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. 2019 Apr 26;24(9):1642.
doi: 10.3390/molecules24091642.

Concentration of EPA and DHA From Refined Salmon Oil by Optimizing the Urea⁻Fatty Acid Adduction Reaction Conditions Using Response Surface Methodology

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Concentration of EPA and DHA From Refined Salmon Oil by Optimizing the Urea⁻Fatty Acid Adduction Reaction Conditions Using Response Surface Methodology

Gretel Dovale-Rosabal et al. Molecules. .
Free PMC article


This research focused on obtaining eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3) (EPA+DHA) concentrates from refined commercial salmon oil (RCSO). Independent variables of the complexation process were optimized by means of the application of response surface methodology (RSM) in order to obtain the maximum content of such fatty acids (FAs). As a result of employing the optimized conditions for all the variables (6.0, urea:FA content ratio; -18.0 °C, crystallization temperature; 14.80 h, crystallization time; 500 rpm, stirring speed), high contents of EPA and DHA could be obtained from RCSO, achieving increases of 4.1 and 7.9 times in the concentrate, with values of 31.20 and 49.31 g/100 g total FA, respectively. Furthermore, a 5.8-time increase was observed for the EPA + DHA content, which increased from 13.78 to 80.51 g/100 g total FA. It is concluded that RCSO can be transformed into a profitable source of EPA and DHA (EPA+DHA), thus leading to a product with higher commercial value.

Keywords: DHA; EPA; EPA+DHA; desirability function; multiple response optimization; n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFAs) concentration; process variable maximization; refined commercial salmon oil; response surface methodology (RSM); total FA yield.

Conflict of interest statement

The authors declare no conflict of interest.


Figure 1
Figure 1
Pareto charts and response surfaces for the effects of different process variables: Panels in total FA yield (%, panels A,B), EPA content (g/100 g total FA, panels C,D), DHA content (g/100 g total FA, panels E,F), EPA+DHA content (g/100 g total FA, panels G,H). A: urea/FA contents ratio, w/w; B: crystallization temperature, °C; C: crystallization time, h; and D: stirring speed, rpm).
Figure 2
Figure 2
Combination of factors to maximize the desirability function for RCSO concentrate: response surface (A) and contour surface (B).

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