Extent of decortication and quality of flour, couscous and porridge made from different sorghum cultivars

Sorghum grain was decorticated to remove 10%, 20%, 30% and 40% of the kernel for the purpose of improving flour colour, couscous colour and yield, and porridge texture. Flour lightness increased while yellow colour decreased with increased extent of decortication. Processing of the flours into couscous caused a considerable drop in lightness and increased yellow colour in couscous at all levels of decortication. As decortication level increased, couscous colour became lighter. Yellow colour progressively increased up to 30% kernel removal and dropped at 40%. Couscous yield, as measured by the proportion of particles of 1-2 mm size, also increased up to 30% kernel removal. This improvement in yield was attributed to decreased proportion of bran as indicated by ash content. However, the yield dropped at 40% kernel removal due to formation of large chunks of agglomerated flour particles. Thick porridge became harder as decortication level increased and this was strongly associated with the concomitant increase in starch concentration. Overall, this study defined the decortication levels necessary to improve the couscous colour and yield, and texture of porridge made from different sorghum cultivars.