Fatty acid composition of Tilia spp. seed oils

As part of a study of the seed oil fatty acid composition of Malvaceae plants, the seeds of seven Tilia species (lime or linden trees) were evaluated for their fatty acid profiles. Seeds were obtained from the Germplasm Research Information Network and from various commercial sources. After extraction of the seed oil with hexane, the glycerides were trans-methylated and analyzed by gas chromatography on two polar stationary phases. All of the seed oils analyzed were composed primarily of linoleic acid (49-60%) with lesser amounts of oleic (16-22%) and palmitic (8-10%) acids. The usual secondary components were also found. In addition, cyclopropenoid acids (i.e., sterculic and malvalic acids) were present at levels between 6 and 17%. In all samples, the level of malvalic acid was approximately twice the level of sterculic acid, indicating that considerable a-oxidation of sterculic acid had occurred in these seeds. Two additional a-oxidation products, 8-heptadecenoic acid and 8,11-heptadecadienoic acid were also detected. Combined, the level of these fatty acids was between 1.3 and 2.3%, roughly comparable to the levels of these acids recently reported in the seed oil of Thespesia populnea.