Vol. 6, Issue 10 (2017)

Author(s):
Syed Zameer Hussain, Bibi Afshana and Tawheed Amin

Abstract:
Walnut kernel supplementation increases the nutritional value of starch based expanded snacks. A systematic study was conducted for optimizing the blending level of broken walnut kernels and broken rice for the production of expanded snacks through co-rotating twin screw extruder. Response surface methodology was used to study the effects of feed composition, feed moisture, screw speed and barrel temperature on specific mechanical energy (SME), bulk density (BD), water absorption index (WAI), water solubility index (WSI), expansion ratio (ER), oil loss during extrusion, complexing index (CI) and breaking strength. Response surface regression models were established to determine the responses as functions of process variables. Regression models for all the responses were highly significant (p<0.01) with high co-efficient of determination (R²>0.83). The compromised optimum conditions obtained by numerical optimization for development of extruded snacks were broken walnut kernel flour to broken rice flour ratio (10:90), moisture content 14%, screw speed 550 rpm and die temperature 170 ⁰C.