Advances in Lipid Extraction Methods-A Review

Abstract

Extraction of lipids from biological tissues is a crucial step in lipid analysis. The selection of appropriate solvent is the most critical factor in the efficient extraction of lipids. A mixture of polar (to disrupt the protein-lipid complexes) and nonpolar (to dissolve the neutral lipids) solvents are precisely selected to extract lipids efficiently. In addition, the disintegration of complex and rigid cell-wall of plants, fungi, and microalgal cells by various mechanical, chemical, and enzymatic treatments facilitate the solvent penetration and extraction of lipids. This review discusses the chloroform/methanol-based classical lipid extraction methods and modern modifications of these methods in terms of using healthy and environmentally safe solvents and rapid single-step extraction. At the same time, some adaptations were made to recover the specific lipids. In addition, the high throughput lipid extraction methodologies used for liquid chromatography-mass spectrometry (LC-MS)-based plant and animal lipidomics were discussed. The advantages and disadvantages of various pretreatments and extraction methods were also illustrated. Moreover, the emerging green solvents-based lipid extraction method, including supercritical CO₂ extraction (SCE), is also discussed.

Keywords: Bligh and Dyer method; Folch method; Soxhlet extraction; green solvents; lipidomics; pre-treatments; supercritical CO2 extraction.

Figure 1

Comparison of Bligh and Dyer method [8] and Folch method [7] of lipid extraction. * Assumption of 100% or 80% water in the sample. # For quantitative analysis, re-extraction of residues with 100 mL chloroform and rinsing with 50 mL chloroform is recommended.

Figure 2

Illustrations showing the Matyash [12] method of lipid extraction.

Figure 3

Illustrations showing the phase separation in chloroform-based (Folch method and Bligh and Dyer methods) [7,8] and methyl-tert-butyl ether (MTBE; Matyash Method) [12] based extraction methods. Compared to the lipid-rich chloroform layer below the aqueous phase (in chloroform-based extraction). Moreover, the nonextractable matrix, including proteins (forms at the bottom of the tube), can be removed by centrifugation easily.