Out of Africa: Sorghum, the sustainable cereal

Out of Africa Sorghum flourishes in the sub-Saharan climate

Professor Peter Belton.
University of East Anglia.

Professor John Taylor and Dr Gyebi Duodu.
University of Pretoria.

Dr Clare Mills and Dr Chunli Gao.
Institute of Food Research.

Professor Peter Shewry, Dr Jane Forsyth and Emmanuel Chamba.
Rothamsted Research.

Sorghum is the world's fifth most important cereal. It is grown in semi-arid regions of Africa, but the advantages it confers in being well adapted to the harsh climate and naturally resistant to many pests are to an extent outweighed by significant drawbacks. The protein in sorghum grains - kafirin - is less digestible than other cereal proteins. It is also less popular than maize, which is less well suited to the sub-Saharan climate.

EU-funded researchers are using modern cereal science to find out why sorghum is so indigestible. Although they do not yet understand all the reasons, the scientists have used what they have learned to improve the ways that the crop is currently processed. Isolating the protein, purifying it, and subjecting it to enzymatic assays, nuclear magnetic resonance technologies and different kinds of processing and cooking has revealed better ways for preparing it. As a demonstration project, they have also been able to produce new tastier and more nutritious sorghum food products, such as bread and weaning foods. Consumer tests have shown that these products are popular with the locals.

'You can find out for yourself what African sorghum porridge tastes like, as we shall be cooking it on the exhibition stand,' says Gyebi Duodu. 'Our research has shown that the precise way we process and cook the grain can make a huge difference to its nutritional value. Changing the conditions for fermenting or malting the grain means the kafirin protein gets pre-digested before it goes in the pot. This makes it tastier and more nutritious.'

The team has shown that extruding (dry cooking) sorghum flour before adding it to weaning foods can produce a formula food that is highly nutritious and still liquid enough for babies to eat. They have also produced a new recipe for bread using malted or fermented sorghum.

For Peter Belton, coordinator of the collaboration, one of the most exciting parts has been to use modern science to improve sorghum preparation at a domestic scale. 'From the start, this project has been user-driven,' he explains. 'We wanted to use modern science to improve existing technologies.'

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