the infectivity of the pathogen in question, it usually is not enough to make the product safe. You should also consider that if bacteria has penetrated into cracks, crevices, or even porous tissue, it will not be washed out using conventional means.

  • Lars Krusell

    Good thinking! You certainly will reduce batcerial level by acid treatment after the sprouting as well as a short heat treatment (scalding with water) will do. But if it will render the sprouts safe is an interesting academic question. In practice there has not been recognised significant outbreaks with home sprouting, when seeds are first rinsed well and sprouts are rinsed at least daily with clean drinking water and sprouts are kept only a few days in the fridge. But I would advise scalding or acid treatment (soak with vinegar) of the seeds before sprouting and the same with the sprouts. Check my comment on article #2.