Answers to Millers' Frequently Asked Questions

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Q: What is a standard?

A standard is a technical specification for a wide range of products including foods. A food standard is established by a country’s Metrology Department which is usually located within the Ministry of Industry. Other stakeholders including the food industry, Ministries of Agriculture, Health, or Finance, offer input into the development of the standard. A food standard does not always have legal status on its own.

A standard for fortified flour includes a list of vitamins and minerals to be included in flour. Effective standards specify a minimum and maximum level of each vitamin and mineral to add to flour. This provides a level that can be expected to have a health impact while allowing some margin so that implementation is practical.

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Q: What is a regulation?

A regulation is a legal document that is usually supported by laws developed by the government with endorsement by parliament. In many countries regulations can be developed and implemented without having to change the food law which requires the permission of parliament.

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Q: What is a guideline?

Guidelines provide recommended standards for food, but they do not always carry any legal weight. Guidelines are usually issued by normative agencies such as the World Health Organization. They can be issued for global or regional use.

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Q: What is a premix?

A premix is a powdery blend of vitamins and minerals that flour millers use for fortification. Premixes may contain an anti-caking agent  to prevent lumping. Premixes are usually prepared with diluents so they can be added to flour at a standard dosage rate such as 150, 200, 250, or 300 grams per metric ton.

A premix allows a miller to add several micronutrients at the same time to flour. A standard premix specification also allows millers to compare prices from different suppliers on a standardized basis which will prevent pricing and costing errors.

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Q: Who supplies premix?

A number of reputable premix suppliers are located around the world. These companies are based in North and South America, Europe, Middle East, Africa, and Asia. Many companies have local agencies operating in the region or country level.

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Q: What is a feeder and what does it do?

Stainless steel feeders accurately add premix directly to flour. The feeder is equipped with a variable speed drive motor which has a discharge mechanism and a hopper agitation device attached with a gearbox. The agitation device provides an even, consistent flow of premix into the flour.

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Q: What types of feeders are there?

Feeders have one of three discharge systems: Screw discharge, disk discharge and drum discharge.

Most modern feeders use the screw discharge system. The size of the discharge screw and the speed range of the variable speed motor allow for a wide range of discharge rates. The feeders can be connected electronically or electrically to the main control panel or microprocessor that controls the flour mill. In addition, the feeder can be equipped with load cells which convert the feeder from a volumetric feeder into a gravimetric or loss-in-weight feeder.

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Q: How do you know how to get the right size of feeder?

Feeder size is determined by the mill’s flour production rate range and the prescribed addition rate (in grams per metric ton) of the premix. Choose a feeder size that will operate at a discharge rate of between 30 to 70% of the full speed of the feeder. If the feeder is operating outside that range, the chances for more variation in discharge rates will be higher.

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Q: How is flour fortified at the mill?

The fortification process is usually a continuous process that adds premix to flour as it is being produced. In some cases, fortification takes place in a high speed blending system following the flour milling process. In this case, this system is usually installed as part of a new flour mill.

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Q: Where is the feeder installed?

The feeder is usually on top of the final flour collection conveyer where premix drops by gravity into flour as it move through the conveyer.

When an existing mill has to install a feeder to begin fortification, there may not be room on top of the conveyer for a feeder. In this case the feeder can be installed on the same floor as the conveyer. The feeder is connected to the conveyer using a blowline which blows the premix from the feeder into flour.

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Q: How do you ensure that the feeder is operational?

The feeder must consistently deliver premix to the flour conveyer at a point that allows for sufficient mixing time so that the premix is evenly dispersed in the flour. Tips for doing that are:

  • Place the feeder more than three meters from the discharge end of the conveyer where the premix is added.
  • Interlock the feeder with the mill control panel or the first break sifter or the conveyer motor so that if the mill stops, the feeder stops.
  • Equip the feeder with a low level alarm indicator so that the feeder does not run out of premix.

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Q: What quality control and quality assurance procedures are needed for flour fortification?

The steps provide quality control and quality assurance at the flour mill. See more details in our website section on Monitor for Quality and Impact.

