Location: Bio-oils Research Unit
Title: Extraction of pennycress (Thlaspi arvense L.) seed oil by full pressing Authors
Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 5, 2011
Publication Date: May 1, 2012
Citation: Evangelista, R.L., Isbell, T., Cermak, S.C. 2012. Extraction of pennycress (Thlaspi arvense L.) seed oil by full pressing. Industrial Crops and Products. 37(1):76-81. Interpretive Summary: This study established the first guideline in extracting oil from pennycress seeds by screw pressing. The screw press will be widely used during the early stages of pennycress commercialization when oil extraction facilities are still operating below 100 MT/day. Pennycress seed oil can be successfully extracted using a screw press with little seed preparation. Seed cooking had little effect on the acidity and color of the expelled oil. Also, seed cooking increased the gums content but the amount was still comparable to degummed oils. However, the sulfur levels in the expelled oil could be considerably higher than the amounts found in other expelled mustard seed oils depending on the extent of cooking employed. Best oil quality was obtained when seed heat treatment was kept to a minimum.
Technical Abstract: Pennycress is currently being developed as an oilseed crop for biofuel production. Pennycress seeds harvested from a field near Peoria, IL, provided our first opportunity to conduct an oil extraction study on a pilot scale. The goals of this study were to determine the effects of seed moisture and cooking on the pressing characteristics of pennycress seeds and to evaluate the quality of the oils extracted. Pennycress seeds (60 kg) with 9.5 and 16% moisture contents (MC) were cooked and dried (82-104 deg C) using a steam-heated 3-deck laboratory seed cooker. 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 laboratory screw press. Pressing rate, press load, and residual oil in the press cakes were determined. The oils extracted were analyzed for solids content (foots), free fatty acid (FFA) content, color, and phosphorus (P), calcium (Ca), magnesium (Mg), and sulfur (S) contents. Pressing uncooked pennycress seeds with 9.5% MC produced press cake with 10.7% oil (db), extracting 75.1% of the oil in the seed. Cooking and drying the seeds between 3 and 4% MC provided the highest oil recovery at 86.3 and 88.0% for seeds with 9.5 and 16% starting seed MC, respectively. The pressing rates and press loads at these MCs were similar. Compared to the oil from uncooked seeds, the oils from cooked seeds had higher foots (1.55 to 1.73% vs. 0.52%), slightly higher FFA contents (0.40 to 0.46% vs. 0.30%), and slightly higher red values in AOCS RY color scale (4.1R to 6.2 R vs. 2.4 R). Cooking increased the phosphatide content but the amount was still comparable to degummed oils. The sulfur levels in the expelled oil were higher than the amounts found in rapeseed oil and varied considerably depending on the seed moisture and the extent of cooking employed.