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This work aims to produce triacylglycerols (TAG) containing a medium-chain fatty acid (M) at positions sn-1,3 and a long-chain fatty acid (L) at sn-2 position, i.e. TAG of MLM type, by acidolysis of virgin olive oil with caprylic (C8:0) or capric (C10:0) acids, catalyzed by 1,3-selective Rhizopus oryzae heterologous lipase (rROL) immobilized in Eupergit Ò C and modified sepiolite. This lipase was produced by the methylotrophic yeast Pichia pastoris. Reactions were performed at 25 and 40°C, for 24 h, either in solvent-free or in n-hexane media, at a molar ratio 1:2 (olive oil:free fatty acid). Higher incorporations of C8:0 (21.6 mol%) and C10:0 (34.8 mol%) into the TAG were attained in solvent-free media, at 40°C, when rROL immobilized in Eupergit Ò C was used. In organic media, at 40°C, only 15.9 and 14.1 mol%, incorporation of C8:0 or C10:0 were, respectively observed. Lower incorporations were attained for both acids (3.4-7.0 mol%) when native ROL (nROL) in both supports and rROL in modified sepiolite were used. rROL in Eupergit Ò C maintained its activity during the first four or three 23-h batches, respectively when C8:0 (half-life time, t 1/2 = 159 h) or C10:0 (t 1/2 = 136 h) were used, decreasing thereafter following a time delay model. Keywords Acidolysis Á Capric acid Á Caprylic acid Á Olive oil Á Rhizopus oryzae lipase Á Structured lipids Abbreviations FFA Free fatty acid(s) L Long-chain fatty acid(s) M Medium-chain fatty acid(s) MAG Monoacylglycerol(s) MLM Triacylglycerol(s) containing medium-chain fatty acid at sn-1 and sn-3 positions (M) and a long-chain fatty acid (L) at position sn-2 nROL Native ROL rROL Heterologous ROL ROL Rhizopus oryzae lipase SL Structured lipid(s) TAG Triacylglycerol(s) t

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