  • Store premix in a dry, secure location and away from direct light to prevent degradation of the vitamins.
  • Calibrate the feeder on a regular basis and whenever the premix composition is changed or the supplier is changed.
  • Calculate the feed rate for the feeder to establish an acceptable dosage range of +/- 5% of the target addition rate for premix.
  • Conduct the check weighing process of the feeder regularly. This involves weighing the amount of premix discharged by the feeder over one to two minutes then comparing it to the weight of premix expected to be discharged over that period.
  • Perform the iron spot test at least three times per eight-hour shift.
  • Send monthly samples for full analytical testing of all the nutrients added to flour.
  • Use an inventory control system to verify that the amount of premix being used is close to the specified or target rate.

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Q: What does fortification cost the milling industry?

To fortify flour, the miller has the one-time expense of buying feeders plus the on-going costs of buying premix and supplies for quality control and quality assurance testing. Some costs may be associated with staff training.

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Q: How much does premix cost?

The cost of the premix is most affected by the number of vitamins and minerals included and the quantity of each nutrient. Vitamin A is the most expensive nutrient to include in flour.

 The following table gives an indication of the premix cost:

Nutrients in Premix Cost Range per Metric Ton of Flour (US dollars)

Iron and folic acid


Iron, folic acid, B group vitamins


Iron, folic acid, B group vitamins and vitamin A


These estimates should NOT be used as official market prices. These prices do not reflect import duties and value added tax (VAT). Millers should request premix price quotations from more than two suppliers to ensure competitive prices.

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Q: What other factors affect the cost of premix?

Prices are affected by supply and demand worldwide. Vitamins and minerals are also used for animal feed preparations, and premix cost is affected by the demand for animal feed use. The cost of transportation from the supplier’s location via air freight or surface is also a factor. Import duties can range from 15-45% of the price of the premix.

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Q: How much do feeders cost?

Feeder costs have a wide range. Assuming the rated capacity of the flour mill is greater than 50 metric tons of wheat ground per 24 hour period, a volumetric manual operation feeder can cost from US $3,000 to $10,000. For the same mill, the cost for a loss in weight automatic feeder with linked microprocessor control can range from US $15,000 to $35,000.

These prices should NOT be used as official market prices. These prices do not reflect the costs of import duties and value added tax (VAT). Millers should request feeder price quotations from more than two suppliers to ensure competitive prices.

When a new mill is being constructed, the additional cost of automatic loss-in-weight feeders is very low compared to the capital cost outlay for a new mill. New mill owners should always consider the use of loss-in-weight automatic feeders in this instance.

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Q: What is the cost of installing feeders?

Typically, installing a feeder costs 10-15% of the feeder price.

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Q: Is this feasible for small mills?

While fortification is technically feasible in very small mills, ensuring consistency is challenging. Very small mills (less than 10MT per day) are usually located in rural and peri-urban areas. If they are fortifying flour with assistance from non-governmental organizations and development agencies, the agencies provide training and supervision required to fortify flour. Trying to bring this program to national scale is challenging. 

Some countries, such as the Kyrgyz Republic, have successfully started flour fortification in mills where capacity ranges from 10 to 30 metric tons per day. The mills use a small feeder which consistently fortifies flour adequately. This feeder is available from a supplier in China at a reasonable cost. Feeders designed for larger mills are too expensive relative to the cost of the small mill equipment.

See additional resources for fortifying in small mills.

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Q: Does fortified flour change its baking qualities? Does fortification affect the color, smell, and taste of foods made with fortified flour?

When appropriately implemented, fortification does not impact the organoleptic and food technology attributes of flour when used in foods such as baked goods, breads and noodles. See a review of literature published on this subject.

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Q: What is the role of government in monitoring and evaluation?

The milling industry and the government share responsibility for ensuring that the flour is fortified correctly and consistently. The government is responsible for:

  • Developing and publishing fortified flour standards and regulations
  • Enforcing the regulations through effective inspection procedures and audits
  • Controlling and enforcing the applicable standards on both national production of flour and imported flour.
  • Conducting routine analytical testing of flour samples from both the milling industry and the marketplace to verify compliance to the standard and regulations
  • Evaluating the impact of the fortification program and making changes as needed

See more details in our website section on Monitor for Quality and Impact.

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Q: Does fortification present a trade barrier?

Flour fortification specifications are technical specifications that also include moisture content, protein content, amylase activity, and baking performance and quality tests. Many different flour specifications are already in place, and they do not prevent trade between countries.

The World Trade Organization allows member states to implement measures to protect human health. See more information in our FAQ for Finance.

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