Robert Kleiman

Acid-Catalyzed Condensation of Oleic Acid into Estolides and Polyestolides

Oleic acid, when treated with 1.0 equivalent of perchloric acid at 50°C, produced a 76% yield of polyestolide. The concentration of mineral acid greatly affected the rate of estolide formation, with increased rates under high acid concentrations. Over a range of temperatures from room temperature to 100°C, reaction rates increased at higher temperatures. However, high acid concentrations and temperatures produced undesirable side products, primarily lactones. Other acids catalyze the condensation of oleic acid to form estolide with the following relative rates: HClO4 >H2SO4>p-toluenesulfonic>BF3·Et2O> montmorillonite K-10>HCl>H3PO4, HNO3. Addition of water impedes the formation of estolide.

Characterization of Estolides Produced from the Acid"Catalyzed Condensation of Oleic Acid

Estolides produced from an acid-catalyzed condensation of oleic acid were characterized by high-performance liquid chromatography (HPLC), gas chromatography (GC), GC-mass spectrometry (MS) and nuclear magnetic resonance (NMR). C-8 reverse-phase HPLC provided a clean resolution of the estolide oligomers present in the reaction mixtures, allowing an average oligomier distribution to be calculated. Corroboration of HPLC results were obtained either through hydrolysis of the estolide mixture and quantitation of the hydroxy fatty acid content by GC, through the integration of the α-methylene protons adjacent to the carbonyl of the acids vs. the esterns in the1H NMR spectrum, or by titration of the carboxylic acid with standardized base. GC and GC-MS analysis of the hydrolyzed estolide mixture indicated that the ester position were centered around the original double-bond position, with linkages ranging from positions 5–13. Likewise, the unsaturation was distributed along the fatty acid backbone.

Collection and evaluation of new Lesquerella and Physaria germplasm

Lesquerella and the closely related genus Physaria are prime candidates as a new, alternative source of hydroxy fatty acids (HFA) for industrial uses. At present, castor oil is the only natural source of these HFA for commerce. To expand the germplasm base of these taxa for our breeding program and the National Germplasm System (NPGS), we collected species from a wide geographic region in the United States. In 1993, 44 accessions of Lesquerella fendleri, 38 accessions from nine other Lesquerella species, and three accessions of two different Physaria species were obtained. In 1994, 41 additional accessions of L. fendleri and 51 accessions of ten other Lesquerella species were collected. A total of 20 different species of Lesquerella and two Physaria species were collected over the two years. Oil characteristics and seed size of eight of these Lesquerella and one Physaria species have not previously been reported. Twelve of these taxa have not been available in the NPGS. Populations of L. fendleri collected in Arizona had higher seed-weights than those collected from Texas and New Mexico. Some of the new accessions had seed-weights higher than germplasm presently in the USDA-ARS breeding program. Diverse growth habits were found in populations from all three states. We believe that other species of Lesquerella and Physaria could later be developed as a source of HFA in regions other than the arid southwestern United States. Accessions of Lesquerella douglasii had the same or higher seed-oil content than L. fendleri and also higher seed yields. Two accessions of Physaria newberryi had seed-weights that ranged between 4.5 and 6.2 g/1000 seeds compared to that of 0.25 to 1.1 g/1000 seeds for L. fendleri. Seed-oil contents of P. newberryi averaged 30.8% compared to 23.8% for L. fendleri. Preliminary seed increase and evaluation of oil content and composition were completed on 14 L. fendleri populations from the 1993 collection under field conditions in Phoenix, Arizona. Accessions were compared to the original populations collected in 1993 and 1994 for growth habit, seed size, and seed-oil content and quality.

Composition of seed oils in some Latin American Cuphea (Lythraceae)

Abstract Cuphea is unique among all flowering plants for the diversity of medium chain fatty acids produced as dominant fatty acids in the seed oils. The genus is a focus of research as a renewable source of MCTs for use by the chemical, food and health industries and as a model organism for the elucidation of biosynthesis of fatty acids. Seed oil composition is reported in 15 taxa, including 13 species previously unstudied. Results mostly substantiate patterns established in earlier studies in which species emphasize production of a single fatty acid, either C8:0, C10:0, C12:0, C14:0 or C18:2. Three species are unusual in producing equal amounts of C8:0 and C10:0, C12:0 and C14:0, and C10:0-C12:0-C14:0, respectively. In C. pulcherrima, 94% of total seed oil composition is caprylic acid (C8:0) and in C. schumanni, 94% is capric acid (C10:0). These are the highest single fatty acid percentages reported in the genus. Representatives of sect. Ornithocuphea are analysed for the first time and new compositional seed oil patterns are reported in sections Brachyandra and Melvilla.

Composition of Chilean jojoba seeds

Abstract Liquid wax ester extracted from the seeds of the jojoba plant (Simmondsia chinensis) is used commercially in the cosmetics industry. For this reason, it is a potentially profitable crop for the arid regions of Chile. This study evaluates the yields, and physical and chemical properties of jojoba seeds grown experimentally in Chile, compared with literature values and commercial sources in the United States, Israel, Peru, and Argentina. Cuttings from promising jojoba plants were gathered from abandoned plantations in various arid regions of Chile and propagated for study at a Chilean research station. Seed samples originating from 17 selected clones were analyzed for oil content, weight per 1000 seeds, and protein and simmondsin contents. The seed oil was analyzed for acid value, wax ester profile, fatty acid profile and fatty alcohol profile. The Chilean seeds had physical properties similar to commercial sources and literature values. However, there were differences in the chemical composition. The molecular weights of the wax esters and their fatty acid moieties were significantly higher than the literature values and commercial seed samples. The wax ester profile of the Chilean seeds had higher C42 and lower C38 content than the commercial sources. In addition, the total simmondsins content in the Chilean seed was higher than literature values and the simmondsin content with respect to its analogs (simmondsin ferulate, demethylsimmondsin (DMS), and didemethylsimmondsin (DDMS)) was considerably lower.

