From Mars to Mali: Purdue’s Small Extruder

A small extruder initially developed by Purdue University for a NASA mission to Mars is now making a big impact on African entrepreneurs. This innovative tool allows them to efficiently process low-cost, local crops like millet and sorghum into high-demand instant cereal products, such as couscous and instant porridge, unlocking new income opportunities.

Originally designed in the early 2000s by Purdue professors Martin Okos and Osvaldo Campanella with NASA funding, the single-screw extruder was intended to process food grown on Mars, with capabilities to cook grains and soybeans and extract oil. Though it has yet to be used for space missions, its compact size of about four feet in length and its relative affordability presented another opportunity. The extruder could help small- to medium-sized food enterprises in developing countries increase their output and reduce the drudgery associated with traditional production methods. With this aim, Purdue researchers adapted the extruder by further simplifying its operation and reducing the cost to about one-tenth that of a commercial extruder.

Food science professor Bruce Hamaker and former graduate student Moustapha Moussa have been introducing the extruder, licensed by Technochem International, in Africa through USAID’s Feed the Future Innovation Lab for Food Processing and Post-Harvest Handling, based at Purdue. Moussa’s presence in West Africa has helped him connect with entrepreneurs and test the extruder in real-world settings.

The recent growth of Africa’s economy and middle class has driven increased demand for convenient foods like instant porridge and couscous. However, locally made instant cereal products are often scarce in retail markets due to inefficient and time-consuming traditional production methods. As a result, costly imported wheat-based products have largely filled this gap.

The process of making traditional West African pearl millet couscous, for example, can take up to three days. The Purdue extruder significantly increases productivity, boosting output from 50 kg per day to about 350 kg per day using the same amount of labor (Moussa et al. 2022). Flour and water fed into the extruder are quickly mixed and cooked as a rotating screw pushes the mixture through the barrel, generating heat through friction. Then the extrudate is dried and milled to the desired particle size. Reduced rancidity and improved taste, color, texture, and consistency are notable product benefits.

Instant porridge, made similarly but to a finer grind, is the best-selling extruder product, particularly popular among mothers who buy it for their children. Many of these porridges are fortified, as the extrusion process makes it easy to incorporate nutrient premixes and natural fortificants like hibiscus, Moringa, and baobab.

A hub-and-spoke system lets users exchange information about new products and processes, with insights flowing from central food innovation centers (the hubs) to rural food processing centers (the spokes). Purdue extruders are used in Niger, Burkina Faso, Mali, Senegal, Tanzania, and Kenya.

The project has increased production efficiency and revenue for small food businesses, improved public access to affordable food, boosted farmer incomes, and strengthened the supply chain.

Recent disruption of USAID funding for Feed the Future Innovation Labs at land-grant universities across the country has created an uncertain future for those involved in this and many other food security projects.ft