Fermentation and Exrusion Effects on the In Vitro Proteinand Starch Digestibility of Unripe Plantain and Pigeon Pea Blends

Abstract

This study investigated effects of fermentation and extrusion on the in vitro protein andstarch digestibility of unripe plantain and pigeon pea blends. The blended samples were set-up in three arrangements (A=100g unripe plantain; B= 70g unripe plantain: 30g pigeon pea; C= 50g unripe plantain: 50g pigeon pea) and divided into four batches (i.e. first batch = preconditioned and fermented; second batch = extruded; third batch = fermented and extruded; and fourth batch = unfermented/unextruded). Semi-solid state method of fermentation was deployed to ferment blended samples for 96 hours. The pH, temperature and total titratable acidity (TTA) of these samples were evaluated. Fifteen microorganisms comprising 9 bacteria, 2 yeasts and 4 molds were isolated and identified as; Bacillus subtilis, Bacillus cereus, Micrococcus luteus, Staphylococcus aureus, Lactobacillus plantarum, Lactobacillus fermentum, Leuconostocmesenteroides, Lactobacillus mali, Streptococcus lactis, Saccharomyces cerevisiae, Candida utilis, Aspergillusniger, Aspergillusfumigatus, Aspergilluscandidus, and Mucorhiemalis. There were notable variation in the values of pH and total titratable acidity (TTA) during fermentation. The processes of fermentation and extrusion significantly amplified the in vitro starch digestibility of the flour blends with fermented extruded samples (51.03±0.02 to 55.19±0.02mg/ml) unlike theraw flour blends (36.77±0.20 to 41.26±0.003mg/ml).The in vitro protein digestibility significantly increased with the extruded fermented samples (12.73±0.17 to 15.45±0.06mg/ml) and lowest forraw flour blends (4.57±0.29 to 5.98±0.37mg/ml). Hence, it can be concluded based from the available information from this study that fermentation and extrusion increase the in vitro starch digestibility and protein digestibility of unripe plantain and pigeon pea blends.