Effects of Extrusion-Cooking on the Nutrient and Anti-Nutrient Composition of Pigeon Pea and Unripe Plantain Blends

The effects of extrusion cooking on the nutrient and anti-nutrient composition of raw and extruded blends of pigeon pea and unripe plantain flours were evaluated. Pigeon pea seeds were cleaned and processed into flour while unripe plantain was peeled, sliced, dried and milled into flour separately and sieved to pass 0.85mm mesh. The moisture content of the flours was determined. Unripe plantain flour was added to pigeon pea flour at 25% levels of substitution. The moisture content of the blends was adjusted to 25% levels. The blends were extruded using a Brabender laboratory single-screw extruder (Duisburg DCE 330 model) at 120rpm and temperature of 1000c. The proximate composition, minerals, amino acid profile and some vitamins of raw and extruded samples were determined. Antinutrients (Phytate, saponnis, oxalate, tannin, trypsin inhibitor, lectin and hydrogen cyanide content) of raw and extruded samples were also estimated. Results of proximate composition, showed a significant (P<0.05) increase in fat content (1.97%) and energy value (1420 kj/100g), while marginal decrease was noticed in protein (22.98%), ash (3.72%) and crude fibre (7.04%). The results of mineral content showed significant (p<0.0.5) increase in the extrudate iron (5.02mg/100g) zinc (4.35mg/100g) calcium (32.35mg/100g) and potassium (333.07mg/100g). Vitamin content was significantly (P<0.05) reduced in the extrudate Vitamin A (4.29mg/100g), Vitamin B1 (4.03mg/100g), Vitamin B2 (0.40mg/100g), and Vitamin C (0.01mg/100g). The amino acid profile was affected by extrusion process but the essential amino acids in the extrudate met requirements for adults. Blending pigeon pea and unripe plantain flour at 25% of unripe plantain flour substitution resulted in the reduction of anti-nutrients evaluated. Extrusion cooking further considerably lowered these anti-nutrients to safer levels.