Castor and Lesquerella: Sources of Hydroxy Fatty Acids

by Lewrene K. Glaser, Agricultural Economist, ERS, USDA, Washington, DC; Joseph C. Roetheli, Industrial Oilseeds Program Manager, CSRS, USDA, Washington, DC; Anson E. Thompson, Research Geneticist, U.S. Water Conservation Laboratory, ARS, USDA, Phoenix, AZ; Raymond D. Brigham, Associate Professor, Texas A&M University Agricultural Research and Extension Center, Lubbock, TX; and Kenneth D. Carlson, Chemist, National Center for Agricultural Utilization Research, ARS, USDA, Peoria, IL.

Recorded use of castor oil dates back at least 4,000 years to when the ancient Egyptians used it in their lamps. In modern times, manufacturers have developed many products, ranging from lipstick to jet-engine lubricants, using castor oil and its derivatives.

Among commercial vegetable and petroleum oils, castor oil has unusual characteristics. Its chemical structure and hydroxy fatty acid content make it valuable for industrial applications.

During the 1950's and 1960's, about 80,000 acres of castor were grown annually on the High Plains of Texas. But domestic production decreased, and was finally abandoned altogether in 1972 when castor oil buyers and the farmer cooperative involved in crushing castor seed were unable to agree on their annual contract because of low world prices for castor oil and high local farm prices for competing crops. Since then, the United States has imported an average of 41,200 metric tons of castor oil per year (see fig. 1).

Because of widely fluctuating world supplies and the structure of the world market, prices for castor oil vary considerably. These supply and price instabilities impose severe handicaps on users. They affect cash flow, make corporate planning difficult, and discourage investment in new products. Therefore, Union Camp Corporation and CasChem, Inc., the major U.S. buyers of castor oil, have worked with Browning Seed, Inc., scientists, and farmers to reestablish domestic castor production on the High Plains of Texas.

Castor dates back to 4,000 years ago, when the Egyptians used its oil in their lamps. In modern times, manufacturers have used it it products ranging from lipstick to jet engine lubricants. USDA BN-13205

Robert Hawkins, consultant and former Union Camp Corporation purchasing agent, is familiar with fluctuating castor oil prices:

"Over the past 20 to 30 years, there usually has been a wild seesaw of world prices and production from one year to the next. World production declines when there is a drought in Brazil or India and prices rise 50 percent or more. Then in subsequent years, because of overplanting, prices drop sharply. They are now at a very low level, $650 per metric ton, compared to $950 per metric ton 3 years ago.

"By encouraging domestic production, we hope to dampen those cycles, so that customers will remain with castor-oil products rather than switch to alternatives when castor oil prices rise. If prices could remain relatively stable, perhaps somewhat higher than they are now, research and market development of castor products could be justified. But it is very hard for any company to support such efforts when you know prices will be very different 2 years down the line."

In contrast to castor, lesquerella has practically no history of cultivation and use. An experimental crop from the genus Lesquerella, it is being studied to provide U.S. manufacturers with a new domestic source of hydroxy fatty acids and U.S. farmers with a new source of income. Industry has noted the progress in crop production research and lesquerella oil's potential as a chemical raw material. As a result, several firms have joined USDA in its developmental efforts. Small acreages are being grown in several States as part of this project.

Hydroxy Fatty Acids

Why all this interest in castor and lesquerella? It is because the primary fatty acids in castor and lesquerella oils are unsaturated hydroxy fatty acids. Because of their special chemical attributes, hydroxy fatty acids are used in a wide range of products, including high-performance lubricants, cosmetics, waxes, nylons, plastics, and coatings.

Fatty acids are the building blocks of all vegetable oils. The chain length and chemical reactivity of a fatty acid help determine its value for industrial purposes. For example, the hydroxyl group (an oxygen and a hydrogen atom) gives castor and lesquerella a fatty acids special properties, such as higher viscosity and reactivity compared with other fatty acids. Furthermore, unsaturation (one or more double bonds within the carbon chain) provides additional sites for chemical reactions to occur. Castor and lesquerella oils offer two chain lengths and two types of unsaturation for novel reactivity and strategic applications. These attributes mean more opportunities to make different products and are a prime reason for industry's interest in hydroxy fatty acids.

Crop Characteristics

Native to Africa, castor (Ricinus communis L.) is grown throughout the world. In temperate climates, it is an annual crop. Improved dwarf-internode varieties and hybrids developed in the United States range from 4 to 6 feet in height. Castor seeds, which contain over 50 percent oil on a dry-weight basis, are mottled brown and about the size of pinto beans. Almost 90 percent of the oil is ricinoleic acid.

Lesquerella is native to North America, ranging from Alaska to Alabama. The greatest concentration of species occurs in the southwestern United States and northern Mexico. Of the 23 lesquerella species scientists have studied, Lesquerella fendleri, a winter annual, has the best agronomic potential. Its tiny, dark-yellow seeds contain over 25 percent oil on a dry-weight basis, and about 55 percent of that is lesquerolic acid.

Considerable genetic variation has been observed both within the genus and in L. fendleri, which appears to be highly cross-pollinated. These characteristics provide plant breeders with opportunities to improve the oil content of the seed and the amount of hydroxy fatty acids in the oil. There is also an opportunity to breed for desirable characteristics such as increased yield, erect growth, and other traits needed in a commercial oilseed crop.

Production practices for castor and lesquerella would be familiar to many farmers. Except for castor harvesting, both crops can be grown with only minor modifications to existing equipment. Special planting plates or air planters are used to handle fragile castor seeds. Planters and combines for lesquerella should be adjusted to handle its small seed. Cultural practices for castor are similar to those for cotton, corn, and sorghum, while lesquerella can be grown in a cropping system very similar to that used for winter wheat and other small grains in the Southwest. Overall, pesticide and fertilizer use may be lower than with traditional crops. Browning Seed, Inc., has developed an improved castor harvester-huller, which will lower harvesting costs and remove a major barrier to domestic production.