Research Article Evaluation of emu oil extraction methods and their effects on physical and rheological behavior Lilia L. Me ´ ndez-Lagunas 1 , Ana Marı ´a Pineda Reyes 1 , Leo ´ n Rau ´ l Herna ´ ndez Ochoa 2 and Juan Rodrı ´guez Ramı ´rez 1 1 Instituto Polite ´ cnico Nacional, CIIDIR-Oaxaca, Santa Cruz Xoxocotlan, Oaxaca, Oax. Me ´ xico 2 Universidad Auto ´noma de Chihuahua, Facultad de Ciencias Quı ´micas, Chihuahua, Chih., Me ´ xico In this study we evaluated the efficiency of six extraction methods for emu fat based on the quantification of yield, color, density, refraction index, and rheological behavior. Both physical methods (Bain Marie, rotary evaporator, fusion, ultrasound, and microwave) and chemical methods (solvents) were evaluated. Oil properties were compared with commercial emu oil as a reference. Solvent-based extraction produced the greatest yield (72.8%). Among the physical methods, the greatest yield was produced by the ultrasound method (42.8%). In general, properties were similar to those reported for vegetable oils. The rotary evaporator method showed the greatest difference in total color (DE) in comparison with a commercially-produced reference, while the fusion method showed the smallest DE. No statistically significant differences were found between the density and refraction index of the treated samples and those of the reference. Kinematic viscosity increased significantly in samples extracted via microwave method. All samples displayed pseudoplastic behavior. The data showed a good fit to the power law model (R 2 > 0.90). The consistency coefficient and flow behavior index were determined for all methods. Practical applications: Therapeutic applications for oil have been posited for emu oil. In pharma- ceutical products, oils are used as emollients and as carriers for medicinal substances. The practical importance of an oil depends on its physical properties, thus a thorough understanding of those physical properties is very important for identifying potential applications. These properties are affected by the extraction method employed; the present paper evaluates the effects of a range of extraction methods on yield efficiency, as well as physical and rheological properties. Novel extraction methods such as ultra- sound and microwave are also evaluated in this study. Keywords: Emu oil / Extraction method / Physical properties / Rheological behavior Received: October 11, 2010 / Revised: November 24, 2010 / Accepted: January 10, 2011 DOI: 10.1002/ejlt.201000498 1 Introduction In recent years, interest in lipids obtained from emus (Dromaius novaehollandiae) has increased due to potential applications in the cosmetics and pharmaceutical industries. Recently, a wide range of therapeutic applications for the oil have been claimed [1, 2], e.g., the anti-inflammatory and anti-arthritic activity shown by Snowden and Whitehouse [3] in laboratory animals. Other studies have suggested its use- fulness in tissue restoration, burn treatment, and the treat- ment of skin diseases [4]. In pharmaceutical products, oils are used as emollients and as carriers for medicinal substances. In the cosmetics industry, the hydrating and transdermal effi- cacy of the oil has garnered great interest [5]. Although natural fats were replaced in the past by high-purity hydro- carbon oils, this tendency has been reversed in Europe in recent years due to concerns over dermatologic and toxico- logical safety [6]. Additional corresponding authors: Ana Marı ´a Pineda Reyes, E-mail: veneciaita@hotmail.com; Leo ´ n Rau ´l Herna ´ ndez Ochoa, E-mail: lhernandez@uach.mx; Juan Rodrı ´guez Ramı ´rez, E-mail: jrodrigr@hotmail.com Correspondence: Dr. Lilia L. Me ´ndez-Lagunas, Instituto Polite ´ cnico Nacional, CIIDIR-Oaxaca, Hornos 1003, Santa Cruz Xoxocotlan, Oaxaca, Oax. Me ´xico, C.P. 71230 E-mail: mendezll@hotmail.com Fax þ52(951)5170610 ext. 82703 780 Eur. J. Lipid Sci. Technol. 2011, 113, 780–785 ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ejlst.com