ORIGINAL PAPER Response Surface Modeling of Processing Parameters for the Preparation of Phytosterol Nanodispersions Using an Emulsification–Evaporation Technique Wai-Fun Leong • Kok-Whey Cheong • Oi-Ming Lai • Kamariah Long • Yaakob B. Che Man • Misni Misran • Chin-Ping Tan Received: 8 November 2009 / Revised: 5 October 2010 / Accepted: 5 November 2010 / Published online: 23 November 2010 Ó AOCS 2010 Abstract The purpose of this study was to optimize the production parameters for water-soluble phytosterol nan- odispersions. Response surface methodology (RSM) was employed to model and optimize three of the processing parameters: mixing time (t) by conventional homogenizer (1–20 min), mixing speed (v) by conventional homoge- nizer (1,000–9,000 rpm) and homogenization pressure (P) by high-pressure homogenizer (0.1–80 MPa). All responses [i.e., mean particle size (PS), polydispersity index (PDI) and phytosterols concentration (Phyto, mg/l)] fitted well to a reduced quadratic model by multiple regressions after manual elimination. For PS, PDI and Phyto, the coefficients of determination (R 2 ) were 0.9902, 0.9065 and 0.8878, respectively. The optimized processing parameters were 15.25 min mixing time, 7,000 rpm mixing speed and homogenization pressure 42.4 MPa. In the pro- duced nanodispersions, the corresponding responses for the optimized preparation conditions were a PS of 52 nm, PDI of 0.3390 and a Phyto of 336 mg/l. Keywords Phytosterol  Nanodispersion  Response surface methodology  High-pressure Abbreviations AAD Absolute average deviation A i Peak area of internal standard A s Area of sample A st Peak area of standard R 2 Coefficient of determination P Homogenization pressure PDI Polydispersity index Phyto Phytosterol concentration PS Mean particle size RRF Relative response factor RSM Response surface methodology t Mixing time v Mixing speed V i Amount of internal standard V st Amount of the standard Introduction Dietary plant sterols or phytosterols are naturally occurring steroid alcohols found exclusively in plants. These fat derivatives are essential constituents of plant cell mem- branes, and they can be classified into three groups based on their biosynthesis and structure: 4-desmethyl sterols, 4-methyl sterols and 4,4-dimethyl sterols. Nevertheless, only 4-desmethyl sterols have been shown to reduce low W.-F. Leong  K.-W. Cheong  Y. B. Che Man  C.-P. Tan (&) Department of Food Technology, Faculty of Food Science and Technology, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor, Malaysia e-mail: tancp@putra.upm.edu.my O.-M. Lai Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor, Malaysia K. Long Malaysian Agricultural Research and Development Institute (MARDI), P.O. BOX 12301, 50774 Kuala Lumpur, Malaysia M. Misran Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia 123 J Am Oil Chem Soc (2011) 88:717–725 DOI 10.1007/s11746-010-1714-7