Conversion of olive pomace oil to cocoa butter-like fat in a packed-bed enzyme reactor Ozan Nazım Çiftçi, Sibel Fadılog ˘lu * , Fahrettin Gög ˘üs ß Department of Food Engineering, Faculty of Engineering, University of Gaziantep, 27310 Gaziantep, Turkey article info Article history: Received 20 March 2008 Received in revised form 21 May 2008 Accepted 23 May 2008 Available online 7 July 2008 Keywords: Refined olive pomace oil Lipase Cocoa butter-like fat Packed-bed reactor Acidolysis abstract Refined olive pomace oil (ROPO) was utilized as a source oil for production of cocoa butter-like fat. Immo- bilized sn-1,3 specific lipase catalyzed acidolysis of ROPO with palmitic (PA) and stearic (SA) acids was performed in a laboratory scale packed-bed reactor. Effect of reactor conditions on product formation was studied at various substrate mole ratios (ROPO:PA:SA; 1:1:1, 1:1:3, 1:3:3, 1:2:6), enzyme loads (10%, 20%, 40%), substrate flow rates (1.5, 4.5, 7.5, 15 ml/min) and solvent amounts (150, 400 ml). The highest yield (10.9% POP, 19.7% POS and 11.2% SOS) was obtained at 40% enzyme load, 1:2:6 substrate mole ratio, 45 °C, 7.5 ml/min substrate flow rate, 150 ml solvent and 3 h reaction time. The melting pro- file and SFC of the product were comparable to those of CB. Polarized light microscope (PLM) images showed no drastic changes in polymorphic behavior between CB and product. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Cocoa butter (CB) is a highly valued ingredient primarily used in the chocolate industry (Lipp et al., 2001). Of all the ingredients present in chocolate, none has more influence on its physical and chemical properties than CB, which is responsible for the different favorable characteristics such as hardness at room temperature, brightness and fast and complete melting when placed in the mouth (Saldana et al., 2002). CB is composed of three main triacyl- glycerols (TAGs): 16% 1,3-dipalmitoyl-2-oleoyl-glycerol (POP); 36% 1(3)-palmitoyl-3(1)stearoyl-2-oleoyl-glycerol (POS); 26% 1,3- distearoyl-2-oleoyl-glycerol (SOS); with oleic acid at sn-2 position of glycerol backbone (Liu et al., 2007). Due to high cost and fluctu- ations in the supply and demand of CB, industry investigated use- fulness of other vegetable fat and oil sources as an alternative to CB (Lipp and Anklam, 1998). Cheap commercial oils can be converted to high value added products by enzymatic lipid modification reactions (Forssell et al., 1992). Production of CB-like fats from cheap oils by lipase cat- alyzed acidolysis is a good example of producing value added prod- ucts. This conversion can be done by using sn-1,3 specific lipases that catalyze incorporation of palmitic acid (PA) and stearic acid (SA) to the sn-1,3 positions of a source oil containing oleic acid at sn-2 position until a similar TAG composition of CB is obtained. Olive pomace oil can be considered as a good potential source for CB-like fat production because of its high sn-2 position oleic acid content and low cost. Olive pomace oil is obtained by sol- vent-extraction from the olive pomace which is left after mechan- ical press of olives. Because of long storage periods of pomace and high temperature drying applications, it is considered of a lower quality. So it is used for soap making and industrial processes. Its chemical composition does not differ from refined olive oil (Kiritsa- kis et al., 1998). Modification of fats and oils by lipases can be achieved either by batch or continuous reactors. Continuous reactors seem to be more advantageous over batch reactors because of ease of operation, in- creased enzyme stability, low investment and reduced acyl migra- tion. Packed-bed reactors have currently received a lot of attention, and several applications have been carried out in lipid modification industry (Xu, 2003). The aim of this study was to produce a CB-like fat from ROPO by enzymatic acidolysis reaction in a packed-bed reactor, to study the basic reaction parameters and bioreactor characteristics, and to characterize the product in terms of TAG content, thermal charac- teristics and microstructure. 2. Methods 2.1. Materials ROPO was kindly provided by Bilginog ˘lu Marbil Yag ˘ San. ve Tic. AS ß., _ Izmir, Turkey. Some selected properties of ROPO are given in Table 1. TAG (triolein (OOO), POP, POS and SOS) and fatty acid stan- dards were obtained from Sigma Chemical Co. (St. Louis, MO). PA (P98% purity) and SA (P97% purity), porcine pancreatic lipase 0960-8524/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2008.05.035 * Corresponding author. Tel.: +90 3423172317; fax: +90 3423601105. E-mail address: fadiloglu@gantep.edu.tr (S. Fadılog ˘lu). Bioresource Technology 100 (2009) 324–329 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech