Obtaining of polyunsaturated fatty acids concentrates by the urea complexes method

Abstract

A concentration process for polyunsaturated fatty acids (PUFAs n-3) stearidonic (18:4 n-3), eicosapentaenoic (20:5 n-3) and docosahexaenoic (22:6 n-3) from cod liver oil using urea method has been thoroughly studied. The influence of urea/fatty acid ratio and crystallization temperature have been studied on both fatty acids recovery yield and fatty acid concentration. Methanol and ethanol have been used as urea solvent. The use of methanol and an urea/fatty acid ratio of 4:1, and 4°C were found to be the best conditions for SA (concentration 8,5%, yield 71,6) and DHA (59,8% and 100%, respectively). However, 28ºC was found to be the best temperature for EPA (28,7% and 75,6%, respectively). At temperatures below -12ºC, PUFAs also developed adducts compounds, mainly adducts derived from EPA. A variance analysis showed the urea/fatty acid ratio as the main factor affecting fatty acid concentration. At the same time, high urea/fatty acid ratios resulted in increased influence of the solvent used, being more favorable for methanol.

Keywords

• cod liver oil
• polyunsaturated fatty acid (obtaining)
• urea complexes method