Fermentation and Extrusion effects on Nutritional and Organoleptic Compositions of Unripe Plantain and Pigeon Pea Blends

Abstract

This research investigated effects of fermentation and extrusion on unripe plantain and pigeon pea blends. The samples were blended and prepared in three combinations (A=100g unripe plantain; B= 70g unripe plantain: 30g pigeon pea; C= 50g unripe plantain: 50g pigeon pea) and sectioned into four group (i.e. group 1 = preconditioned and fermented; group 2 = extruded; group three = fermented and extruded; and group 4 = unfermented/unextruded). Semi-solid state fermentation method was employed to ferment the blended samples for 96 hours. The physicochemical parameters (i.e pH, temperature and total titratable acidity) of these fermented samples were evaluated. The total microbial counts include; 9 bacteria, 2 yeasts and 4 molds were isolated and identified as; Bacillus subtilis, Bacillus cereus, Micrococcus luteus, Staphylococcus aureus, Lactobacillus plantarum, Lactobacillus fermentum, Leuconostoc mesenteroides, Lactobacillus mali, Streptococcus lactis, Saccharomyces cerevisiae, Candida utilis, Aspergillus niger, Aspergillus fumigatus, Aspergillus candidus, and Mucor hiemalis. There were significant variations in the values of pH and total titratable acidity (TTA) during fermentation. This was also same for the proximate contents of the fermented and extruded flour blends when contrasted with the raw flour blends. The fermented unextruded group 1 (11.73±0.01%) has the highest moisture contents and least in the raw sample B (6.34±0.00%). The raw flour blends protein content increased from 2.57±0.03 to 10.17±0.00% and from 2.58±0.02 to 16.27±0.01% in the fermented extruded blends. The carbohydrate content in the raw flour blends was highest (67.97±0.02 to 74.32±0.00%) and least in fermented unextruded samples (38.28±0.01 to 62.72±0.01%). The fat content was highest in the fermented unextruded blends (2.52±0.01 to 6.33±0.00%) and least in raw blends (1.33±0.02 to 2.01±0.02%). The sensory evaluation of the samples showed a good preference for fermented-extruded samples. Findings from this research have established that fermented and extruded unripe plantain and pigeon pea blend enhanced nutritional value of food.