Using the Oil Press for Different Types of Oil Seed

Oil Press

There has been a lot of interest lately from existing oil press owners, concerning what is required to process different types of oil seed through their systems. The differences from one type of oil seed to the next have a direct effect on the operating parameters, which in turn effect how the seed is handled to and away from the system. It also requires changes in screw configuration for both the extruder and press and in some cases, the shim arrangement in the press cage. These changes are designed to optimize the efficiency of the oil press as it relates to oil recovery. The following will be a review of parameters, and differences from seed to seed.

Soybeans: Typically soybeans can range from 18% to as much as 21% oil content. Pre-extruded soy should be clean and less than 11% moisture. The soy should also be ground prior to extruding. Preferably the soy is rough ground or rolled into 4 or 5 pieces {no whole beans}. The soy can be fed to the extruder with an over the top, gravity type volumetric feeder. Post press handling includes grinding of the cake and cooling. If a rotary type cooler is used, the cake should be ground prior to cooling. If a counter flow type cooler is used, it’s best to grind after cooling. The screw configuration for both extruder and press are higher restriction.

Cottonseed: Typically 18% to 22 % oil. Moisture can vary widely, depending on harvest and storage conditions. Cottonseed is processed after ginning, and has some lint attached. This lint makes the seed bulky and presents some challenges in feeding it to the extruder. The seed should be as clean as possible, with any trash or dirt removed, as the fiber content of the seed makes it abrasive to begin with. In some cases the seed is extremely dry {7% or less}, and can require a small amount of water injection. The extruder and press configuration are the least restrictive of any of the express processes. The equipment feeding the extruder is not compatible with other oil seed processing. Post press handling is similar to soy; basically

Canola, Rape, Mustard and Flax type seeds: These seeds are what we consider high oil, typically 35% to as much as 50%, because of the high oil content, these types of seeds require a double pass to properly harvest as much oil as possible. This involves making a pass with the raw seed thru the press prior to extruding. Then following with a pass thru the extruder and the press. The high oil content means that the seed needs to be handled gently to avoid turning into an almost liquid or mushy state, which would cause plugging in the press. The pre-extruded pass is a question of metering the raw seed to the press and collecting the meal to be ran through the extruder and press on the second pass. The first pass requires some tightening of the choke. The screw configuration for the press and extruder are less restrictive than for soy. The vented chamber or inlet chamber on the press should be shimmed tighter to prevent the smaller seed from falling through the cage bars. The post extruded pass is similar to all the other processes as far as post grinding and cooling. The over the top volumetric feeder will work for the extruded pass on these products.

With all ExPress® systems, it is important to use a optimized vented conveyor system, specifically designed for customers designed by Insta-Pro to allow for removal of condensate or steam from the extruded product to avoid slippage in the press which reduces the amount of oil recovered.

Sunflower: In the case of sunflower seed, the seed must be processed with the hull on. Oil content for sunflower varies widely due to seed variety and geographical location. Oil contents will be from 32% to 45%. The process for sunflower is like the other high-oil content seed; as it is done in a double pass. The first pass not extruded, the second pass extruded and pressed.

If different seed is to be run on a consistent basis, one way to speed up the changeover would be to have an extra press shaft with the different screw configuration mounted on it, so you would just change out shafts instead of taking everything apart. The same can be done with the cage. An extra cage shimmed for the particular seed, is easier to switch than reshimming the whole cage.

The Insta-Pro press manuals that you receive with your equipment have illustrations of the different shaft and cage configurations for the different kinds of oil seeds. You can always contact Jim Little at, Ray Goodwin at  or me, John Doud, at if you have any questions.


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