Extrusion Bolsters Food Security in Africa

If you are in the extrusion business in Africa – or anywhere else for that matter – this paper published in the April edition of Food Technology ( is a ‘must-read’.

It’s based on a presentation at last year’s ExtruAfrica event in South Africa. The authors – Kalep Filli, Afam Jideani, and Victoria Jideani explain clearly why and how extrusion technology can contribute to food security.

The cereal grains of Africa, such as sorghum, millet, rice, maize, fonio and tef, are widely consumed as the main staple meals but they are limited in protein quantity and quality. Extrusion enables the use of inexpensive, locally-grown sources of protein – soybean, cowpea, peanut, bambara nut and other legumes – to fortify them and make read-to-eat nutritious foods.

The authors cite foods that have been developed by extruding yam and groundnut, millet and soybean, sorghum and soybean, sweet potato and soybean, and fura, a traditional West African snack produced from millet and sorghum.

“There is no doubt that the application of extrusion to traditional African foods can lead to the diversification of new and novel foods, which can result in increased usage of the technology for sustainability,” they say.

They cite at least ten advantages of extrusion cooking:

  1. Gelatinization of starch which enhances digestibility
  2. Protein denaturation enhancing digestibility
  3. Inactivation of thermally labile growth inhibitors such as trypsin inhibitors
  4. Inactivation of deteriorative enzymes (lipases and oxidases) resulting in products with better storage stability
  5. Destruction of natural toxicants, such as goitrogens, haemagglutinins, glycosides
  6. Product instantization, which can be prepared quickly, saving time and equipment
  7. Reduced cooking time, thus enhancing the retention of vitamins and nutritive value of the foodstuff
  8. Shelf stability of extrusion-cooked foods, thus ensuring nutritious food year-round
  9. Fuel costs associated with normal, lengthy cooking are negligible with extruded foods
  10. Pasteurization/sterilization of food – extrusion cooking reduces or eliminates contaminants.

In the case of fura, for example, the traditional product has 60-75% moisture content and shelf life of 2 days at most, but when fura is extrusion cooked, moisture content is below 7% and the product does not require refrigeration. The inclusion of soybean with pearl millet improves the protein quality and quantity of the fura by greatly increasing lysine content and availability.

The authors summarize: “Extrusion processing offers the possibility of better storage stability, added value, lower transportation cost, generation of employment, and creation of new markets in the food and feed sectors.”

Several African universities and Ministries of Agriculture are now paying more attention to extrusion, with research, product development and teaching activities. Kenya, Nigeria, South Africa and Uganda are all active in this area. If you are aware others, please let us know.

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