Even more evidence this week from the Centers for Disease Control (CDC) of the importance of cooking flour-containing products before eating. National foodborne illness outbreaks in 2016 and again in 2019 tied to pathogenic E. coli have been linked to consumers eating raw dough or batter. An outbreak report released this week indicated that several people interviewed admitted to eating, licking or tasting raw dough or batter before they became sick. The infectious bacterium was found in bags of all-purpose flour purchased by consumers.
The symptoms of E. coli infections vary but often include severe stomach cramps, diarrhea (often bloody), and vomiting. People usually get sick 3 to 4 days after swallowing the germ. Most people recover within a week. However, some people develop a serious type of illness called hemolytic uremic syndrome (HUS), which can result in kidney failure, stroke, and even death. In the 2019 outbreak tied to contaminated flour, 21 cases were reported with three hospitalizations. The complete outbreak report is available.
What can we learn from this? Consumers and educators should remember two quick and easy messages: Bake before you bite! or Say NO to raw dough. When you prepare homemade dough for cookies, cakes, and bread, you may be tempted to taste a bite before it is fully baked. But steer clear of this temptation—you can get sick after eating or tasting unbaked products that are intended to be baked, such as dough or batter. And remember, children can get sick from handling or eating raw dough used for crafts or play clay, too.
Flour can be contaminated, just like other agricultural products. Flour doesn’t look like a raw food, but as purchased in the grocery store, it is! Flour is ground and sifted as part of the milling process, but these steps don’t supply enough heat to destroy harmful bacteria that may be on the grains as they are harvested. In addition to harmful bacteria contaminating the flour while it’s still in the field, it’s possible to spread contamination at other steps during flour production.
Fortunately for anyone looking forward to celebrating graduation, birthdays or other events, the bacteria that can contaminate flour are destroyed by cooking or baking. Cooking or baking also destroys Salmonella that may be present in raw eggs.
The CDC recommends safe food handling practices when you are baking and cooking with flour and other raw ingredients:
- Do not taste or eat any raw dough or batter, whether for cookies, tortillas, pizza, biscuits, pancakes, or crafts, made with raw flour, such as homemade play dough or holiday ornaments.
- Do not let children play with or eat raw dough, including dough for crafts.
- Bake or cook raw dough and batter, such as cookie dough and cake mix, before eating.
- Follow the recipe or package directions for cooking or baking at the proper temperature and for the specified time.
- Do not make milkshakes with products that contain raw flour, such as cake mix.
- Do not use raw homemade cookie dough in ice cream.
- Cookie dough ice cream sold in stores contains dough that has been treated to kill harmful bacteria.
- Keep raw foods such as flour or eggs separate from ready-to-eat foods. Because flour is a powder, it can spread easily.
- Follow label directions to refrigerate products containing raw dough or eggs until they are cooked.
- Clean up thoroughly after handling flour, eggs, or raw dough:
- Wash your hands with running water and soap after handling flour, raw eggs, or any surfaces they have touched.
- Wash bowls, utensils, countertops, and other surfaces with warm, soapy water.
The CDC has prepared these safe handling recommendations in Spanish as well.