Table 4 Extraction methods of seaweed processing and their advantages and disadvantages
From: Global seaweed farming and processing in the past 20 years
Classification | Advantage | Shortage | Species | Reference |
|---|---|---|---|---|
Extraction in Soxhlet apparatus | Simple operation, relatively safe; reliable, effective and efficient; Suitable for lipid extraction | Small scope of application; Alcohol—water mixtures or non-polar solvents are involved | Chlorella sp. | |
Hydrothermal liquefaction | Different strains with high water content were transformed into high bio-oil yield; low coke and low energy consumption | Solvent influence, applicable scope is small | Microalgae | Vua et al. 2021; Chiaramonti et al. 2017 |
Simultaneous distillation extraction | Extraction of trace components, non pre-drying of biomass, cost saving | Large sample size, complex operation, easy to produce by-products | Nannochloropsis oculata (N. oculata); Dunaliella salina (D. salina) | Tanzi et al. 2013 |
Vacuum hydrodistillation for extraction | Non high temperature, conducive to low boiling point and high boiling point compounds extraction | Some volatile compounds may be lost or changed during concentration | LePape et al. 2002 | |
Liquid–liquid extraction | Continuous extraction; Minimizes the viability of microalgae | Extraction solvent is large; most of the solvent is toxic; more difficult to deal with | Microalgae; Dunaliella salina | Marchal et al. 2013 |
Dynamic headspace extraction | Flexible; Widely used; No need to heat the initial product | Complex: Concentration is difficult to achieve; Extract only low-boiling compounds | Palmariapalmata;Spirulina platensis | |
Solid phase microextraction | Simple and fast operation; Low sample demand; Solvent-free sampling technique; Widely used; It can be used to analyze volatile compounds | Insensitive to low volatile substances | Green, brown, and red algae | Alonso et al. 2003 |
Pulsed electric field | Irreversible electroporation inactivates microorganisms; Helps release substances from plant cells; Fast green | Size limit | Microalgae | Joannes et al. 2015 |
Microwave-assisted extraction | Short extraction time; less solvent; high extraction rate and low cost | Sensitive to heat and pressure; Energy is needed to provide radiant power; Additional separation processes are required to remove solids or unwanted materials from the solvent | Brown seaweeds | |
Ultrasound-assisted extraction | Easier to operate; Faster; Mass production; Good solubilizing effect; Energy saving and environmental protection | Used for heat resistant compounds; Extraction time; Microwave power; Influence of solid liquid ratio | Brown alga Sargassum | |
Supercritical fluid extraction | Environmental protection, cheap, widely available, non-flammable, time-saving | High cost; The machine is difficult to clean; The extraction range of compounds is small; Polar compounds are not applicable | Brown algae Fucus vesiculosus; Nannochloropsis sp.; marine algae Fucus vesicu-losus; Laminaria | Kumar et al. 2020; Dmytryk et al. 2015; Güçlü-Üstündağ et al. 2005 |
Pressurized solvent extraction | Common use; Fewer solvents yield more in a shorter time; Maintain the integrity of chemical composition | Sensitive to high temperature and pressure; Produces non-selective compound extraction; High initial cost | Haematococcus pluvialis; Dunaliella salina | Hossain et al. 2011; Turner & Waldebäck 2013; Reighard & Olesik 1996; Denery et al. 2004 |
Enzyme-assisted extraction | Biocompatibility, non-toxic; environmental protection; high catalytic efficiency; Retain the properties of the compound | Long time, high temperature, low extraction efficiency | Nordic seaweeds; Scenedesmus sp.; brown macroalgae |