Effect of extrusion parameters on physical and functional quality of soy protein enriched maize based extruded snack

Abstract

The effect of extrusion parameters like barrel temperature (100-150°C), screw speed (110-350 rpm) and feed moisture content (12-20% wb) on product quality of extruded products prepared from composite mixture was performed. Central composite rotatable design was used to frame the experiment and statistically analyzed the data. The effect of parameters on expansion ratio (ER), bulk density (BD), hardness (H), crispness (Cr), water absorption index (WAI) and water solubility index (WSI) of extruded products were investigated and found significantly. The feed moisture had positive effect on BD, hardness and WAI whereas negative effect on ER, crispness and WSI of the extruded products. The barrel temperature and screw speed had negative effect on BD, hardness and WAI whereas reverse effect on ER, crispness and WSI. The developed models for all the product qualities were significant at 1% level. ER, BD, hardness, crispness, WAI and WSI values of extruded products was ranged from 2.017–3.391, 0.13–0.28 g/cm3, 12.43–19.04 N, 10–25 fractures, 5.76–7.25 g/g and 12.76–20.97%, respectively. The higher expansion ratio, crispness and WAI along with lower bulk density, hardness and WSI of extruded product were found at the process parameters combination of feed moisture 14% (wb), barrel temperature 110°C and screw speed 301 rpm.