Food Safety in Flour Mill

06 March 201812 min reading

“Flour milling company’s intent should be to produce under conditions that will lead to safe and quality products. The process is designed to ensure that no product leaves the facility and enters commerce that is unsafe or adulterated. An effective food safety system requires management commitment, proper resources, effective training, employee dedication, and follow up. All food safety systems are living and breathing. They will be ever changing, needing to be updated and revised.” 



Food Safety Consulting, LLC Consultant and Certified HACCP Trainer Email:

Food Safety is the single most important aspect of food production. A few years as a Food Safety Consultant I was given the challenge to assist three large flour mills achieve FSSC 22000 Certification. Based on this experience and my background I was asked to write this article on food safety for Miller Magazine.

Flour mills are wonderful producers of food. They are highly automated while producing large volumes of flour. One place I consulted at had only 25 employees producing 800,000 pounds of flour daily. These facilities have enclosed systems that transfer the wheat from different sections of the plant through piping and the use of the various processing machines. It is a very efficient process.

However as I stated earlier they do present a challenge. First is the nature of cleaning the facility. Water cannot be used as in most food plants where they spray down equipment and use sanitizers. One reason for the lack of water use is that some of the mills have wood used throughout their plants. Another reason is that water upon touching flour will create an untidy sanitation problem itself. Thus all cleaning must be dry form using brooms and brushes using a predetermined S.S.O.P.

Another challenge at the flour mills is lack of personnel. While it is a great value for the company owning the flour mill to be able to use few people, it makes a hardship in regard to food safety implementation. In order to get facilities certified for GFSI schemes and to meet other food safety standards requires thorough training of the employees. Along with training there is a need to identifying which individuals will be responsible for the tasks related to food safety. All employees receive basic food safety training while specific persons are given training related to their responsibilities.

The flour mills produce is a “Ready to Cook” product. This means it has to be processed by cooking prior to consumption. This is a major advantage over being a ready to eat type product. Thus if there is a microbiological contamination it should be eliminated at the bakery that receives the flour. As for chemical hazards there are not many chemicals used in the facility, those that are can be safely stored to prevent a contamination hazard.

The most severe food safety hazards at flour mills are the physical type. These can include various forms of metal, bugs, wood and too many others too numerous to mention. The first point of physical hazard prevention begins at receiving inspection when the wheat is unloaded. At this point the receiving person can prevent any visible items from entering the food chain. One flour mill found a tool box upon unloading.

After the wheat proceeds into the mill they have scourers, roll stands, sifters, magnets and metal detectors to help identify and eliminate the physical hazards in the flour. All of these machines should have a work instruction and be regularly monitored and be on preventative maintenance schedule.

Pest Control is capitalized as it is of critical importance at flour mills. Many pests including rats, mice, birds and others are commonly found in and around flour mills. Companies must have a vibrant and effective pest control program to protect their food products from being contaminated. They must have a good pest control company and PCO (Pest Control Operator). The pest control firm should have sufficient traps inside at adequate spacing, on each side of all man and dock exit doors and checked weekly. Outside perimeter must have bait station spaced appropriately and monitored at a minimum of monthly. Additionally all PCO’s should have liability insurance, applicator licenses and training certificates. They must have maps of the locations of all traps and bait stations, sighting logs, service reports, SDS and chemical usage form. On the following sections of my article I cover in more detail an assessment of the Biological, Chemical and Physical Hazards of a flour mill along with the milling equipment used.

As stated flour mills are challenging but highly effective food producing facilities. I assisted the three plants where I consulted in them becoming FSSC 22000 Certified. Programs were written, employees were identified to implement them, training was completed and the system was put in place.

An effective food safety system requires management commitment, proper resources, effective training, employee dedication, and follow up. All food safety systems are living and breathing. They will be ever changing, needing to be updated and revised. FOOD SAFETY HAZARD JUSTIFICATION SUMMARY Below are three categories of potential hazards flour mills should considered for their HACCP Plan. In each category specific hazards are listed and an explanation of why these hazards are or are not considered significant food safety hazards.

