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Optimized Production of MLM Triacylglycerols Catalyzed by Immobilized Heterologous Rhizopus oryzae Lipase

Nunes, P. A., Pires-Cabral, P., Guillén, M., Valero, F., Ferreira-Dias, S.
journal of the American Oil Chemists' Society 2012 v.89 no.7 pp. 1287-1295
fatty acids, fermentation, Komagataella pastoris, yeasts, models, triacylglycerols, triacylglycerol lipase, response surface methodology, Rhizopus oryzae, virgin olive oil, temperature, acidolysis
Response surface methodology was used to model and optimize the acidolysis of virgin olive oil with caprylic (C8:0) or capric (C10:0) acids, aimed at the production of low caloric triacylglycerols (TAG) of MLM type, in solvent free media, catalyzed by the heterologous Rhizopus oryzae lipase (r-ROL) immobilized in Eupergit® C. This lipase was produced in the methylotrophic yeast Pichia pastoris Muts phenotype (experiments with C10:0) or a Mut+ phenotype (experiments with C8:0), under different operational conditions. The r-ROL used in experiments with C10:0 presented a hydrolytic activity about 5 times of that presented by r-ROL used in acidolysis with C8:0. The experiments were carried out following a central composite rotatable design, as a function of the molar ratio (MR) medium chain fatty acid/TAG (1.6–4.4) and temperature (25–55 °C). Convex surfaces described by second order polynomials as a function of MR and temperature were well fitted to fatty acid incorporation values. After 24-h reaction, the predicted maximum incorporation of caprylic (15.5 mol%) or capric (33.3 mol%) acids in olive oil occurs at 37 and 35 °C, respectively, and at C8:0/TAG of 2.8:1 or C10:0/TAG of 3:1. These predicted optima were experimentally validated. Fermentation conditions used in r-ROL production highly affected hydrolytic activity and to a lesser extent interesterification activity.