Chayote-finger millet enriched extruded RTE snacks: Quality evaluation and process optimization

The present study aims to develop extruded ready-to-eat (RTE) snacks using underutilized finger millet flour, chayote pulp and corn flour with the help of co-rotating twin screw extruder. The effect of process parameters like barrel temperature (110 °C, 120 °C and 130 °C), screw speed (250, 275 and 300 rpm), feed moisture content (18%, 20% and 22% wet basis) and millet flour percent (20%, 25% and 30%) on physical properties (bulk density, expansion ratio, hardness), functional properties (water absorption index, water solubility index and oil absorption capacity) and sensory evaluation were analyzed and optimized using desirability function based numerical optimization. The desired extrudate found at optimum barrel temperature of 120 °C, screw speed of 284 rpm, feed moisture content of 22% wb and millet flour percent of 20% showed bulk density of 0.149 g/cm³, expansion ratio of 1.94, water absorption index of 7.73 g/g, water solubility index of 6.164/100 g and oil absorption capacity of 2.46/100 g. All process parameters were significant at p < 0.05. Extrudates contain about 73.3% more protein, 38.5% more fibre and 33% less fat compared to pure corn extrudates. The optimized blend composition for development of best quality chayote – finger millet enriched extruded RTE snack was at millet flour: 20%, chayote pulp: 10% and corn flour: 70%. Overall acceptability of the optimized extruded snacks was 7.87 as observed form sensory evaluation. The findings of the study may be helpful for developing healthier and more nutrient-rich snacks using millet and chayote.