1.Biological Hazards *Deoxynivalenol:Deoxynivalenol is more commonly known as Vomitoxin is produced by several mold species of the genus Fusarium. Vomitoxin is naturally occurring in wheat depending on moisture available. In dry growing years Vomitoxin is not prevalent but in wet growing years it can be present. FDA has a guideline of 1 ppm on finished flour. FDA states that Deoxynivalenol is not completely avoidable in wheat but levels are reduced in the milling process. Deoxynivalenol is a significant food safety hazard. Control measures at receiving (testing) help to reduce or eliminate this hazard to an acceptable level. Loads of wheat are rejected if they test above set levels for Vomitoxin.

Salmonella: Salmonella from wheat has been linked to food safety outbreaks in flour. Salmonella is a recognized potential biological contaminant in wheat. Studies have shown that the rate of wheat flours containing Salmonella can be as great as 1.3%. Salmonella poses a significant food safety hazard in raw flour. However if baked at 375° F. for 17 minutes or more Salmonella and any other pathogen will be destroyed.

Toxic Seeds: The findings of toxic seeds in incoming ingredients or raw materials in the United States is infrequent Although some geographic areas such as Australia have the potential risk of contamination, toxic seeds are not evidenced in areas where in the major grain growing areas in the USA. Therefore toxic seeds have been determined to not be a significant hazard. 2.Chemical Hazards Fungicides, Pesticides and Insecticides: There is a potential of higher than acceptable levels (EPA/FDA guidelines) of Fungicides, Pesticides and Insecticides on incoming wheat. This is due to the fact that farmers apply this to crops and storage bins in order to control Vomitoxin, mold, pests and insects. In absence of control at wheat receiving, there is a potential for contamination by these chemicals. Therefore Fungicides, Pesticides and Insecticides can be deemed a significant food safety hazard.

Soy Protein: Soybeans contain a small but newly very significant {2S Albumin} storage protein. Due to farming practices and crop rotation (farmer’s plant soybeans in field one year then switch to wheat or other grains next year) there is a potential for cross contamination of soy protein in the incoming wheat. Soy Protein is thus can be considered a significant food safety hazard.

Grease, oil and other lubricants: Grease and oil are used as lubricants for moving parts on mill equipment. There is a potential that grease (food grade) or oil may contaminate the product in absence of control measures taken such as preventative maintenance, equipment monitoring and proper storage of chemicals. Thus grease, oil and all other lubricants can be considered a significant food safety hazard.

3. Physical Hazards Glass, Metal, Stones, Tools and Wood: Wheat plants commonly find foreign material in raw incoming wheat. Farmers pick up glass, metal, stones, tools, wood and other items during the harvest process. In the absence of control measures at receiving (inspection), preventative maintenance, metal detection, magnets, sifters and equipment monitoring there is potential for foreign material contamination. Foreign material therefore can be considered a significant food safety hazard.

* Vomitoxin, also known as deoxynivalenol (DON), is a type B trichothecene, an epoxy-sesquiterpenoid. This mycotoxin occurs predominantly in grains such as wheat, barley, oats, rye, and maize, and less often in rice, sorghum, and triticale. The occurrence of deoxynivalenol is associated primarily with Fusarium graminearum (Gibberella zeae) and F. culmorum, both of which are important plant pathogens which cause fusarium head blight in wheat and gibberella or fusarium ear blight in maize. A direct relationship between the incidence of fusarium head blight and contamination of wheat with deoxynivalenol has been established.[1] The incidence of fusarium head blight is strongly associated with moisture at the time of flowering (anthesis), and the timing of rainfall, rather than the amount, is the most critical factor. However, increased amount of moisture towards harvest time has been associated with lower amount of vomitoxin in wheat grain due to leaching of toxins.[2] Furthermore, deoxynivalenol contents are significantly affected by the susceptibility of cultivars towards Fusarium species, previous crop, tillage practices, and fungicide use.[3]

F. graminearum grows optimally at a temperature of 25°C and at a water activity above 0.88. F. culmorum grows optimally at 21°C and at a water activity above 0.87. The geographical distribution of the two species appears to be related to temperature, F. graminearum being the more common species occurring in warmer climates. Deoxynivalenol has been implicated in incidents of mycotoxicoses in both humans and farm animals.

