|Dekeyser, Stephanie - U OF WI, MADISON, WI|
Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 20, 2006
Publication Date: May 1, 2006
Citation: Isbell, T., Green, L.A., Dekeyser, S.S., Manthey, L.K., Kenar, J.A., Cermak, S.C. 2006. Improvement in the gas chromatography resolution of petroselinate from oleate. Journal of the American Oil Chemists' Society. 83(5):429-434. Interpretive Summary: Coriander is a new crop that is under development for use of its novel oil composition. Often in the development of new crops large volumes of seed need to be chemically analyzed for new components. In the case of coriander, the unique fatty acid, petroselinic is found along with a very common fatty acid, oleic. Separation of oleic from petroselinic acid is very difficult but necessary to evaluate new improved plants from coriander. This manuscript describes a method to determine the amount of coriander and oleic acid simultaneously from this seed. Because of this method, breeders will be able to screen plants with higher levels of this unique fatty acid. Ultimately, production of coriander would lead to a new supply of raw materials that make nylons and detergents.
Technical Abstract: In the genus coriander, gas chromatography (GC) separations of petroselinate from oleate often gave poor resolution of these two isomers. Oleic and petroselinic acids were esterified with a series of alcohols (methanol, ethanol, 1-propanol, 2-propanol, 2-methyl-1-propanol, 1-butanol, 3-methyl-1-butanol and 2-ethyl-1-hexanol). GC resolution of the delta6 from the delta9 and delta11 octadecenoates was examined for all ester derivatives on a polar phase column. The delta6 and delta9 isomers were unresolved as methyl esters however, 2-ethyl-1-hexanol gave baseline separation of all three olefins under temperature programming conditions. When isothermal conditions were optimized for each ester, separation of these isomers was possible with good resolution values (> 89%) for all the alcohols except methanol which had a partial resolution of 51%. The rates of esterification of all the alcohols were determined for reactions with both oleic acid and triolein using potassium hydroxide as the esterification catalyst. Methanol gave the largest rate constant in both acid and oil esterification reactions with a rate constant 10-fold better than all of the other alcohols. Based on rates of reaction, resolution of petroselinate from oleate, and removal of residual alcohol, the ethyl ester derivative appears to be the best choice for seed oils containing petroselinic acid.