Submitted to: Association for the Advancement of Industrial Crops Conference
Publication Type: Abstract Only
Publication Acceptance Date: 9/20/2010
Publication Date: 9/20/2010
Citation: Evangelista, R.L., Isbell, T., Cermak, S.C. 2010. Extraction of Field Pennycress Seed Oil by Full Pressing [abstract]. Association for the Advancement of Industrial Crops Conference. p. 9.
Technical Abstract: Field pennycress (Thlasphi arvense L., Brassicaceae) is a winter annual that grows widely in the temperate North America. Its seeds contain up to 36% oil (db) with the major fatty acid as erucic acid (38%). With an estimated seed production of 1,700 – 2,200 kg/ha, pennycress can be a major source of oil for biodiesel. Also, the early harvest date of pennycress, compared to other winter annual oilseed crops, makes it suitable for a two-crop rotation with soybeans in most of the Midwestern United States. This allows for the production of oil for industrial application without displacing commodity crops for food use. The 2009 harvest of about 1,500 kg of pennycress seeds (32.9% oil, db) from a wild stand near Peoria, Illinois, provided our first opportunity to conduct oil extraction optimization studies. The goal of this study was to determine the optimum moisture content (MC) of pennycress seeds for oil extraction by full pressing. Two levels of starting seed moistures were employed: seed MC during storage (9.5%) and seed MC at harvest (16%). The latter was obtained by spraying the seed with a predetermined amount of water and allowing it to equilibrate for at least 24 h. Seeds (60 kg) with 9.5 and 16.0% initial MCs were cooked and dried (82-104 deg C) using a French Laboratory Seed Cooker/Conditioner (Model 324). The residence times were varied to produce cooked seeds with MCs ranging from 1.0 to 13.0%. The cooked seeds were pressed immediately using a heavy duty French Laboratory Screw Press (Model L250). Uncooked seeds with 9.5% MC were also cold-pressed to serve as a control. The residual oil in the press cake was determined and the amounts of oil extracted were calculated. The oils were also analyzed for solids content (foots), free fatty acid (FFA) content and color. Cold-pressing pennycress seeds with 9.5% MC produced press cake with 10.7% oil (db), extracting 75.1% of the oil. Cooking and drying the seeds to 4% MC provided the lowest residual oil at 6.2%, or 86.3% of the oil recovered. There was a slight improvement in the amount of oil extracted (88.0%) when the starting seed moisture was at 16% and then cooked and dried to 4%. Compared to the oil from cold-pressed seeds, the oils from cooked seeds had higher foots (1.55-1.73% vs. 0.52%), FFA contents (0.40-0.46% vs. 0.30%) and red values in the American Oil Chemists' Society RY color scale (4.1R - 6.2 R vs. 2.4R). These results showed that tempering pennycress seeds to higher moisture is unnecessary for maximizing oil recovery. In addition, cooking and drying the pennycress seeds to 4% MC before pressing had minimal effect on the oil’s quality with respect to FFA content and color.