Fractionation of omega-3 fatty acids or their derivatives with multiple separation technology

摘要

Preparation of nutrients concentrates is important in food and pharmaceutical industries. Although multiple separation technologies involving physical, chemical, and biotechnological processes are available for use, such separations can be difficult due to similarity of constituents to be separated or their sensitivity to process conditions used. In this work, we have conducted studies on the concentration of omega-3 fatty acids from natural sources. Flaxseed oil has a high content of linolenic acid (56.2%) and its content can be further enriched by urea complexation or crystallization. By urea complexation, a purity of 82.9% was achieved in a single step using an urea/fatty acid ratio of of 3/1(w/w). A two-step operation increased the yield from 29.8 to 34.7% without affecting the purity. Use of a higher solvent (absolute ethanol)/fatty acid ratio improved the yield to 44.5%. Athough crystallization furnished better yields than urea complexation, the purity was low. One-step crystallization using acetone (1/5, acids/acetone, v/v) gave 67.8% linolenic acid..Doubling the amount of acetone removed 22.5 and 26.5% more palmitic and stearic acid during process. However, it did not improve the purity. Ethyl esters from a high-DHA (docosahexaenoic acid) single cell oil were produced by step-wisealcoholysis in a three-batch reaction catalyzed by Novozym 435 giving yields of 88.7, 93.5 and 96.7%. The ethyl esters were separated by short path distillation (SPD) at evaporation temperatures from 70 to 120 °C. The content of DHA in the distillates increased from 1.9 to 34.1%. The purity of DHA after SPD can be enriched from 53.7 to 88.8% after SPD with 61.5% of yield.