ORIGINAL PAPER Enzymatic Interesterification of Extra Virgin Olive Oil with a Fully Hydrogenated Fat: Characterization of the Reaction and Its Products Manuel Criado Æ Estela Herna ´ndez-Martı ´n Æ Arnoldo Lo ´pez-Herna ´ndez Æ Cristina Otero Received: 21 June 2006 / Revised: 8 May 2007 / Accepted: 28 May 2007 / Published online: 6 July 2007 Ó AOCS 2007 Abstract The lipase-catalyzed interesterification of extra virgin olive oil (EVOO) and fully hydrogenated palm oil (FHPO) was studied in a batch reactor operating at 75 °C. The compositions of the semi-solid fat products depend on the reaction conditions and the initial ratio of EVOO to FHPO. The dependence of the quasi-equilibrium product TAG profile on the reaction time was determined for initial weight ratios of EVOO to FHPO from 80:20 to 20:80. Lipozyme TL IM, Lipozyme RM IM and Novozym 435 were employed as biocatalysts. The interesterification reaction was optimized with respect to the type and loading of biocatalyst. Equilibrium was approached in the shortest time with Novozym 435 (80% conversion in 4 h). The chemical, physical, and functional properties of the prod- ucts were characterized. Appropriate choices of the reac- tion conditions and the initial ratio of EVOO to FHPO lead to TAG with melting profiles and solid fat contents similar to those of commercial products. Differences were ob- served in the solid fat contents, melting profiles, and oxi- dative stabilities of the various interesterified products and also between the indicated properties of each category of product and the corresponding physical blend of the pre- cursor reagents. Keywords Candida antarctica  HPLC-mass spectroscopy  Lipase  Interesterification  Margarines  Extra virgin olive oil  Semisolid fat  Zero trans fats Introduction The physical characteristics of oils and fats are deter- mined by their chemical compositions [chain length and degree of unsaturation of fatty acid (FA) residues, as well as the distribution of FA residues along the glycerol backbone]. Enzymatic interesterification (IE) is an emerging method for modifying the physico-chemical properties of fats and oils. EI permits one to incorporate greater amounts of hard fats (e.g., palm stearin and palm kernel olein) in fat based spreads than is possible in simple physical blends of the precursor TAG [1]. Thus, softer products with lower melting points and with no phase separation problems can be produced by EI of a hard fat with a vegetable oil. Consequently, interesterified shortenings are softer than the corresponding (non-inter- esterified) physical mixtures and undergo minimal chan- ges during storage. Enzymatic processes based on the use of either sn-1,3 specific or nonspecific lipases are advantageous over chemical interesterification (CI) because of their enhanced selectivity (generation of fewer undesired byproducts compared to CI), mild reaction conditions (temperatures lower than 100 °C), ease of product recovery [2], reduced losses of oil/fat, fewer process steps, lower requirements of investment capital, and, decreased degradation of toc- opherols. The most important disadvantage of EI is the M. Criado  E. Herna ´ndez-Martı ´n  C. Otero Department of Biocatalysis, Institute of Catalysis and Petrochemistry, CSIC, Cantoblanco, Madrid 28049, Spain A. Lo ´pez-Herna ´ndez Department of Chemical and Biological Engineering, University of Wisconsin, Madison, WI 53706-1691, USA C. Otero (&) Instituto de Cata ´lisis, C/Marie Curie 2, 28049 Cantoblanco, Madrid, Spain e-mail: cotero@icp.csic.es 123 J Amer Oil Chem Soc (2007) 84:717–726 DOI 10.1007/s11746-007-1104-y