The Potential Dangers of Flour

Cooking is always required before consumption, even with wheat-based products.

August 13, 2019

ALEXANDRIA, Va.—Remember the days when mom made cookies and let family members enjoy the dough from the near-empty mixing bowl? That treat is a big no-no, according to a report from Food Safety News.

The FDA warns the public against consuming uncooked flour because it can be contaminated “with a variety of disease-causing germs, including E. coli, salmonella and listeria. Eating uncooked dough or batter, whether for bread, cookies, pie crust, pizza and tortillas, can cause illness.” But traditionally many home bakers—and possibly even some foodservice employees—have ignored that advice.

Occasional recalls of flour confirm the value of that warning. In 2009, raw, prepackaged cookie dough was linked to food-borne illnesses in 77 people and triggered an E. coli-related recall. After nibbling on raw cookie dough, 35 of those 77 people had to be hospitalized, and 10 developed kidney failure. At first, the likely culprit seemed to be eggs, but an investigation subsequently pointed to the cookies’ flour. The dough manufacturer later switched to heat-treated flour.

In 2015, General Mills recalled 45 million tons of flour, and other companies issued secondary recalls on products ranging from bread and pancake mixes to meat and poultry products. Just last month, flour contaminated with E. coli O26 sickened 21 people in nine states. About 15% were hospitalized. Epidemiologic and laboratory evidence indicates that flour was the likely cause of the problem.

While it may seem unlikely that a staff of life could be so dangerous, flour is made from wheat, and wheat fields attract a variety of insects, wildlife and stray livestock.

According to the FDA, “if an animal heeds the call of nature in the field, bacteria from the animal waste could contaminate the grain, which is then harvested and milled into flour.” And there’s the problem. Animals can carry E. coli, salmonella, listeria and other pathogens that can contaminate human foods via a variety of routes.

After wheat is harvested, the kernels are taken to a mill where they are cleaned, milled and sifted to remove the outer layer of the kernel. The interior endosperm is then ground into flour. Cleaning the wheat comes down to removing unwanted objects such as stones, pieces of metal and wheat kernels with color differences. While milling doesn’t address microbial pathogens, contamination rates are extremely low.

Another thing to remember is that flour is a raw, uncooked product even though it looks “pure” in the processed form. Raw flour rarely makes people sick for one simple reason: It’s almost never eaten raw. Instead, it’s mixed with other ingredients to make bread, pie crusts, cookies and cakes. It can be boiled, as in the case of dumplings or noodles, or fried as in the case of fish breading. By thoroughly cooking raw flour, any pathogens that might be in it will not survive.

When it comes to refrigerated cookie dough, ready-made pie crusts and heat-and-bake rolls though, it’s a different story. If people nibble on those foods before cooking them, they put themselves at risk of getting sick from pathogens that might be in the flour.

In the end, it’s consumers who can do the best job of protecting themselves from foodborne pathogens that might be in flour and flour products. The solution is simple: Make sure to cook anything that contains flour.