Optimisation of Rice-Kidney Beans Composite Flours Incorporated with Fermented and Unfermented Sorghum Flours for the Production of Ready-to-Eat Extruded Snacks

Abstract

Aims: Rice-based ready-to-eat extruded snack was developed by incorporating the rice flour with kidney bean, fermented surgum and unfermented sorghum flours with the sole aim of accessing the effect of the addition of the kidney bean and sorghum on the nutritional quality of the extruded snack developed. Methodology: Rice-dried kidney bean composite flours were supplemented with fermented and unfermented sorghum grains were optimized using optimal design model of response surface methodology; the dependent variables were the proximate and mineral compositions. The extrusion process was also optimized using central composite design of response surface methodology. The sensory evaluations of the extrudates were carried out. Results: The result of the product optimization of the composite flours gave the R-squared and adjusted R-squared of the ash, crude fibre and crude protein to be between 0.9961 and 0.9987. R-squared and adjusted R-squared close to unity is an indicated of statistical model that is fit, and hence, show that the independent variables support the dependent variables strongly. So, we can deduce that the independent variables strongly supported the ash, crude fibre and crude protein contents. The extrusion results showed that screw speed was the most potent factor required for the extrusion process, followed by temperature. Sample 19 having independent variables of 21.7% screw speed, 80oC temperature and 105 rpm resulted in extruded snack with the highest overall sensory acceptability. Conclusion: Acceptable snacks with over 70% sensory qualities were developed. Addition of fermented sorghum flour resulted in composite flour with protein content were well above 100%.