The Basic Theory and Process of Oil Extraction by Pressing-Oil Mill Plant

When people talk about pressing express, they usually refer to hydraulic press and screw press, continuous screw pressing machine is vastly used in the pressing progress. The processes might be slightly different but the theories are the same: use mechanical force to press and extract the oil out of the flake. Physical changes happen in the pressing process: oilseeds’ deformation; grease separation; friction and heat; moisture evaporation. Temperature and moisture changes, microorganism in the oilseeds and other similar factors cause chemical changes like passivation and destruction of enzyme, protein denaturation, etc. 

In the pressing section, the structure of oilseeds is high degree-squeezed and oilseeds becoming a hard cake while the oil is extracted. The surface of the cake barely contains any oil anymore, but there is still some oil remained in the cake as there are blocked oil path in the cake. Low oil viscosity, short oil path, high pressure are the three factors that influence the speed of oil extraction, so the oilseed quality and technique is very important.