2019-12-09T18:11:42Z (GMT) by Moustapha Moussa
Abstract Sorghum and millet crops are the staple foods for most people in the Sahelian region of West Africa. Preparation of millet and sorghum foods are labor-intensive and time-consuming. This thesis work was conducted with the goal of developing competitive and innovative processes to make better quality and higher quantity of extruded couscous, and instant, or fast cooking, millet food products to improve markets for smallholders’ famers, improve nutrition, and to meet the changing demands of local consumers in West Africa. Processing conditions, of a low-cost single screw mini-extruder were assessed and optimized. The process has the advantage of shortening production steps, and time, of making number of products with appealing appearance, good taste, and texture, and designed for the preferences of local consumers. The products can be reconstituted by adding hot or tap water. Results of the first study on a newly developed extruded couscous indicated that consumers in general preferred it, that it was fast cooking couscous, and credited it to be smoother in texture than the traditionally-prepared couscous. It had 10x the daily yield as couscous typically prepared for commercial sale by women in a processing unit. The smoother texture was attributed to the presence of starch fragments of somewhat lower molecular size, than in the control couscous, as illustrated by size-exclusion chromatography analysis of the hot-water dispersed starch. In the second study, the extruder was used to make instant porridge flour, and locally available roasting process was optimized to make a fast cooking porridge flour, and each flour was formulated using natural and locally obtained plant fortificants to nutritionally enhance cereal-legume-fortified flours. Results of consumers sensory tests and textural characterization by RVA and dynamic oscillatory rheometry of fortified porridge samples revealed that the innovated formulas had better viscosity, taste, and flavor, and were more preferred by children and their mothers than food aid vitamin-mineral premix fortified flours distributed at rural government health centers. Bioaccessibility of provitamin A carotenoid and lycopene derivatives, including lutein, α- and β-carotenes, using an in vitro digestion system coupled with a HPLC-C30SHORT column, shown that the formulated fortified flour samples had high bioaccessibility values of provitamin A carotenoids, lutein, and α- and β-carotenes. In the third study, rheological results indicated that instant tuwo (thick) and fura (thin) porridges had better viscosity and textural attributes (creamy, elastic, gelling) compared to traditional corresponding porridges. In the fourth

study, a home use testing (HUT) of instant tuwo and fura porridges in Niamey, Niger indicated that overall consumers’ acceptability was good. In a market test conducted in Niamey over 20 weeks, in collaboration with local cereal processors and distributors, showed repeat purchases with good frequency of sale of instant tuwo and fura porridges that have generated about 1/3 in total sales of 35 products related millet and cereal based foods in the period. In conclusion, the low-cost single screw extruder has the potential to catalyze and increase demand and diversification of uses of millet grains, to develop market-driven nutritious and healthy grain-based foods, to benefit smallholders’ farmers, and favor growth of small- and medium-scale entrepreneur processors in West Africa.