The process of pressing oil from a crop is in principal straight forward, and the result is a healthy and natural product, after all we are simply squeezing out the oil, no chemicals or high temperatures are involved. However most of the raw materials we press are harvested from natural products and with the variability inherent in soil type, weather, crop variety, harvesting conditions and drying methods you need a press that is flexible enough to accommodate these variations. The operator too must be flexible enough to learn and become a skilled oil pressing expert.

  1. The raw material must be clean and within the optimum window of moisture content, not too dry not too wet. Information about preparing the seed is available.
  2. We now need to get the seed to the press. Gravity feeding from a hopper above or using a screw conveyor/auger to feed the press from a bin or silo are the most usual methods.
  3. Pressing. Seed in the press hopper flows into the press chamber where pressure is increased (sometimes, this involves regions where the pressure is reduced or held steady, the flow is interrupted, slowed or sped-up, mixing areas etc.) this causes the oil cells to release their oil and separate from the solids called meal or cake. With mechanical pressing there is always some fine seed pulp within the ‘crude’ oil and although it is not possible to get every drop of oil out from the meal it is important to de-oil it as much as possible especially if the meal is to be milled into flour/powder a high protein content is desired. The better the press, and the better it is configured for a particular crop, the better is the separation.
  4. Oil flows from the press into a tank. In small-scale batch type production the oil is sometimes allowed to settle in one or more tanks for several days, most of the solids fall to the bottom of the tank and then the oil above the sediment is pumped through a polishing filter to strain out the remaining fine particles. In larger operations the oil from the press falls into a tank with a slowly rotating paddle, this gentle stirring keeps all of the solids in suspension and the oil can then be pumped through a special filter without needing to settle. This allows for continuous filtration and if desired 24/7 pressing and filtering. The oil from the filter is clear and bright, this is the pure natural oil ready to be bottled.
  5. Meal from the press is often valued for its high protein. Sometimes it is used as an animal feed supplement and sometimes it is used as a human food ingredient. Vegetable protein is a valuable food and can sometimes be more valuable than the oil, which becomes the secondary product. Meal that is pressed in a high quality oil press is de-oiled enough to be milled into a flour and further processing can remove some of the fiber thereby increasing the protein content further to make protein flours and powders.

We can provide a wide range of equipment for, and advice about, seed conditioning, pressing, filtration, bottling and meal processing. If you have a question please get in touch.