Research Article Preparation and characterization of highly stable monodisperse argan oil-in-water emulsions using microchannel emulsification Abdelilah El-Abbassi 1,2 , Marcos A. Neves 1 , Isao Kobayashi 3 , Abdellatif Hafidi 2 and Mitsutoshi Nakajima 1,3 1 Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan 2 Food Sciences Laboratory, Department of Biology, Faculty of Sciences, Semlalia, Cadi Ayyad University, Marrakech, Morocco 3 Food Engineering Division, National Food Research Institute, NARO, Tsukuba, Ibaraki, Japan Argan oil is well known for its nutraceutical properties. Its specific fatty acid composition and antioxidant content contribute to the stability of the oil and to its dietetic and culinary values. There is an increasing interest to use argan oil in cosmetics, pharmaceutics, and food products. However, the formulation of highly stable emulsions with prolonged shelf life is needed. In this study, argan oil-in-water (O/W) emulsions were prepared using microchannel (MC) emulsification process, stabilized by different non-ionic emulsifiers. The effects of processing temperature on droplet size and size distribution were studied. Physical stability of argan O/W emulsions was also investigated by accelerated stability testing and during storage at room temperature (25  28C). Highly monodisperse argan O/W emulsions were produced at temperatures up to 708C. The obtained emulsions were physically stable for several months at room temperature. Furthermore, emulsifier type, concentration, and temperature were the major determinants influencing the droplet size and size distribution. The results indicated that a suitable emulsifier should be selected by experimentation, since the interfacial tension and hydrophilic–lipophilic balance values were not suitable to predict the emulsifying efficiency. Practical applications: MC emulsification produces efficiently monodisperse droplets at wide range of temperatures. The findings of this work may be of great interest for both scientific and industrial purposes since highly stable and monodisperse argan oil-in-water emulsions were produced which can be incorporated into food, cosmetic, or pharmaceutical formulations. Keywords: Argan oil / Interfacial tension / Non-ionic emulsifier / Oil-in-water emulsion / Stability Received: February 28, 2012 / Revised: July 21, 2012 / Accepted: October 1, 2012 DOI: 10.1002/ejlt.201200085 1 Introduction Argan tree (Argania spinosa) is only endemic in Southwestern Morocco, where the argan forests cover slightly more than 800,000 Ha [1]. Argan oil is well known for its nutraceutical properties, as its specific fatty acid composition and anti- oxidant content contribute to the preservation of the oil and to its dietetic and culinary values [2]. Several studies reported numerous bioactivities of argan oil. It has hypoli- pemiant and antioxidant properties [3], antiproliferative effect on human prostate cancer cell lines [4] and may reduce cardiovascular risk associated with obesity [5]. Recently, an invention concerning the introduction of argan oil for the first time into preparations for enteral and parenteral nutrition was patented [6]. Parental nutrition preparations take the form of argan oil-based, injectable lipid emulsions. On the other hand, enteral nutrition preparations take the form of mixtures prepared with polymeric or mono- meric nutrients of food components incorporating argan oil Correspondence: Mitsutoshi Nakajima, Faculty of Life and Environmental Sciences, Universityof Tsukuba, 1-1-1, Tennoudai, Tsukuba, Ibaraki 305-8572, Japan E-mail: nakajima.m.fu@u.tsukuba.ac.jp Fax: 029-853-3981 Abbreviations: AO, argan oil; CV, coefficient of variation; d av , average droplet diameter (mm); HLB, hydrophilic–lipophilic balance; IT, interfacial tension; MC, microchannel; O/W, oil-in-water emulsion; r, density (kg/m 3 ); r r , density ratio; SBO, soybean oil; s, standard deviation; h, viscosity (mPa s); h r, viscosity ratio 224 Eur. J. Lipid Sci. Technol. 2013, 115, 224–231 ß 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ejlst.com