Enrichment of polyunsaturated fatty acids from seal oil through urea adduction and the fatty acids change rules during the process

Abstract

The seal oil is a good resource of ω-3 polyunsaturated fatty acids (PUFA). Besides being rich in EPA and DHA, it also contains a synergism factor-DPA. Urea adduction is a method that is widely used for the concentration of ω-3 PUFA. The aim of this work was to optimize the concentration conditions (urea/oil ratio, crystallization temperature, and time) for EPA, DPA, and DHA by response surface method and study the change rules of fatty acids during the process. The results showed that the optimal conditions for the enrichment was at 2.38:1 urea/FAEE ratio (w/w) upon crystallization at 15 °C for 2.5 hr. The concentration and recovery were 71.35 and 82.31%, respectively, under the optimal conditions. EPA was more easily to be entrapped into the urea than DPA and DHA. SFA (C14:0, C16:0) can be completely removed by urea adduction, while the urea adduction has limited effect on reducing the content of MUFA (C16:1, C18:1, and C20:1). It is necessary to take other methods to remove it. Practical applications Seal oil is rich in PUFAs (EPA, DPA, and DHA), which are helpful to human health. Urea adduction method is a good way to enrich PUFA from seal oil. The changes in FAEE profiles of the urea inclusion compounds and nonincluded FAEEs versus time is fundamental for a proper design, control, and optimization for the processing of functional seal oil.