Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2006
Publication Date: 7/17/2006
Citation: Phippen, W.B., Isbell, T., Phippen, M.E. 2006. Total seed oil and fatty acid methyl ester contents of cuphea accessions. Industrial Crops and Products. 24(1):52-59. Interpretive Summary: Cuphea is a new crop currently being developed in the U.S. to produce a novel vegetable oil that will be used in the soap and detergent industry. Critical to the development of cuphea is the successful breeding and selection of plants that have characteristics suitable for planting, cultivation and harvesting in addition to the correct chemical profile (fatty acids) in the seed oil. A method to analyze the fatty acids that is both rapid and leaves half the seed for propagation was developed. This new method is both rapid and accurate. This method provides breeders with faster selections for improved cuphea lines.
Technical Abstract: Cuphea species have been identified as a potential new source of unique fatty acids for both the lubricant and soap and detergent industries. Current breeding programs have focused on improving agronomic traits to make cuphea suitable for commercial production. Breeding programs are now focusing on altering total oil and fatty acid content with a special interest in lauric and capric acids. Accessions identified as high in oil content and rich in single fatty acids will be introgressed into the current agronomically sound breeding lines. The objective of this study was to develop a reliable and efficient method for evaluating cuphea accessions for their total oil and fatty acid content in cuphea seed. One hundred and eighty-five accessions of cuphea were screened for their total oil and fatty acid content. Total oil content was determined by nondestructive pulsed NMR on whole cuphea seed. Previous extraction and derivatization procedures were combined and optimized to minimize time and complexity in extracting medium-chain triglycerides and derivatizing them into fatty acid methyl esters for gas chromatography analysis. The new gas chromatography analysis, extraction, and derivatization procedures were validated for linearity, precision, accuracy, and sample stability. Total oil content identified by pulsed NMR ranged from 10.1% in Cuphea llavea to 39.5% in Cuphea wrightii var. wrightii. Pulsed NMR results had a 2.5% relative standard deviation. Gas chromatography was used to determine the fatty acid methyl ester content. Cuphea llavea contained the highest levels of capric acid at 92.0%. The highest levels of lauric acid were found in Cuphea wrightii var. wrightii at 72.8%. Results were within the demonstrated linear range of the analysis with a 99.9% confidence level from the linearity studies. Samples were found to be stable for a 24 hour period at room temperature. Recoveries for methyl caprate and methyl laurate were 98%. Relative standard deviations for methyl caprate and methyl laurate were 2.9% and 6.1% respectively. Validation results demonstrated that the extraction, derivatization, and gas chromatography analysis produced reliable and reproducible results. The protocol developed for this study can aid breeders to accurately determine total seed oil and fatty acid content for various cuphea species. The cuphea species identified in this study can serve as potential new sources for high seed oil content and fatty acids to be introduced into the current advanced breeding lines.