PERFORMANCE EVALUATION AND PRODUCT CHARACTERIZATION OF A MAIZE FLOUR MILL

Abstract

The performance evaluation and product characterization of a maize flour mill that consist of electromechanical maize roaster and the hammer mill was conducted with the aim of achieving efficient roasting conditions and eliminating the drudgery associated with the roasting of maize. The machine was tested and evaluated in the Department of Agricultural Engineering, Federal University of Technology, Akure Nigeria using fresh maize (Swan-1-SR), sourced from Institute of Agricultural Research and Training, Obafemi Awolowo University, Moor Plantation, Ibadan, as sample for testing. The roasting efficiency of the machine was investigated at screw speed of 6.6 rpm, 11 rpm, 15 rpm, 19 rpm and 25 rpm; roaster temperature of 100⁰C, 125 ⁰C, 150⁰C, 175 ⁰C and 200⁰C; grain moisture content of 5.25%, 12% and 13% wet basis for the milling operation because other temperature and speed levels had been researched upon by (Akintade, A.M. 2012). A mass of sample size of 1kg was used for all the experiment. The result shows that the roasting efficiency increased as the temperature increased with the highest roasting efficiency of 94% recorded at the temperature of 100 0C, roaster speed of 19 rpm while the minimum roasting efficiency obtained was 45.87 % at temperature of 200 0C and machine speed of 6.6 rpm. The highest conveyance efficiency of 90.17% was recorded at the temperature of 150 0C, machine speed of 25 rpm while the minimum conveyance efficiency obtained was 50% at temperature of 125 0C and machine speed 6.6 rpm. The highest roasting capacity has maximum value of 11.62 kg/s at 100 0C with speed of 25 rpm while the lowest roasting capacity was obtained at 200 0C with speed 19 rpm. The machine throughput has maximum value of 11.3 kg/h at 1000C with machine roaster screw speed of 25 rpm while the minimum was 8.43 kg/h at 1000C with roaster screw speed of 6.6 rpm. The largest distributed grind maize in the 3.54 mm sieve was milled at 2000 rpm and at 5.25% moisture content. On the overall, Average Particle Size (APS) increased with increase in hammer mill speed with 1500 rpm having the lowest size and 2500 rpm having the biggest size. The average particle size with the finest grain was milled at 12% moisture content, 1500 rpm while the coarsest average particle size was milled at 12% moisture, 2500 rpm. The coarse particles of the maize were dominantly distributed with a total of 65 % over medium particles with 26 % and fine particle with 9 %, hence the total percentage uniformity index ratio for coarse, medium and fine particle was 5.4.3. For proper designation of agricultural material especially feeds we use both the FM and UI in the form 0.66:: 5.4.3