Advantages and disadvantages of the expeller process;
Expellers can be used with almost any kind of oilseeds and nuts. The process is relatively simple and not capital-intensive. While the smallest solvent extraction plant would have a processing capacity of 100-200 tons per day, expellers are available for much smaller capacities, from a few tons per day and up.
The main disadvantage of the screw-press process is its relatively low yield of oil recovery. Even the most powerful presses cannot reduce the level of residual oil in the press-cake below 3 to 5%. In the case of oil-rich seeds such as sesame or peanuts this may still be acceptable. Furthermore, most of the oil left in the cake can be recovered by a stage of solvent extraction. Such two stage processes (pre-press/solvent extraction) are now widely applied . In the case of soybeans, however, a 5% residual oil level in the cake represents an oil loss of about 25%. Solvent extraction of the cake would not be economical, because of the bulk of material which must be processed.