Pre-packaged cookie dough might taste lovely, but you should resist the temptation until it has been properly baked if you want to avoid getting an E. coli infection, researchers from the CDC (Centers for Disease Control and Prevention) reported in Clinical Infectious Diseases. The authors explain that the 2009 outbreak of STEC (Shiga toxin-producing E. coli) which affected several US states was caused by commercial prepackaged cookie dough.

Eating uncooked cookie dough is popular, especially among teenage girls. In fact, the researchers learnt that many customers buy them with no intention of baking or cooking – they simply eat it as it is..

77 patients from 30 states became ill during the 2009 outbreak; 35 of them had to be admitted to hospital.

The authors wrote that in order to better prevent future outbreaks, the message on cookie dough packages should be more visible and simple – “Don’t eat this dough before it is baked!”.

Karen Neil, MD, MSPH, and team, which also included experts from state health departments, came to two conclusions:

  • Cookie dough makers should reformulate their produce so that the risk of infection is minimized, even in its raw state
  • Consumer education regarding the health hazards of eating unbaked cooking dough should be more effective

Food-borne illnesses caused by E. coli in the USA have been linked to leafy green vegetables, melons, salami, unpasteurized apple cider, sprouts, and ground beef.

3.6 million cookie dough packages were recalled in 2009. After an investigation was ordered and carried out, no production process, vehicle or single source linked to the dough could be identified as a definite contributor to the contamination.

The team believes that one of the dough’s ingredients was tainted. Their investigation implicated four ingredients, but not conclusively. The authors explained that just one purchase of tainted flour might have been used in the making of several different lots and types of dough. By examining the contamination status of the products’ use-by dates, they were able to make an approximate estimate of when, during that production period, contaminated doughs were being manufactured.

Most cookie dough ingredients undergo a “kill step”, such as margarine, baking soda, sugar, molasses, and pasteurized eggs – flour ordinarily does not. Chocolate was ruled out as a possible contributor to the outbreak, because eating chocolate chip cookie dough is much less linked to illnesses of this kind, compared to other cookie dough flavors.

The authors wrote:

“Foods containing raw flour should be considered as possible vehicles of infection of future outbreaks of STEC.”

Dr. Neil and team say that makers of baking products should perhaps use pasteurized or heat-treated flour in ready-to-cook foods – especially those that can easily be consumed before they are baked.

They add that manufacturers should strive to make their pre-baked products as safe to eat as they are after baking.

The authors concluded in an Abstract in the journal:

“Manufacturers should consider formulating ready-to-bake commercial prepackaged cookie dough to be as safe as a ready-to-eat product. More effective consumer education about the risks of eating unbaked cookie dough is needed.”

They stressed that even educating consumers about the health risks may not be enough.

Written by Christian Nordqvist