Location: Bio-oils Research Unit
Title: Extraction of oil from Euphorbia Lagascae seeds by screw pressing Authors
Submitted to: Association for the Advancement of Industrial Crops Conference
Publication Type: Abstract Only
Publication Acceptance Date: November 12, 2012
Publication Date: November 12, 2012
Citation: Evangelista, R.L., Isbell, T., Roseberg, R.J., Cermak, S.C. 2012. Extraction of oil from Euphorbia Lagascae seeds by screw pressing [abstract]. Association for the Advancement of Industrial Crops Conference. p. 54. Technical Abstract: Euphorbia lagascae (Spreng.) is a drought tolerant plant native to Spain. Euphorbia seeds contain 45-50% oil with 60-65% of its fatty acids as vernolic (12S,13R-epoxy-cis-9-octadecenoic) acid. Vernolic acid has wide applications in paints and coatings, plasticizers, adhesives, polymers, and lubricants. Current sources of epoxy fatty acids include epoxidized soybean oil and processed petrochemicals. The seed also contains hydrolytic and hydrating enzymes which become active when seeds are crushed, resulting in changes in free fatty acid (FFA) content, iodine value, and epoxy content in the oil. High temperature treatment or seed conditioning is necessary to inactivate these enzymes. Although conventional seed processing routes, such as hydraulic pressing, mechanical expelling, and solvent extraction, have been explored to extract oil from euphorbia, information on these studies are very limited. The goal of this study was to determine the optimum cooking temperature and moisture content (MC) of euphorbia seeds for oil extraction by screw pressing. The seeds were obtained from field trials conducted at Klamath Basin Research & Extension Center, Klamath Falls, Oregon. The seeds (2.5 kg), with 5% (as stored) and 10% MC, were heated to 37.8, 60.0, 82.2, and 104.4 oC and held at these temperatures for 20 min using a fluidized bed dryer (Endecotts FBD2000). The dryer was preheated to 148 oC before use. The heated seeds were screw-pressed immediately using a tubular radial expeller (Scott Tech ERT60II). The oil in the seed and the residual oil in the press cakes were determined and the oil yields were calculated. The oils were also analyzed for solids and FFA content. The bulk euphorbia seeds contained 41.1% (dry basis, db) oil. Clean seeds (after removing seeds incased in shell) had an oil content of 46.1% (db). The highest oil yield (66%) was obtained from seeds with 10% MC and heated to 82.2 or 104.4 oC. The amount of solids in the oil ranged from 13.6 to 55.5%. The amounts of solids in the oil were lower when the MCs of the heated seeds were between 3 and 5%. Oil from unheated seeds had the highest FFA (10%). The amount of FFA decreased with increasing the heating temperature but leveled off around 6.1 to 6.6%. Also, heated seeds with MC below 4% tend to have lower amounts of FFA. Therefore, the optimum conditions for screw pressing euphorbia seeds include tempering the seeds to about 10% and cooking the seeds from 82 to 104 oC and keeping the final MC between 3-5%. We anticipate that double pressing the seeds will improve the oil yield to >90% as the residual oil in the press cake goes down to about 5% as one would expect in a commercial-scale pressing operation.