Enzymatic interesterification between pine seed oil and a hydrogenated fat to prepare semi-solid fats rich in pinolenic acid and other polyunsaturated fatty acids

Enzyme catalyzed interesterification (EIE) of pine seed oil (PSO) and a fully hydrogenated soybean oil (FHSBO) were studied in batch reactors in solvent-free media to prepare different semisolid fats rich in polyunsaturated fatty acids (PUFA). Optimal operation conditions found were: 10 % (w/w) enzyme loading, 75 C and magnetic agitation at 300 rpm. Quasi-equilibrium conditions were reached after 2, 3 and 6 h, when immobilized lipases from Thermomyces lanuginosus (Lipozyme® TL IM), Candida antarctica B. (Novozym® 435) and Rhizomucor miehei (Lipozyme® RM IM) from Novozymes A/S (Bagsvaerd, Denmark) were employed, respectively. Similar distributions of unsaturated to saturated fatty acid (UFA/SFA) residues along the glycerol backbone of the fat products were obtained with both non-selective and sn-1(3) regioselective lipases due to significant spontaneous acyl migration during the reaction. The products had higher UFA/SFA ratios at the sn-2 position (2.4-2.5, 1.4-1.7, and 0.5-0.8 for the trials involving 20, 40 and 70 % FHSBO, w/w, respectively) than the corresponding physical blends (0.8, 0.4 and 0.5, respectively). Fat products containing 3.1-11.6 % (w/w) pinolenic acid (Pn) and 16.1-35.7 % (w/w) linoleic acid (L) at the sn-2 position were prepared. The free acid contents of EIE products prepared with Lipozyme ® TL IM and Novozym® 435 were 6.1-6.4 and 2.5-2.6, respectively. Residual activities of Lipozyme® TL IM and Novozym® 435 diminish by ca. 20 % after 9 reaction cycles.This work was supported by the Spanish CICYT (MAT2007‐6666‐C02‐02). A predoctoral fellowship for E. Hernández‐Martín was provided by the Spanish Research Council, CSIC.Peer Reviewe