Critical germs not uncommon
2020 showed according to the Zoonosen-Monitoring of the Federal Office for Consumer Protection and Food Safety Food inspectors in Germany found germs from the group of Shiga toxin-forming Escherichia coli (Stec) in 22 of 242 wheat flour samples. Very specific Stec – Enterohaemorrhagic E. coli, EHC for short – can cause, for example, gastrointestinal problems with diarrhea or the haemolytic-uraemic syndrome, which can lead to kidney failure or blood clotting disorders in sensitive people such as small children.
Occurrence of EHEC in flour probable
Also in 2018, the official food monitoring had detected critical germs in 15 percent of wheat, rye and spelled flour samples: 50 out of 328 samples were positive, so that Federal Institute for Risk Assessment (BfR). The germs that the German surveillance authorities found in the flour samples examined can be linked to various diseases. The BfR concludes “that the occurrence of highly pathogenic EHEC variants in flour is also likely in Germany”.
Raw cookie dough as the culprit
In the past, outbreaks of the disease had primarily occurred in North America. In the United States and Canada, consumption of raw cookie dough has been implicated in many cases of illness.
You can buy raw cookie dough from us pre-packaged or as a trendy food called Cookie Dough. Raw, sweet dough is sold in small portions – similar to ice cream. According to the BfR, however, “commercially distributed cookie doughs/mixed cookie dough mixtures for raw consumption are made with pasteurized flour in Germany.” Pasteurized means heat-treated – little is known about whether this is sufficient to effectively combat germs.
Game and manure can bring germs into the grain
E. coli in food is usually an indicator of fecal contamination. The Federal Institute for Risk Assessment considers it likely that the Stec will be introduced into the grain in the field. This could have happened, for example, through organic fertilizers or during irrigation – or through ruminants such as deer and deer, where Stec naturally occur in their intestines. In the mills, the germs could also spread to other batches.
Stec bacteria also survive adverse conditions
Stec bacteria multiply at temperatures between 8 and 45 degrees Celsius. They can easily survive drought and sub-zero temperatures for weeks to months. In laboratory tests, it was noticed that some Stec strains in dried food did not die off even at temperatures of 70 degrees Celsius for five hours. “This effect is also likely for survival in flour,” concludes the BfR. The classic heat rules for food – i.e. heating the core at 70 degrees for at least two minutes – do not apply under these conditions.
Reassuring: Baking according to common recipes kills bacteria
Baking fans can still rest easy: “According to the current state of knowledge, baking flour products according to common recipes and manufacturer specifications is suitable for killing the bacteria,” according to the BfR. When asked by test.de, the BfR explained that rolls dusted with a little flour before sale also pose no risk. The amount of flour is very small and with it the probability that the minimum number of germs for an infection will be reached.
Tipp: Stiftung Warentest regularly gives tips on baking – for example how to make bread with and without yeast or how to make homemade rolls.
In the test, flour was mostly unremarkable
Also good to know: In a recent Test of 28 whole grain flours found our Austrian partners from Association for Consumer Information no stec. They examined the 11 wheat, 13 spelled and 4 buckwheat flours in addition to Stec for mold toxins and found what they were looking for: All contained deoxynivalenol – but the values were below the legally specified maximum levels with one exception. According to our Austrian partner organization, there is no acute or long-term health risk. Not even when consuming the outlier, the whole grain wheat flour from Fini’s Feinstes. In this country it is not sold.
Tipp: Some of the recommended flours are also available in Germany: wheat flour from Alnatura, dmBio and Spielberger Mühle, spelled flour from Alnatura and dmBio, buckwheat flour from Bauckhof and dmBio.
Oatmeal and muesli uncritical
However, muesli fans do not usually have to worry that oatmeal and other cereals eaten cold are contaminated with the germs. On request, the Federal Institute for Risk Assessment (BfR) informed us that these ingredients are usually steamed during production. According to current knowledge, the moist heat is sufficient to kill Stec germs. In addition, oat flakes often dry for between 20 minutes and 2 hours at 80 degrees Celsius – experts speak of Darren. According to the BfR, no outbreaks of Stec in muesli or oatmeal are known to date.
Tipp: If you make muesli flakes yourself from whole, unheated grains, you should heat them to be on the safe side.
Be very careful with flour
The Federal Institute for Risk Assessment advises consumers to be very careful with flour at home. The hygiene rules are similar to those for raw eggs or raw meat, which you can also find in our special on germs in food.
Store separately. Always store and process flour, baking mixes and raw dough separately from other foods. Make sure that no flour dust or dough residue can migrate to ready-to-eat food.
Process dough quickly. Do not leave ready-prepared dough at room temperature for long, it is best to process it quickly or at least put it in the fridge.
Don’t eat raw dough. Do not eat dough that has not been fully heated through.
Thoroughly heat foods with flour. In general, it is sufficient if the core of the food is heated to at least 70 degrees for at least two minutes when cooking, roasting or stewing. However, this does not apply to dry foods such as flour. However, if flour is mixed with eggs, milk or water to form a dough and baked according to common recipes, Stec bacteria can be killed at these temperatures.
Wash your hands. Before preparing food and after handling flour, wash your hands thoroughly with soap and water and dry them carefully.
Clean kitchen utensils and work surfaces. Use warm water and dish soap to clean bowls, plates, mixers and other kitchen tools, as well as work surfaces that have come into contact with flour.