Production of olive oil enriched with medium chain fatty acids catalysed by commercial immobilised lipases

Structured triacylglycerols, containing medium chain fatty acids, were produced by acidolysis of virgin olive oil with caprylic or capric acid, at a molar ratio of olive oil:fatty acid of 1:2, at 45 °C for 24 h, in solvent-free media or in n-hexane, catalysed by Thermomyces lanuginosa (Lipozyme TL IM), Rhizomucor miehei (Lipozyme RM IM) and Candida antarctica (Novozym 435) immobilised lipases. Incorporations were always greater for capric than for caprylic acid. For both acids, higher incorporations were always attained in solvent-free media: the highest caprylic acid incorporations were obtained with Novozym 435 (25.5 mol%) and Lipozyme RM IM (25.7 mol%), while similar capric acid incorporations were obtained with all biocatalysts (27.1–30.4 mol%). After 10 repeated uses of Lipozyme RM IM, the same incorporation level of capric acid was obtained at the end of each 23 h batch. However, with caprylic acid, a first-order deactivation was observed (half-life time, t1/2 = 299 h). During acidolysis with both acids, Novozym 435 (t1/2 = 217 h, for caprylic, t1/2 = 225 h, for capric acid) and Lipozyme TL IM (t1/2 = 50.4 h, for caprylic; t1/2 = 47.2 h, for capric acid) presented first-order deactivation. All biocatalysts presented 1,3-regioselectivity.