1,3-specific lipolysis ofLesquerella fendleri oil by immobilized and reverse-micellar encapsulated enzymes

Three types of reaction systems, all batch-mode, were employed for production of hydroxy (lesquerolic and auricolic) fatty acidsvia 1,3-specific lipolysis ofLesquerella fendleri oil: “Free”Rhizopus arrhizus or immobilizedRhizomucor miehei lipase (Lipozyme™) in reverse micelles (System 1), Lipozyme suspended in lesquerella oil/isooctane mixture (System 2) and a suspension of water and freeR. miehei lipase in lesquerella oil/isooctane (System 3). The objective was to find the system that best maximized yield (i.e., percent hydrolysis), the proportion of hydroxy acids among the free acids liberated (hydroxy acid “purity”), and recovery/reuse of lipase activity, and that could be easily adapted into a large-scale process. System 1 provided the largest percent hydrolysis (55%) and hydroxy acid purity (85%), but of the three systems would be the most difficult to scale up. Thus, System 1 would be the most desirable reaction system only when small batch sizes are to be processed. System 3 yielded 47.2% hydrolysis, but the hydroxy acid purity was at most 73%, making it the least desirable of the three systems to employ. System 2 yielded moderate extents of hydrolyses (30–40%) and large hydroxy acid purity initially (80–83%), but the purity decreased slightly in the latter stages of the reaction due to acyl migration. System 2 was the system most easily adaptable to a large-scale process, making it the method of choice. For System 2 reactions, only when the medium was initially saturated with water and water consumed by the reaction was continuously replaced could 30–40% hydrolysis be achieved. External mass transfer limitations for Lipozyme-catalyzed reactions were not present when the solution’s water content was not above saturation, and its kinematic viscosity, controlled by the temperature and the proportion of isooctane, was below 41 centistokes.

Vulcanized meadowfoam oil

The factice gelation time for meadowfoam oil, along with hardness, color, acetone extract and free sulfur content of the gelled products were compared with gelation time and product properties of factice prepared from seed oils of rapeseed, crambe, soybean, castor,Lesquerella and jojoba. The effect of additives, specifically zinc oxide, magnesium oxide, triethylamine, dicyclohexylamine, 2-mercaptobenzothiazole and iodine, was also investigated. Both white and brown factices could be prepared from meadowfoam oil and their properties were equivalent to or better than those from high erucic acid rapeseed oil used commercially for the highest quality factice.

Characterization of monomers produced from thermal high-pressure conversion of meadowfoam and oleic acids into estolides

The monomers produced from thermal high-pressure conversion of meadowfoam or oleic acids into estolides were characterized as a complex mixture of fatty acids. Mild reaction conditions produced little change in the starting acids. However, vigorous reaction conditions,e.g. ≥3 h at 250°C with stirring, significantly altered the starting fatty acids.Cis/trans isomerization occurred readily, with the proportion oftrans isomers reaching 57%. In addition, the double bonds migrated throughout all positions of the hydrocarbon chain with concentrations diminishing outward from the starting double bond position. Branching was also observed to a small extent under these conditions and was even more pronounced in the absence of water. Lactones were also identified in the reaction mixture, with contents near 16% in the meadowfoam series. All products can be explainedvia carbocation rearrangement mechanisms that result from protonation of the starting olefins.

The isolation and recovery of fatty acids with Δ5 unsaturation from meadowfoam oil by lipase-catalyzed hydrolysis and esterification

This report examines the use of lipases for isolating fatty acids with Δ5 unsaturation from the seed oil ofLimnanthes alba, or meadowfoam. Seven lipase types and three enzyme configurations (immobilized, “free” and reversemicellar encapsulated) were examined. All lipases discriminated against Δ5 acids to varying degrees, but the degree of discrimination was independent of enzyme configuration. Lipase-catalyzed esterification of meadowfoam oil’s free fatty acids was much more successful for isolating Δ5 acyl groups than was lipolysis. For example, esterification directed byChromobacterium viscosum lipase yielded a free fatty acid product containing >95% of the Δ5 acyl groups at >99% purity.

Chemical survey and erucic acid content of commercial varieties of nasturtium, Tropaeolum majus L.

Nasturtium (Tropaeolum majus L.) oil contains the highest levels of erucic acid of known seed oils (75–80%). A significant portion of the acid is attached to the 2-position of the glycerol, and trierucin is a major component (ca. 50%) of the oil. Seeds from eleven varieties of commercially available garden nasturtium (T. majus) were screened for oil content, erucic acid levels and fatty acid distribution. Oil contents ranged fromca. 6 to 11%, and erucic acid levels in the oils ranged from 62 to 80%. One sample ofT. speciosum was also analyzed, and contained 28% oil, fatty acids from C16 to C28 and triglycerides up to C72.