Development of a motorized hydraulic press for sesame (Sesamum indicum L.) oil expression

Abstract

Sesame oil is edible and of high economic and medicinal potentials. However, its expression from the seeds is still largely done manually which is tedious and inefficient. The few imported mechanical oil presses are prone to incessant breakdown and costly. A motorized hydraulic press for sesame oil expression was designed, fabricated and tested. The major components of the machine include a hydraulic cylinder, hydraulic pump, two-way control valves, heater band with temperature controller, stopper plate, electric motor and the frame. Paste of ground sesame seeds wrapped in a cheese cloth was forced against a stopper end plate on the expression barrel whose temperature is controlled in order to get the oil expressed out. The machine performance was evaluated using two levels of seed conditions (roasted (RS) and unroasted (URS)) at three levels of moisture contents (6, 9 and 12% wet basis) and four levels of temperature (70, 80, 90 and 100ºC). The performance indicators investigated included: throughput capacity, percentage oil yield, percentage expression efficiency and cake recovery efficiency. Results of tests showed that the highest percentage oil yield of 33.3% was recorded when sesame seed was roasted, milled and pressed at a moisture content of 6% and expression temperature of 90ºC. Also the highest expression efficiency was recorded as 69.4% when the seed was roasted, milled and pressed at a moisture content of 6% and temperature of 90ºC. The highest cake recovery was recorded as 74% when the sesame seed was milled without roasting at a moisture content of 12% and temperature of 70ºC. The oil press would assist in the growth of indigenous edible oil production industry.