EFFECT OF WHEAT GERM PRETREATMENT ON OIL EXTRACTION BY EXPELLING MACHINE

Abstract

An atmospheric steam process is used for preheating (in the range of 60-70°C) and increasing the moisture content (m.c.) of the wheat germ to study the effect of such process on machine capacity, percentage of oil recovery, percentage of residual oil, and specific energy consumption (SEC)of a double stage expelling machine for wheat germ oil extraction. Four levels of m.c. (13.2, 15.4, 16.2, and 16.8%), and five screw rotation speeds (25, 35, 45, 55, and 65 rpm) were used. It was found that at 25 rpm of screw speed, increasing m.c. from 13.2% (initial m.c.) to 16.2% (wb.), increased the machine capacity by 23.7%, and increased SEC from 0.043 to 0.482kWhkg-1feed(including the energy consumption needed for steam generation). At 16.2% m.c. and 65rpm screw speed, the percentage of oil recovery and oil productivity were 53.42% and 1.97 litter/h, respectively. The maximum percentage of oil recovery (62%) was obtained at 16.2% m.c. and 25rpm screw speed. The economic feasibility data indicated that the total hourly cost was about 11.80EGP/h, and the total cost of oil extraction was about 49.48 EGP/litter of oil. A net annual profit of 160941.3 EGP can be earned providing a Benefit-Cost-Ratio of 1.07, a Return on Investment (ROI) of 106.5% with a Pay-Back Period of 0.07 yr. In addition, the unit would generate an employment of 480 man-days at rural level.