Algae are a diverse group of photosynthetic organisms that play a vital role in the ecosystem. They are a rich source of bioactive compounds with potential applications in the food, pharmaceutical, and cosmetic industries. These bioactive compounds include proteins, lipids, carbohydrates, pigments, and antioxidants. The extraction and characterization of these compounds are essential for their potential utilization in various industries. Several conventional methods have been employed for the extraction of bioactive compounds from algae, such as solvent extraction, ultrasonic-assisted extraction, and enzyme-assisted extraction. However, these methods have limitations such as low selectivity, low extraction efficiency, and high energy consumption. Therefore, advanced methods like supercritical fluid extraction (SFE) have gained significant attention in recent years.
Supercritical fluid extraction is an advanced technique that involves the use of a supercritical fluid (SCF) as an extracting solvent. A supercritical fluid is a substance that exists above its critical temperature and pressure, exhibiting properties of both liquid and gas phases. Carbon dioxide (CO2) is the most commonly used SCF due to its low critical temperature (31.1°C) and pressure (73.8 bar), non-toxicity, non-flammability, and low cost.
The application of SFE for the extraction of bioactive compounds from algae offers several advantages over conventional methods. SFE provides higher selectivity and extraction efficiency due to the unique properties of SCFs. The solubility of the target compounds can be easily adjusted by changing the pressure and temperature during the extraction process. This allows for the selective extraction of specific compounds from complex matrices. Moreover, SFE is an eco-friendly process as it does not involve the use of toxic organic solvents.
Several studies have demonstrated the successful application of SFE for the extraction of bioactive compounds from different types of algae. For instance, researchers have reported the efficient extraction of carotenoids, such as astaxanthin and lutein, from microalgae using SFE. Astaxanthin is a potent antioxidant with potential applications in the food and cosmetic industries, while lutein is known for its protective effects against age-related macular degeneration.
Similarly, SFE has been employed for the extraction of lipids and fatty acids from macroalgae. These lipids can be further converted into biodiesel, making algae a promising renewable energy source. In addition to lipids and pigments, SFE has also been utilized for the extraction of phenolic compounds and polysaccharides from algae.
After the extraction process, various characterization techniques are employed to identify and quantify the extracted bioactive compounds. These techniques include chromatographic methods such as high-performance liquid chromatography (HPLC), gas chromatography (GC), and thin-layer chromatography (TLC), as well as spectroscopic methods like mass spectrometry (MS), nuclear magnetic resonance (NMR), and UV-Visible spectrophotometry.
Furthermore, advanced techniques like liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) are used for the identification of complex mixtures of bioactive compounds. These techniques provide detailed information about the molecular structure, molecular weight, and elemental composition of the compounds.
In conclusion, supercritical fluid extraction is an advanced method that offers several advantages over conventional extraction techniques for the extraction of bioactive compounds from algae. The application of SFE in combination with various characterization techniques has significantly contributed to the understanding of the chemical composition of algae and their potential applications in various industries. Further research is required to optimize the extraction conditions and explore the potential use of other supercritical fluids for the efficient extraction of bioactive compounds from algae.