Concentration of eicosapentaenoic acid (EPA) by selective alcoholysis catalyzed by lipases

Abstract

In this work eicosapentaenoic acid (EPA) enriched acylglycerols were obtained from tuna and sardine oils (9 and 19% weight EPA, respectively) by selective ethanolysis catalyzed by lipases. First, eight immobilized lipases were tested and the best EPA concentration and recovery were attained with lipases QLC® and QLG® from Alcaligenes sp. Lipase QLG® was selected to study the influence of reaction time, temperature and lipase/oil and ethanol/oil ratios. Under the optimized conditions attained (48 h, 20°C, lipase/oil ratio 20% w/w and ethanol/oil molar ratio 2.3:1) and for 59.4% conversion, acylglycerols were obtained with 38.6% EPA and 81.6% recovery from sardine oil. In these optimized conditions the reaction was scaled up to 233 g of sardine oil and carried out in a batch stirred tank reactor, with the lipase contained in a cartridge filter attached to the stirring rod. In this reactor, for 54.8% conversion, acylglycerols were obtained with 35.9% EPA and 82.1% recovery. The EPA‐enriched acylglycerols were separated from the ethyl esters in a short‐path vacuum distiller. At an evaporation temperature of 200°C, a residue with 87.4% acylglycerols (12.6% ethyl esters) was obtained, with an EPA concentration of 33.8 and 64.4% EPA recovery.Practical applications: Marine oils have been shown to have beneficial effects on human health, including positive effects on atherosclerosis, coronary heart disease, inflammatory disease, and perhaps even behavioral disorders. They are attributed to the long‐chain n‐3 polyunsaturated fatty acids, mainly eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). However, it is not clear if both EPA and DHA are equally important in cardiovascular protection, because in most oils both species coexist. In this sense, it is necessary to develop large‐scale purification processes to provide sufficient amounts of oils with high concentrations of both PUFAs on the one hand, and with a high concentration of only one of them on the other. This work studies a method to obtain acylglycerols rich in EPA or in EPA and DHA by selective ethanolysis catalyzed by lipases.