Lipid Extraction Essay

1101 Words 4 Pages
The major bottleneck for lipid extraction from the wet microalgae is the low extraction efficiency, because of the immiscibility of nonpolar organic solvents with water contained in wet microalgae {Yoo, 2012 #31} {Kim, 2013 #118}. Traditional method for lipid extraction from dry biomass uses a co-solvent system, which consist of a non-polar solvent and polar solvent {Halim, 2012 #7} {Kim, 2013 #118}. When the co-solvent system is directly applied to wet microalgal biomass, the microalgal cells tend to stay in the hydrophilic phase because of their negatively charged surface, limiting the direct contact between hydrophobic extraction solvents and the microalgal cells {Huang, 2013 #1} {Yoo, 2012 #31} {Kim, 2013 #118}. Therefore, the drying process …show more content…
4 shows the possible mechanism of microalgal lipid extraction by organic solvent. Because of the interaction between their long hydrocarbon chains, neutral lipids bound to each other by hydrophobic interaction to form globules in the cytoplasm {Medina, 1998 #3}. During lipid extraction by co-solvent system, the nonpolar organic solvent penetrates though the microalgal cell envelope and interacts with the neutral lipids in globule form by van der Waals interaction to form a nonpolar solvent-neutral lipid complex {Medina, 1998 #3}{Halim, 2012 #7}. This solvent-lipid complex diffuses out of the cytoplasm by concentration gradient, and the extracted lipids remain dissolved in the solvent system outside of the cells {Halim, 2012 …show more content…
Because of the hydrogen bond between polar lipids and membrane protein, the complex is strongly linked to the microalgal cell membrane {Medina, 1998 #3}{Halim, 2012 #7}. The co-solvent system penetrates into the microalgal cytoplasm and interacts with the neutral lipid-polar lipid complex, which is linked to the cell membrane {Halim, 2012 #7}. When the lipid complex is exposed to the co-solvent system, the nonpolar organic solvent attracts the neutral lipid into complex by van der Waals interaction, whereas the polar organic solvent forms hydrogen bonds with the polar lipid in the complex {Medina, 1998 #3}{Halim, 2012 #7}. In contrast, the polar organic solvent disrupts the hydrogen bond linking the polar lipid and membrane protein and dissociates the lipid complex away from the microalgal cell membrane {Halim, 2012 #7}. As a result, solvent-lipid complex is formed and diffuses out of the cell by concentration gradient {Halim, 2012

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