Method for analysis of fatty acid distribution and oil content on a single Lesquerella fendleri seed
2008
Isbell, Terry A. | Mund, Melissa S. | Evangelista, Roque L. | Dierig, David A.
Lesquerella fendleri is a developing oilseed crop suitable for temperate growing regions in the US. The seed oil is rich in lesquerolic acid (57%) and could serve as a domestic source of hydroxy fatty acids. A method for the analysis of fatty acids and total oil content of a half or single lesquerella seed was developed. Lesquerella seeds are small with 1000 seed weights around 0.6g (half seed mass of 200-500μg). Conventional analytical balances provide mass accuracy to ±40μg which fails to provide sufficient accuracy/precession (4-40% mass error) for the initial seed mass. A microbalance which measures to ±2μg provided good reproducibility in initial seed weights but was not suitable for mass balance of the extracted oil. A normal phase HPLC coupled to an evaporative light scattering detector gave good response for oil in the mass range of 22μg to 110μg/mL. Therefore, micelle concentrations from single or half seed extractions could be determined with good reproducibility. This method was then evaluated on bulk seed that had been fractionated on a gravity table. Gravity table fractionation of L. fendleri seeds obtained from a large field plot provided seven fractions with increasing bulk density. These fractions were then analyzed in sets of 30 individual seeds and as an aggregate of 50 seeds. Oil content for individual seeds varied widely (15.6-44.2%) as did lesquerolic acid content (42.2-63.7%). The mean oil content increased (27-33%) with increasing bulk density (684-745g/L). The mean lesquerolic acid content did not correlate with bulk density.
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