Industrial Crops and Products 19 (2004) 113–118 Purification of meadowfoam monoestolide from polyestolide Terry A. Isbell ∗ , Steven C. Cermak New Crops and Processing Technology Research, National Center for Agricultural Utilization Research, Agricultural Research Service-USDA, 1815 N. University Street, Peoria, IL 61604, USA Received 12 December 2002; accepted 22 July 2003 Abstract Cosmetic applications using meadowfoam estolide require products of high purity and low color. To meet these two require- ments, meadowfoam estolide was fractionated into monoestolide (dimer) and polyestolide (oligomers) by short-path molecular distillation. The distilled monoestolide had a Gardner Color of one compared with the undistilled material with a Gardner of 12. Flow rates and rotor temperatures were varied and the resultant fractionation of mono- and polyestolide were observed. Monoestolide in the distillate was increased to 89% (unprocessed material had 64% monoestolide) in a single-pass distillation (rotor temperature = 200 ◦ C) with residual monoestolide concentration in the residue of 18%. Multiple-pass distillation removed all of the monoestolide from the residue fraction. The split ratio (distillate to residue) was highest at the lower flow rate with the highest rotor temperature (325 ◦ C). However, considerable amount of co-distillation of polyestolide (50%) was observed. Rotor temperatures beyond 250 ◦ C gave significant declines in the purity of the distilled monoestolide even though the observed split ratio increased. Residual monoestolide composition in the residue was identical for both the low and high flow rates. In conclu- sion, meadowfoam estolide was successfully distilled into a low-color monoestolide fraction suitable for cosmetic applications using a laboratory molecular distillation unit and high vacuum. © 2003 Elsevier B.V. All rights reserved. Keywords: Molecular distillation; Meadowfoam estolide; Monoestolide; Polyestolide 1. Introduction Meadowfoam estolides are secondary esters of meadowfoam fatty acids where the carboxyl group of one fatty acid adds across the olefin of a sec- ond fatty acid (Isbell and Kleiman, 1996). This acid catalyzed process produces a mixture of oligomeric products as the chemical reaction proceeds. The main product from the acid catalyzed reaction is a dimer, monoestolide (64%). Estolides from a num- ∗ Corresponding author. Tel.: +1-309-681-6235; fax: +1-309-681-6524. E-mail address: isbellta@ncaur.usda.gov (T.A. Isbell). ber of fatty acids have been shown to have desirable low-temperature properties (Isbell et al., 2000 and Cermak and Isbell, 2002a,b) making them suitable for lubricants. However, the current market price of mead- owfoam precludes its use in these markets. Therefore, meadowfoam has been marketed into cosmetics where the estolide has shown good properties for use in hair conditioners (Isbell et al., 2001), but dark colored products have limited its use (Frykman and Isbell, 1999). Frykman and Isbell (1999) have shown that some color reduction is possible by bleaching with sodium borohydride, but further color reduction may be required. A second method for estolide purifica- tion was reported based on chromatography, but this 0926-6690/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.indcrop.2003.07.006