Location: Bio-oils Research Unit
Title: Isolation and enrichment of the erucic acid from Thlaspi Arvense (Pennycress) oil 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: Isbell, T., Evangelista, R.L., Rao, S. 2012. Isolation and enrichment of the erucic acid from Thlaspi Arvense (Pennycress) oil [abstract]. Association for the Advancement of Industrial Crops Conference. p. 13. Technical Abstract: Pennycress is being developed as an off-season rotation crop between annual corn and soybean production. This rotation scheme may offer distinct advantages to farmers by providing additional farm income from an otherwise fallow season with little impact on the subsequent soybean production. The seed contains up to 36% oil with the major fatty acid as erucic (36.6%). The fatty acid composition in thlaspi has been shown to have physical properties suitable for biofuels like biodiesel and hydro-treated renewable jet fuel (HRJ). Like many developing new crops, the chemical characterization and methods for enrichment of the individual components of the triglyceride have yet to be reported. Of particular interest is the isolation and enrichment of erucic acid, which has a number of potential industrial applications. The triglyceride composition of pennycress oil was determined by HPLC using a C8 column which separated the individual triacylglycerides into 9 individual triglyceride groups of carbon chain lengths that ranged from 48 to 64. Each individual peak was isolated on a HPLC by 25 repeated 100 uL injections of a 20 mg/mL solution of pennycress oil dissolved in acetone, followed by elution using a gradient of acetonitrile/acetone from 50:50 to 0:100 over 20 min then collecting at 0.2 min/fraction. Pure individual peaks were obtained and concentrated from the fraction collector and subsequently analyzed by GC as their methyl esters and the whole triglycerides analyzed by NMR. In addition, known standards were injected on the HPLC to confirm retention time assignments for eluted peaks. Enrichment of erucic acid was accomplished by three independent methods on fatty acid methyl esters and potassium soaps from pennycress oil. Molecular distillation of the methyl esters at 90 deg C under 50 mTorr of pressure enriched the erucic acid content from 36.6% to 64.6% in a single pass with the erucic fraction consisting of 76% of the mass balance. A second pass distillation of the enriched erucic fraction increased the 22:1 content to 70.7% with the second pass mass balance of 60% and an overall mass balance of the erucic fraction of 42.2%. Molecular distillation of the fatty acids provided a less effective enrichment, only providing a 52.5% erucic acid fraction in a 68.9% overall mass balance in a two pass distillation. Fractionation by crystallization of the potassium soap during hydrolysis of the triglyceride provided the largest enrichment of the erucic acid. When the potassium erucate was allowed to crystallize from the mixture of pennycress soaps in a 90:10 methanol water solution (5:1 volume/mass solvent to soap) gave a 66% erucic acid fraction that was 71% of the theoretical erucic acid content. Higher purity erucic acid (87%) could be obtained when ethanol water was used as a crystallization solvent but theoretical erucic acid mass recovery was low (23%).