Internal Quality Control
Internal monitoring for flour fortification includes the process control steps that premix providers and flour millers take to comply with country standards for nutrients in flour.
Elements of internal monitoring, following good manufacturing practice (GMP) and hazard analysis and critical control points (HACCP), include:
- Premix Production: Premix is the powdery blend of vitamins and minerals added to flour during fortification. Reputable premix manufacturers use high-quality nutrients and follow the industry’s best practices. See a list of premix suppliers that have met quality requirements set by the Global Alliance for Improved Nutrition (GAIN).
- Premix Shipment: When premix is delivered, flour millers inspect the box to be sure the content has not been damaged in shipment. The miller also confirms that the nutrient content indicated on the certificate of analysis matches what was ordered.
- Premix Use: A simple step to ensure quality is to keep accurate records of the amount of premix used regularly compared to the rate of flour produced. If flour production remains constant but the quantity of premix varies greatly, then there is likely a problem in the fortification process.
- Feed Rate: Equipment called a feeder or dosifier adds premix to flour at pre-determined rates. The feeder should be checked hourly and refilled if it is low. In a process called check weighing, a miller weighs the amount of premix discharged by the feeder over one to two minutes then compares the amount to the weight of premix expected to be discharged over that period. We recommend that this be checked at least once in every eight-hour shift.
- Iron Spot Test: This simple, rapid test indicates qualitatively whether iron has been added to the flour. A solution of hydrochloric acid is added to a flour sample, and in a few minutes, dark spots will appear if the flour has been fortified with iron. The intensity of the color is obviously different when flour is fortified with iron than when the spot test is reacting to iron that is naturally present in wheat.
The presence of iron in fortified flour is considered a proxy for other nutrients that were included in the premix. The iron spot test is formally Method 40-40.01: Iron Qualitative Method as approved by the American Association of Cereal Chemists (AACC).
The spot test works will for most iron compounds such as ferrous sulfate, ferrous fumarate, and electrolytic iron. When flour is fortified with sodium iron EDTA (NaFeEDTA), the test works as long as hydrogen is not used as a reagent. See section 5 of the Flour Millers Toolkit for instructions.
- Outside Testing: Periodically millers send fortified flour samples to laboratories to be sure that all the specified nutrients are present in the correct amounts. This requires sophisticated equipment and careful adherence to protocols because the level of vitamins and minerals is very small compared to the volume of flour. Some milling associations or large milling companies have centralized laboratories for this work. Premix suppliers have laboratories for testing the nutrient content of their products, and they may provide flour testing services to their customers.
Dark spots appear in flour that has been fortified with iron in the simple procedure known as the iron spot test.