Fuel properties of methyl esters of borage and black currant oils containing methyl γ-linolenate

In this work, the methyl esters of two oils enriched in -linolenic acid (6Z,9Z,12Z-octadecatrienoic acid) were prepared under the aspect of evaluating their properties, including potential fuel properties. One oil is black currant oil in which -linolenic and -linolenic (9Z,12Z,15Z-octadecatrienoic acid) are relatively evenly distributed, and the other oil is borage oil which mainly contains -linolenic acid as C18:3 species. The fatty acid profiles of both oils confirm literature results. The cetane number (CN) of neat methyl -linolenate was also determined for the first time as 29.2, which is slightly higher than that of the more common methyl -linolenate. The methyl esters (biodiesel) from such oils meet most property specifications in biodiesel standards with the exception of feedstock restrictions on highly unsaturated fatty acid chains, although CNs are lower and antioxidants are required for oxidation stability. Although, due to their nutritional value and limited occurrence, these oils are unlikely biodiesel feedstocks themselves, their methyl esters may be seen as models for similar derivatives from other feedstocks with elevated levels of unsaturation, including algal oils. The H-1 and C-13 NMR spectra of black currant and borage methyl esters are also reported.