Fortification of powdered products

The addition of vitamins B1 and B2, niacin, iron and calcium to wheat flour is a common practice in many countries. However in powdered products as this, it is technologically feasible to add other vitamins and minerals as well.

Tips for selecting a suitable premix...

The below points need to be considered for selecting a premix/ fortificant that is appropriate for the enrichment of this products category.

• Vitamin A

The form of vitamin A most commonly used in the fortification of flour is dry stabilised vitamin A palmitate powder form.

• Water soluble vitamins

The water soluble vitamins (thiamin, riboflavin, niacin, pyridoxine, folate and calcium pantothenate) are used in pure crystalline form. The mononitrate salt of thiamine is preferred for this use.

• Iron

Iron is normally used in its reduced elemental form or fumarate. Ferrous fumarate is used in the fortification of US wheat flour. Ferrous sulfate added to maize meal provokes blue or green discoloration upon cooking. Ferrous sulfate is not recommended for use in wheat flour.

• Magnesium

Magnesium inclusion is not recommended as it affects taste and structure of bread, biscuits.

• Iodine

Iodine as 2-4 ppm KIO3 in flour does not affect the quality of the bread or biscuits.

Adding the premix/ fortificant in the powdered vehicle

In powdered products the addition of the premix/ fortificant can be performed via batch mixing, two-stage mixing or continuous metering.

When continuous metering is not feasible or effective In the fortification of powdered products the two stage-mixing has proved to give better homogeneity at the final product, where the required nutrient mixture is mixed with an appropriate diluent to produce a preblend, which is then accurately metered into the flour.

For Super Cereal products, which undergo roasting, IR processing, extrusion cooking or drum-drying, it is recommended to add minerals and vitamins to the grinded products at the end of the process, prior to packing stages.

Attention is required for the homogeneous incorporation of dry fortificants to dry foods. Careful selection of the physical characteristics of the fortificant compound is important so as to ensure adequate mixing and to minimise segregation on storage. A Coeficient of Variation should be calculated to ensure that mineral and vitamins premix is homogeneously distributed in the finished product.

Fortification / Fortificant losses during:

• Manufacturing of Super Cereals

There losses during the Super Cereal processing are negligible, provided that the premixes are added after the thermal processing and prior to packing.

• Storage of Super Cereals

• Vitamin A: 20% loss after 6 months, 50% after one year.
• Vitamin C and B1: 20% loss after 6 months
• Vitamin B2: stable to storage conditions.

• Storage of fortified flour (wheat/ maize)

The vitamin/iron premix demonstrates excellent stability on storage. The flour enriched with both premixes demonstrates excellent stability on storage at room temperature.

Under conditions of accelerated storage at elevated temperature (45 °C), however, there is substantial loss of vitamin A beyond 4 weeks of storage. Parrish et al. (1980) also reported good stability of enriched wheat flour stored at room temperature, but about 50% losses in flour stored at 40 °C for 6 months.

Losses of vitamin A in corn meal on storage at room temperature for up to six months are greater than with wheat flour but still remain below 20%.

• Cooking of fortified flour

The inclusion of calcium and magnesium in the premix adversely affects vitamin A retention during the baking process of flours.

• Cooking/ Preparation of Super Cereal meals

Losses during preparation will vary according to the mode of preparation. Making a porridge or roasting will not have the same effect on retention of minerals and vitamins.