Table 2 Overview of important extraction methods and their efficiency for lipid recovery
Method | Efficiency | Cost | Energy demands | Industrial perspective | References |
|---|---|---|---|---|---|
Conventional solvents such as chloroform/methanol, hexane, or ether | Depends on the species of microorganism, pretreatment of biomass, moisture content, type of solvent, solvent: biomass ratio, treatment time, etc. | Mainly the cost of solvents and reactors, possible reuse of solvents, energy-intensive process | Drying of cellular biomass, heating of solvent, distillation of solvent | There are reports at a larger scale | [46] |
Super critical CO2 | Varies with flow rate of CO2, pressure, and exposure time | Mainly the cost of equipment and its maintenance | Distillation/heating of solvents if paired with co-solvent, maintaining high-pressure conditions | No report at an industrial scale | |
Liquid CO2 | Requires cell disruption to achieve better yield, usually lipid yield is low | Maintenance of high-pressure conditions (15 MPa), cell disruption | Distillation/heating of solvents if paired with co-solvent | No reports at a larger scale | |
Microwave-assisted lipid extraction | Simple, rapid process, effective for robust species, easy to scale up; does not require dewatering of microorganisms; highly efficient at lab scale | Low operating costs but high maintenance costs of equipment | High energy consumption, recovery of thermolabile compounds may require cooling | No reports at a larger scale | |
Ultrasonication-assisted lipid extraction | Short extraction time, simple to operate, highly reproducible results, energy-effective in small volume, cell wall hinders lipid recovery | Mainly cost of equipment | Large volume of sample, requires high energy | Not suitable for large-scale |