When compared to other trichothecene mycotoxins which can form in grains and forages, vomitoxin is relatively mild. Reduced feed intake, with its accompanying decrease in performance, is the only symptom of vomitoxin toxicity livestock producers will likely encounter. This response to vomitoxin appears to occur through the central nervous system. Vomitoxin belongs to a class of mycotoxins (tricothecenes) which are strong inhibitors of protein synthesis; exposure to vomitoxin causes the brain to increase its uptake of the amino acid tryptophan and, in turn, its synthesis of serotonin. Increased levels of serotonin are believed to be responsible for the anorexic effects of DON and other tricothecenes. Irritation of the gastrointestinal tract may also play a role in reducing feed intake, and may also partially explain the high incidence of paraesophageal stomach ulcers observed in sows during feed refusal.

• Human foods: Vomitoxin is not a known carcinogen as with aflatoxin. Large amounts of grain with vomitoxin would have to be consumed to pose a health risk to humans. The U.S. Food and Drug Administration has established a level of 1 ppm (parts per million) restriction of vomitoxin.

• Companion animals: Dogs and cats are restricted to 5 ppm and of grains and grain byproducts and the grains are not to exceed 40% percent of the diet.

• Livestock and farm animals: In animals and livestock, vomitoxin causes a refusal to feed and lack of weight gain when fed above advised levels. Restrictions are set at 10 ppm for poultry and ruminating beef and feedlot cattle older than four months. Ingredients may not exceed 50% of the animal’s diet. Dairy cow feed limits are set at 2 ppm.

FLOUR MILL FOOD SAFETY Flour milling company’s intent should be to produce under conditions that will lead to safe and quality products. The process is designed to ensure that no product leaves the facility and enters commerce that is unsafe or adulterated. Inspection/DON Testing Milling companies should perform visual inspection (following a work instruction) on each delivery vehicle that brings wheat to the mill. The wheat should be probed and tested for moisture. The mill will perform a Don/Vomitoxin test on loads. All information shall be filled out on Incoming Material Receiving Form.

Scourers Flour mills have scourers for cleaning the wheat. The scourers efficiently remove impurities such as dust, sand, mold, clods of soil and any other non-wheat material that adhere to the grain, thus providing ideal preparation for grinding. The scourer significantly improves product hygiene – by reducing the microbial count (bacteria, fungus etc.) as well as minimizing the presence of insects or their fragments.

Magnets The mills have magnets to keep product and equipment free from metal fines and tramp metals. These devices are used to remove metal particles from the wheat and/or flour going through the process. Magnets are monitored and checked using work instruction.

Enclosed System Flour mills have an enclosed processing system. The wheat and/or flour is transferred by a series of pipes from roll stands to airlocks to cyclones to sifters throughout the mill until it either goes into storage or is packed into bags or totes, or is loaded into bulk trailers. This makes it a very safe process.

Sifters Most mills have many sifter sections. The sifters remove oversize or foreign materials and de-dusts the material to meet final product specs. The sifter controls both oversized and undersized material. They utilize a sieve to effect particle size separation through the use of finely meshed bolting cloths. They are used for grading grains as per length, width size, immature grain, broken sizes. The mills should use a work instruction in regard to cleaning and inspecting sifters.

Metal Detector Mills will utilize metal detector (s) throughout the process. These are typically set for detecting 2.0 mm. stainless steel in 50-100 lb. bags of dry product. The system also will detect ferrous and non-ferrous metal as small as 1.5 mm. Metal detection in a bagging area can be a Control Point or Critical Control Point at the mill’s discretion. The mill should use a work instruction in regard to the metal detector operation.

Conclusion Summary: The flour mills can through their use of inspections of product, the cleaning process they expose to the incoming wheat, the use of their scourers, roll stands, magnet and metal detection devices throughout the mill, numerous sifters and the fact that they have an enclosed system with their piping conveyance of wheat and/or flour can be confident that they produce a safe and high quality flour product.

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