Total seed oil and fatty acid methyl ester contents of Cuphea accessions

Abstract

Many Cuphea species have been identified as potential new sources 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 chromatographic analysis. Extraction and derivatization procedures were validated for linearity, precision, accuracy, and sample stability. Total oil content ranged from 10.1% in Cuphea llavea to 39.5% in Cuphea wrightii var. wrightii with a 2.5% relative standard deviation. C. llavea had the highest levels of capric acid at 92.0%. The highest levels of lauric acid were present in C. wrightii var. wrightii at 72.8%. Samples were stable for 24 h 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 chromatographic analysis produced reliable and reproducible results. 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.