Effects of Fermentation and Extrusion on the Proximate and Organoleptic Properties of Cowpea-plantain Flour Blends

This study was conducted to investigate effects of fermentation and extrusion on the chemical and sensory properties on blends of unripe plantain flour and cowpea flours. Three ratios (100:0, 80:20 and 60:40) of unripe plantain and cowpea flour were fermented and extruded. A total of 18 organisms were isolated during fermentation of plantain: cowpea blends. They include eleven (11) bacteria, four (4) moulds and three (3) yeasts. These are Bacillus subtilis, Bacillus licheniformis, Micrococcus luteus, Enterobacter cloacae, Proteus mirabilis, Staphylococcus aureus, Leuconostoc mesenteroides, Lactobacillus bulgaricus, Lactobacillus casei, Lactobacillus fermentum, Lactobacillus lactis, Aspergillus niger, Aspergillus flavus, Rizopus stolonifer, Trichoderma viride, Candida utilis, Geotrichum candidum and Saccharomyces cerevisiae. The pH and total titratable acidity (TTA) varied significantly during fermentation. The proximate composition of the raw blends, fermented, extruded and fermented- extruded samples were assessed. The crude protein and moisture content increased in the fermented, extruded and fermented- extruded samples; whereas fermentation and extrusion reduced the carbohydrate content. Fat, crude fibre and ash contents varied among all the samples. The sensory evaluation of the samples showed a good preference for fermented- extruded samples in terms of texture and aroma.