ABSTRACT

 This study involves development and multi objective analysis of an integrated milling and sieving machine for Bambara flour production. This will improve hygiene and reduce excessive drudgery and food loss in this sector thereby aiding mass production of quality bambara flour at low cost. Its major components include: electric motor, flour and chaff discharging chutes, turbo-pneumatic sieve and hammer mill. Performance of this machine was empirically evaluated and quantified using response surface design and models at two levels of factors while desirability optimization and benefit cost methodologies constitute the optimization and investment analysis techniques applied in this investigation. Performance analysis results revealed Bambara grains’ moisture content, number and speed of cross beaters and paddles as these machine process/operational parameters (factors) with significant influence on its performance while throughput and extraction efficiency constitutes its functional performance indicators (responses). The cross beater and grains’ moisture content affect the particle size of the milled grain directly while sieving (extraction) of the grain food/starch granules (flour) from its fiber (chaff) depends on this particle size and paddle parameters. In addition, the multi-response performance simulation of this machine predicted 12.05%, 6, 4, 1610rpm and 1038rpm as the grain moisture content, number of cross beaters and paddles, cross beater and paddle speeds require for its optimal operation with over 98% accuracy. The machine performs with throughput and extraction efficiency of 117.8kg/h and 98.45% respectively at these optimal factor settings. Experimental evaluation revealed 41.15kg/h and 84.18% as the average throughput and extraction efficiency of semi-mechanized Bambara flour processing system. Thus, the novel Bambara nut milling-sieving machine for Bambara flour production reduced the food loss to chaff in this sector to 1.55% against 15.82% associated with the widely used semi-mechanized system. It also promotes hygiene in this sector because it eliminated human contact with the milled grain during sieving. The cost-benefit analysis of this machine showed that it is viable economically because of its positive capital recovery potentials. The machine’s payback period of 1.5years is far less than its useful life of 10years, while its 46.89% accounting rate of return outweighed Nigerian banks maximum fixed deposits return of 17% and prime lending rate of 29%. Therefore, general adoption of the integrated milling and sieving machine developed in this study is recommended for Bambara flour processing.