EFFECTS OF FERMENTATION AND EXTRUSION ON THE NUTRIENT AND ANTINUTRIENT COMPOSITION OF RIPE PLANTAIN AND GROUNDNUT BLEND

Abstract

This study was designed to monitor the effect of fermentation and extrusion on ripe plantain and groundnut blends. The blended samples were prepared in five combinations (A=100% ripe plantain; B= 80% ripe plantain: 20% groundnut; C= 60% ripe plantain: 40% groundnut; D= 50% ripe plantain: 50% groundnut and E= 100% groundnut) and separated into four batches (i.e. first batch, preconditioned and extruded; second batch, fermented; third batch, fermented and extruded; and fourth batch, unfermented/unextruded). The fermented samples were fermented for 96 hours in submerged state fermentation. The pH, temperature and total titratable acidity (TTA) of the fermented samples were determined (AOAC, 2015). The nutrient and antinutrient content, in-vitro protein and starch digestibility as well as sensory properties of the blended samples were determined using standard methods. A total of fourteen microorganisms comprising /9/ bacteria, /3/ molds and one /1/ yeast were isolated. The isolated microorganisms were Bacillus subtilis, B. cereus, B. polymyxa, Proteus mirabilis, Staphylococcus aureus, S. epidemidis, Lactobacillus plantarum, L. fermentum, Pseudomonas aeruginosa, P. flourescens, Aspergillus niger, A. flavus, Fusarium oxysporum and Saccharomyces cerevisiae. The pH and TTA values varied significantly (3.76 to 6.90) and (0.009 to 0.042) with fermentation time. The temperature reduced significantly as the fermentation day increases. The fermented sample showed increase in moisture and crude fibre contents (32.6 and 17.5 respectively) in samples E and B while raw blend B and D had lowest values (2.19 and 0.66 respectively) when compared to the extruded samples. The carbohydrate and protein contents recorded the highest value (80.8 and 16.6 respectively) in Extruded fermented plantain 100% and extruded unfermented groundnut 100%. Sodium and potassium recorded highest values in the fermented samples while magnesium and calcium recorded highest values (120 and 220 respectively) in extruded fermented plantain 100%. The anti-nutrient content of fermented and extruded blends decreased significantly (p≤0.05) when compared to the raw samples. The sensory parameters of the fermented and extruded samples were relatively accepted. Findings from this study showed that ripe plantain and groundnut blend can be fermented and extruded to produce food of enhanced nutritional value containing low anti-nutrient content