Milling of Cowpea Flour Using Cyclone Assisted Milling

Abstract

A two-part factorial design was used to evaluate the effects of mill configuration and operational parameters of a cyclone assisted impact/attrition mill, and preconditioning treatments of cowpea seed on the geometric mean particle diameter (dgw) and yield of cowpea flour. Cowpea flour was milled using a Super Wing Mill DM-200 cyclone assisted impact/attrition food mill. Milling parameters (mill configuration, turbine speed, airflow restriction, sample feed, and milling time) and sample preconditioning treatments (moisture and temperature) were systematically altered to examine the dynamic response on the dgw and yield of cowpea flour. A two-part factorial design (25 and 33) showed that the modified wing mill configuration produced a larger dgw along with a significant increase in yield; turbine speed and airflow restriction within the mill offered additional control of dgw and yield. Preconditioning of cowpea seed showed that temperature preconditioning had no effect on the dgw or yield, but preconditioning of moisture content had a significant effect on dgw and yield of cowpea flour. Parameters for the milling of fine cowpea flour (dgw = 17m; = 90% yield) were identified as using preconditioned cowpea seed at 4% moisture (20C) milled using the modified wing mill configuration with a turbine speed of 7200 rpm at a 90 airflow restriction for 5 min of milling time.