Assessing the efficiency of ethyl acetate for lipid extraction as an alternative to the Folch method in selected marine low-trophic species

Abstract

The recognized health benefits associated with marine omega-3 polyunsaturated fatty acids (PUFAs) have increased their demands and prices, prompting the search for new marine materials as lipid sources. Considering stricter health, safety, and environmental regulations, it is crucial to advocate the transition from chlorinated solvents like chloroform and dichloromethane to sustainable alternatives. This study aimed to assess the lipid extraction efficiency of the ethyl acetate (EtOAc) method compared to the Folch method across four marine resources. The tested species were Atlantic salmon (Salmo salar Linnaeus, 1758) and three low-trophic species: the zooplankton Calanus finmarchicus (Gunnerus, 1770), the microalgae Porosira glacialis (Grunow) Jörgensen, 1905, and the macroalgae Saccharina latissima (Linnaeus). Our results indicated that the EtOAc method is as efficient as the Folch method in extracting lipids from Atlantic salmon fillets and freeze-dried C. finmarchicus (p > 0.05). However, the relative lipid yields from frozen and freeze-dried P. glacialis and S. latissima were 49.5% and 27.3%, respectively, when substituting the Folch method with the EtOAc method. Therefore, we recommend the adoption of EtOAc as a sustainable alternative for materials high in neutral lipids to avoid the underestimation of polar and complex lipids. However, the proportion of PUFAs in the extracted lipids was determined not only by the choice of solvent but also by the biological composition of the materials. We encourage future efforts to choose a suitable lipid extraction method considering the characteristics of the raw materials and their composing lipids, in addition to the trade-offs between extraction efficiency and sustainability.