Investigation on mild extrusion cooking for development of snacks using rice and chickpea flour blends

A study was conducted to optimize the mild extrusion cooking conditions for development of rice and chickpea based extrudates. The independent variables i.e. extrusion parameters (Screw speed, barrel temperature), feed moisture and proportions of rice flour and chickpea flour were varied using central composite rotatable design (CCRD), and their effects on system parameter- Specific mechanical energy (SME) and product characteristics i.e., water absorption index (WAI), water solubility index (WSI), bulk density (BD), expansion ratio (ER), breaking strength (BS), colour values (L*, a* and b*) and overall acceptability (OA) were studied. All the system and product responses were significantly affected by independent variables. Response surface and regression models were established to determine the responses as function of process variables. Models obtained were highly significant with high coefficient of determination (R² ≥ 0.889). The optimum mild extrusion conditions obtained by numerical optimization for development of snacks were 102 °C barrel temperature, 281 rpm screw speed, 18.3% feed moisture and rice to chickpea flour ratio as 90:10. Storage studies confirmed that the developed snacks can be stored better in laminated pouches than in high density polyethylene (HDPE) bags for a period of 6 months under ambient conditions.