Yarrowia lipolytica lipase Lip2: An efficient enzyme for the production of concentrates of docosahexaenoic acid ethyl ester

•Docosahexaenoic acid (DHA, 22:6n-3) reduces the incidence of cardiovascular diseases.•Optimisation of lipase-catalysed hydrolysis of a mixture of ethyl esters from tuna oil.•We optimised an enzymatic process to produce ω3 and DHA concentrates.•The lipase LIP2 from Yarrowia lipolytica, YLL2, is the most effective lipase for DHA purification.•High concentrations of DHA ethyl ester (77%) and ω-3 esters (89.5%) were obtained.

The production of Omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) rich in cis-4,7,10,13,16,19-docosahexaenoic acid (DHA) was studied using lipase-catalysed hydrolysis of a mixture of ethyl esters from tuna oil. Lipases from Yarrowia lipolytica (YLL2), Thermomyces lanuginosus (TLL) and Candida rugosa (CRL1, CRL3 and CRL4) were tested. C. rugosa lipases discriminated esters on the basis of their chain length, with less affinity for γ-linolenate, 11-eicosenoate, arachidonate, EPA, DPA and DHA ethyl esters. However, YLL2 and TLL improved discrimination towards DHA, as enzyme selectivity was shown to be mainly based on the position of the double bond closest to the carboxylic group. From the point of view of kinetics, purity and yield, YLL2 was the most effective lipase for DHA purification. Using this enzyme in an open reactor process resulted in the highest concentrations of DHA ethyl ester (77%) and ω-3 esters (81%) with a recovery of 94% and 77% respectively.