Protein, anti-nutrient and sensory qualities of complementary food made from malted finger millet (eleusine coracana l.) and cowpea (vigna unguiculata l.) composite flour

Abstract

Protein-energy malnutrition remains a huge problem for children in sub-Saharan Africa. Kenyan children are no exception. These children rely on cereal porridge such as finger millet (Eleusine coracana) for nutrient supply. Cowpea (Vigna unguiculata), a locally available nutritious legume, could be an excellent complement to lysine-deficient millet diets. Therefore, the present study aimed at innovatively improving the protein quality and sensory properties of the complementary food, by evaluating the effect of malting on improved finger millet genotypes (U15, P224, KNE741, KNE629 and Snapping green) and compositing with cowpea to enable selection of the best varieties with superior nutritional credentials post process. Prepared selected finger millet and cowpea flours were composited in a ratio recommended by the World Health Organisation to deliver minimum protein content for complementary formula with, 0% cowpea as the control. Impact of malting and compositing on protein and anti-nutritional compounds was determined in terms of protein content; in vitro protein digestibility, amino acid profile and anti-nutritional compounds such as phenolic compounds, condensed tannins and phytic acid were assessed for recommendations in product development. The best levels of substitution were evaluated via descriptive sensory analysis. KNE741 and Snapping green finger millets showed superior qualities in terms of protein and tannin contents. Compositing with precooked cowpea increased in vitro protein digestibility in raw flour by about 4-8%. In addition, phenolic compounds, tannin content, and phytic acid content notably decreased by 40%, 18%, and 44%, respectively, after compositing with improved malted finger millet and precooked cowpea at 0%, 10.32%, 21.26%, and 32.75%. Cooking of malted and composited flours resulted in a decrease in total phenolic compounds, condensed tannins and phytic acid, by 22%, 1%, and 13%, respectively, with concomitant increase in in vitro protein digestibility. The first three principal components accounted for approximately 75% of the variations in sensory attributes. Among the sensory attributes, astringency and stickiness were more pronounced in KNE741 than Snapping green finger millet variety. Increase in malty flavour and aroma after malting finger millet corresponded to reductions in texture attributes and astringency. In addition, compositing with precooked cowpea flour beyond 21.26% resulted in distinct cooked cowpea flavour. This study shows that, malting of finger millet and compositing it with precooked cowpea has the potential to address protein-energy malnutrition among under five children in sub-Saharan Africa. However, compositing with higher levels of precooked cowpea requires flavour masking.